Merge the latest trunk enhancements and fixes into the wal2 branch.

FossilOrigin-Name: d8cf1a62aff38de008f9b826c4846b15e37c89dc0f8bb412b79349da4d1580b0
Merge the latest trunk enhancements into the wal2 branch.
2026-05-29 18:08:48 +00:00 · 2026-04-22 19:47:59 +00:00 · 2026-04-08 19:28:10 +00:00 · 2026-04-02 11:52:54 +00:00 · 2026-03-27 12:38:30 +00:00 · 2026-03-21 17:56:26 +00:00
45 changed files with 3739 additions and 792 deletions
@@ -1578,6 +1578,7 @@ TESTEXT = \
  $(TOP)\ext\misc\amatch.c \
  $(TOP)\ext\misc\appendvfs.c \
  $(TOP)\ext\misc\basexx.c \
+  $(TOP)\ext\misc\bgckpt.c \
  $(TOP)\ext\misc\cksumvfs.c \
  $(TOP)\ext\misc\closure.c \
  $(TOP)\ext\misc\csv.c \
@@ -92,7 +92,6 @@ array set teaish__Config [proj-strip-hash-comments {
    -tm.tcl.in       TEAISH_TM_TCL_IN
    -options         {}
    -pragmas         {}
-    -src             {}
  }

  #
@@ -220,9 +219,7 @@ proc teaish-configure-core {} {
      => {Full pathname of tclsh to use.  It is used for trying to find
          tclConfig.sh.  Warning: if its containing dir has multiple tclsh
          versions, it may select the wrong tclConfig.sh!
-        Defaults to the $TCLSH environment variable.}
-
-    tcl-stubs=0 => {Enable use of Tcl stubs library.}
+          Defaults to the $TCLSH environment variable.}

    # TEA has --with-tclinclude but it appears to only be useful for
    # building an extension against an uninstalled copy of TCL's own
@@ -334,33 +331,29 @@ proc teaish-configure-core {} {
      -url              -       -v ""
      -tm.tcl           -       -v ""
      -tm.tcl.in        -       -v ""
-      -src              -       -v ""
    } {
-      #proj-assert 0 {Just testing}
      set isPIFlag [expr {"-" ne $pflag}]
      if {$isPIFlag} {
        if {[info exists ::teaish__PkgInfo($pflag)]} {
          # Was already set - skip it.
          continue;
        }
-        proj-assert {{-} eq $key};# "Unexpected pflag=$pflag key=$key type=$type val=$val"
+        proj-assert {{-} eq $key}
        set key $f2d($pflag)
      }
-      if {"" ne $key} {
-        if {"<nope>" ne [get-define $key "<nope>"]} {
-          # Was already set - skip it.
-          continue
-        }
+      proj-assert {"" ne $key}
+      set got [get-define $key "<nope>"]
+      if {"<nope>" ne $got} {
+        # Was already set - skip it.
+        continue
      }
      switch -exact -- $type {
        -v {}
        -e { set val [eval $val] }
        default { proj-error "Invalid type flag: $type" }
      }
-      #puts "***** defining default $pflag $key {$val} isPIFlag=$isPIFlag"
-      if {$key ne ""} {
-        define $key $val
-      }
+      #puts "***** defining default $pflag $key {$val} isPIFlag=$isPIFlag got=$got"
+      define $key $val
      if {$isPIFlag} {
        set ::teaish__PkgInfo($pflag) $val
      }
@@ -500,8 +493,6 @@ proc teaish__configure_phase1 {} {
  }
  teaish-checks-run -post

-  define TEAISH_USE_STUBS [opt-bool tcl-stubs]
-
  apply {{} {
    # Set up "vsatisfies" code for pkgIndex.tcl.in,
    # _teaish.tester.tcl.in, and for a configure-time check.  We would
@@ -531,7 +522,7 @@ proc teaish__configure_phase1 {} {
        set vputs "puts \[ $vsat \]"
        #puts "*** vputs = $vputs"
        scan [exec echo $vputs | $tclsh] %d vvcheck
-        if {![info exists vvcheck] || 0 == $vvcheck} {
+        if {0 == $vvcheck} {
          proj-fatal -up $tclsh "check failed:" $vsat
        }
      }
@@ -594,8 +585,7 @@ proc teaish__configure_phase1 {} {
  #
  if {0x0f & $::teaish__Config(pkginit-policy)} {
    file delete -force -- [get-define TEAISH_PKGINIT_TCL]
-    proj-dot-ins-append [get-define TEAISH_PKGINIT_TCL_IN] \
-      [get-define TEAISH_PKGINIT_TCL]
+    proj-dot-ins-append [get-define TEAISH_PKGINIT_TCL_IN]
  }
  if {0x0f & $::teaish__Config(tm-policy)} {
    file delete -force -- [get-define TEAISH_TM_TCL]
@@ -605,20 +595,17 @@ proc teaish__configure_phase1 {} {
  apply {{} {
    # Queue up any remaining dot-in files
    set dotIns [list]
-    foreach {dIn => dOut} {
-      TEAISH_TESTER_TCL_IN => TEAISH_TESTER_TCL
-      TEAISH_TEST_TCL_IN   => TEAISH_TEST_TCL
-      TEAISH_MAKEFILE_IN   => TEAISH_MAKEFILE
+    foreach d {
+      TEAISH_TESTER_TCL_IN
+      TEAISH_TEST_TCL_IN
+      TEAISH_MAKEFILE_IN
    } {
-      lappend dotIns [get-define $dIn ""] [get-define $dOut ""]
+      lappend dotIns [get-define $d ""]
    }
-    lappend dotIns $::autosetup(srcdir)/Makefile.in Makefile; # must be after TEAISH_MAKEFILE_IN.
-    # Much later: probably because of timestamps for deps purposes :-?
-    #puts "dotIns=$dotIns"
-    foreach {i o} $dotIns {
-      if {"" ne $i && "" ne $o} {
-        #puts " pre-dot-ins-append:  \[$i\] -> \[$o\]"
-        proj-dot-ins-append $i $o
+    lappend dotIns $::autosetup(srcdir)/Makefile.in; # must be after TEAISH_MAKEFILE_IN
+    foreach f $dotIns {
+      if {"" ne $f} {
+        proj-dot-ins-append $f
      }
    }
  }}
@@ -653,10 +640,10 @@ proc teaish__configure_phase1 {} {
  #
  # NO [define]s after this point!
  #
+  proj-dot-ins-process -validate
  proj-if-opt-truthy teaish-dump-defines {
    proj-file-write config.defines.txt $tdefs
  }
-  proj-dot-ins-process -validate

 }; # teaish__configure_phase1

@@ -830,9 +817,7 @@ proc teaish__check_tcl {} {
      if {"" ne $withSh &&
          [catch {exec echo "puts stdout \$auto_path" | "$withSh"} result] == 0} {
        foreach i $result {
-          if {![string match //zip* $i] && [file isdirectory $i]} {
-            # isdirectory actually passes on //zipfs:/..., but those are
-            # useless for our purposes
+          if {[file isdirectory $i]} {
            set tcllibdir $i/$extDirName
            break
          }
@@ -1081,7 +1066,7 @@ If you are attempting an out-of-tree build, use
         ]]} {
    if {[string match *.in $extM]} {
      define TEAISH_MAKEFILE_IN $extM
-      define TEAISH_MAKEFILE _[file rootname [file tail $extM]]
+      define TEAISH_MAKEFILE [file rootname [file tail $extM]]
    } else {
      define TEAISH_MAKEFILE_IN ""
      define TEAISH_MAKEFILE $extM
@@ -1149,8 +1134,8 @@ If you are attempting an out-of-tree build, use
  set flist [list $dirExt/teaish.test.tcl.in $dirExt/teaish.test.tcl]
  if {[proj-first-file-found ttt $flist]} {
    if {[string match *.in $ttt]} {
-      # Generate _teaish.test.tcl from $ttt
-      set xt _[file rootname [file tail $ttt]]
+      # Generate teaish.test.tcl from $ttt
+      set xt [file rootname [file tail $ttt]]
      file delete -force -- $xt; # ensure no stale copy is used
      define TEAISH_TEST_TCL $xt
      define TEAISH_TEST_TCL_IN $ttt
@@ -1317,6 +1302,7 @@ proc teaish-ldflags-prepend {args} {
 # object files (which are typically in the build tree)).
 #
 proc teaish-src-add {args} {
+  set i 0
  proj-parse-simple-flags args flags {
    -dist 0 {expr 1}
    -dir  0 {expr 1}
@@ -1401,7 +1387,7 @@ proc teaish__cleanup_rule {{tgt clean}} {
  return ${tgt}-_${x}_
 }

-# @teaish-make-obj ?flags? ?...args?
+# @teaish-make-obj objfile srcfile ?...args?
 #
 # Uses teaish-make-add to inject makefile rules for $objfile from
 # $srcfile, which is assumed to be C code which uses libtcl. Unless
@@ -1415,45 +1401,43 @@ proc teaish__cleanup_rule {{tgt clean}} {
 # Any arguments after the 2nd may be flags described below or, if no
 # -recipe is provided, flags for the compiler call.
 #
-#   -obj obj-filename.o
-#
-#   -src src-filename.c
-#
 #   -recipe {...}
 #   Uses the trimmed value of {...} as the recipe, prefixing it with
 #   a single hard-tab character.
 #
 #   -deps {...}
-#   List of extra files to list as dependencies of $o.
+#   List of extra files to list as dependencies of $o. Good luck
+#   escaping non-trivial cases properly.
 #
 #   -clean
 #   Generate cleanup rules as well.
-proc teaish-make-obj {args} {
-  proj-parse-simple-flags args flags {
-    -clean 0 {expr 1}
-    -recipe => {}
-    -deps => {}
-    -obj => {}
-    -src => {}
-  }
-  #parray flags
-  if {"" eq $flags(-obj)} {
-    set args [lassign $args flags(-obj)]
-    if {"" eq $flags(-obj)} {
-      proj-error "Missing -obj flag."
+proc teaish-make-obj {o src args} {
+  set consume 0
+  set clean 0
+  set flag ""
+  array set flags {}
+  set xargs {}
+  foreach arg $args {
+    if {$consume} {
+      set consume 0
+      set flags($flag) $arg
+      continue
+    }
+    switch -exact -- $arg {
+      -clean {incr clean}
+      -recipe -
+      -deps {
+        set flag $arg
+        incr consume
+      }
+      default {
+        lappend xargs $arg
+      }
    }
  }
-  foreach f {-deps -src} {
-    set flags($f) [string trim [string map {\n " "} $flags($f)]]
-  }
-  foreach f {-deps -src} {
-    set flags($f) [string trim $flags($f)]
-  }
-  #parray flags
-  #puts "-- args=$args"
  teaish-make-add \
-    "# [proj-scope 1] -> [proj-scope] $flags(-obj) $flags(-src)" -nl \
-    "$flags(-obj): $flags(-src) $::teaish__Config(teaish.tcl)"
+    "# [proj-scope 1] -> [proj-scope] $o $src" -nl \
+    "$o: $src $::teaish__Config(teaish.tcl)"
  if {[info exists flags(-deps)]} {
    teaish-make-add " " [join $flags(-deps)]
  }
@@ -1461,12 +1445,12 @@ proc teaish-make-obj {args} {
  if {[info exists flags(-recipe)]} {
    teaish-make-add [string trim $flags(-recipe)] -nl
  } else {
-    teaish-make-add [join [list \$(CC.tcl) -c $flags(-src) {*}$args]] -nl
+    teaish-make-add [join [list \$(CC.tcl) -c $src {*}$xargs]] -nl
  }
-  if {$flags(-clean)} {
+  if {$clean} {
    set rule [teaish__cleanup_rule]
    teaish-make-add \
-      "clean: $rule\n$rule:\n\trm -f \"$flags(-obj)\"\n"
+      "clean: $rule\n$rule:\n\trm -f \"$o\"\n"
  }
 }

@@ -2094,17 +2078,6 @@ proc teaish-pkginfo-set {args} {
        set v $x
      }

-      -src {
-        set d $::teaish__Config(extension-dir)
-        foreach f $v {
-          lappend ::teaish__Config(dist-files) $f
-          lappend ::teaish__Config(extension-src) $d/$f
-          lappend ::teaish__PkgInfo(-src) $f
-          # ^^^ so that default-value initialization in
-          # teaish-configure-core recognizes that it's been set.
-        }
-      }
-
      -tm.tcl -
      -tm.tcl.in {
        if {0x30 & $::teaish__Config(pkgindex-policy)} {
@@ -2542,7 +2515,7 @@ proc teaish__install {{dDest ""}} {
                             ] {
    teaish__verbose 1 msg-result "Copying files to $destDir..."
    file mkdir $destDir
-    foreach f  [glob -nocomplain -directory $srcDir *] {
+    foreach f  [glob -directory $srcDir *] {
      if {[string match {*~} $f] || [string match "#*#" [file tail $f]]} {
        # Editor-generated backups and emacs lock files
        continue
@@ -99,7 +99,7 @@ proc test__affert {failMode args} {
    lassign $args script msg
  }
  incr ::test__Counters($what)
-  if {![uplevel 1 expr [list $script]]} {
+  if {![uplevel 1 [concat expr [list $script]]]} {
    if {"" eq $msg} {
      set msg $script
    }
@@ -136,40 +136,6 @@ proc assert {args} {
  tailcall test__affert 1 {*}$args
 }

-#
-# @assert-matches ?-e? pattern ?-e? rhs ?msg?
-#
-# Equivalent to assert {[string match $pattern $rhs]} except that
-# if either of those are prefixed with an -e flag, they are eval'd
-# and their results are used.
-#
-proc assert-matches {args} {
-  set evalLhs 0
-  set evalRhs 0
-  if {"-e" eq [lindex $args 0]} {
-    incr evalLhs
-    set args [lassign $args -]
-  }
-  set args [lassign $args pattern]
-  if {"-e" eq [lindex $args 0]} {
-    incr evalRhs
-    set args [lassign $args -]
-  }
-  set args [lassign $args rhs msg]
-
-  if {$evalLhs} {
-    set pattern [uplevel 1 $pattern]
-  }
-  if {$evalRhs} {
-    set rhs [uplevel 1 $rhs]
-  }
-  #puts "***pattern=$pattern\n***rhs=$rhs"
-  tailcall test__affert 1 \
-    [join [list \[ string match [list $pattern] [list $rhs] \]]] $msg
-  # why does this not work? [list \[ string match [list $pattern] [list $rhs] \]] $msg
-  # "\[string match [list $pattern] [list $rhs]\]"
-}
-
 #
 # @test-assert testId script ?msg?
 #
@@ -191,7 +157,7 @@ proc test-expect {testId script result} {
  puts "test $testId"
  set x [string trim [uplevel 1 $script]]
  set result [string trim $result]
-  tailcall test__affert 0 [list "{$x}" eq "{$result}"] \
+  tailcall test__affert 0 [list $x eq $result] \
    "\nEXPECTED: <<$result>>\nGOT:      <<$x>>"
 }

@@ -203,7 +169,7 @@ proc test-expect {testId script result} {
 #
 proc test-catch {cmd args} {
  if {[catch {
-    uplevel 1 $cmd {*}$args
+    $cmd {*}$args
  } rc xopts]} {
    puts "[test-current-scope] ignoring failure of: $cmd [lindex $args 0]: $rc"
    return 1
@@ -211,37 +177,6 @@ proc test-catch {cmd args} {
  return 0
 }

-#
-# @test-catch-matching pattern (script|cmd args...)
-#
-# Works like test-catch, but it expects its argument(s) to to throw an
-# error matching the given string (checked with [string match]).  If
-# they do not throw, or the error does not match $pattern, this
-# function throws, else it returns 1.
-#
-# If there is no second argument, the $cmd is assumed to be a script,
-# and will be eval'd in the caller's scope.
-#
-# TODO: add -glob and -regex flags to control matching flavor.
-#
-proc test-catch-matching {pattern cmd args} {
-  if {[catch {
-    #puts "**** catch-matching cmd=$cmd args=$args"
-    if {0 == [llength $args]} {
-      uplevel 1 $cmd {*}$args
-    } else {
-      $cmd {*}$args
-    }
-  } rc xopts]} {
-    if {[string match $pattern $rc]} {
-      return 1
-    } else {
-      error "[test-current-scope] exception does not match {$pattern}: {$rc}"
-    }
-  }
-  error "[test-current-scope] expecting to see an error matching {$pattern}"
-}
-
 if {![array exists ::teaish__BuildFlags]} {
  array set ::teaish__BuildFlags {}
 }
@@ -0,0 +1,98 @@
+
+Wal2 Mode Notes
+===============
+
+## Activating/Deactivating Wal2 Mode
+
+"Wal2" mode is very similar to "wal" mode. To change a database to wal2 mode,
+use the command:
+
+>
+     PRAGMA journal_mode = wal2;
+
+It is not possible to change a database directly from "wal" mode to "wal2"
+mode. Instead, it must first be changed to rollback mode. So, to change a wal
+mode database to wal2 mode, the following two commands may be used:
+
+>
+     PRAGMA journal_mode = delete;
+     PRAGMA journal_mode = wal2;
+
+A database in wal2 mode may only be accessed by versions of SQLite compiled
+from this branch. Attempting to use any other version of SQLite results in an
+SQLITE&#95;NOTADB error. A wal2 mode database may be changed back to rollback mode
+(making it accessible by all versions of SQLite) using:
+
+>
+     PRAGMA journal_mode = delete;
+
+## The Advantage of Wal2 Mode
+
+In legacy wal mode, when a writer writes data to the database, it doesn't
+modify the database file directly. Instead, it appends new data to the
+"&lt;database>-wal" file. Readers read data from both the original database
+file and the "&lt;database>-wal" file. At some point, data is copied from the
+"&lt;database>-wal" file into the database file, after which the wal file can
+be deleted or overwritten. Copying data from the wal file into the database
+file is called a "checkpoint", and may be done explictly (either by "PRAGMA
+wal&#95;checkpoint" or sqlite3&#95;wal&#95;checkpoint&#95;v2()), or
+automatically (by configuring "PRAGMA wal&#95;autocheckpoint" - this is the
+default).
+
+Checkpointers do not block writers, and writers do not block checkpointers.
+However, if a writer writes to the database while a checkpoint is ongoing,
+then the new data is appended to the end of the wal file. This means that,
+even following the checkpoint, the wal file cannot be overwritten or deleted,
+and so all subsequent transactions must also be appended to the wal file. The
+work of the checkpointer is not wasted - SQLite remembers which parts of the
+wal file have already been copied into the db file so that the next checkpoint
+does not have to do so again - but it does mean that the wal file may grow
+indefinitely if the checkpointer never gets a chance to finish without a
+writer appending to the wal file. There are also circumstances in which
+long-running readers may prevent a checkpointer from checkpointing the entire
+wal file - also causing the wal file to grow indefinitely in a busy system.
+
+Wal2 mode does not have this problem. In wal2 mode, wal files do not grow
+indefinitely even if the checkpointer never has a chance to finish
+uninterrupted.
+
+In wal2 mode, the system uses two wal files instead of one. The files are named
+"&lt;database>-wal" and "&lt;database>-wal2", where "&lt;database>" is of
+course the name of the database file. When data is written to the database, the
+writer begins by appending the new data to the first wal file. Once the first
+wal file has grown large enough, writers switch to appending data to the second
+wal file. At this point the first wal file can be checkpointed (after which it
+can be overwritten). Then, once the second wal file has grown large enough and
+the first wal file has been checkpointed, writers switch back to the first wal
+file. And so on.
+
+## Application Programming
+
+From the point of view of the user, the main differences between wal and 
+wal2 mode are to do with checkpointing:
+
+  * In wal mode, a checkpoint may be attempted at any time. In wal2 
+    mode, the checkpointer has to wait until writers have switched 
+    to the "other" wal file before a checkpoint can take place.
+
+  * In wal mode, the wal-hook (callback registered using
+    sqlite3&#95;wal&#95;hook()) is invoked after a transaction is committed
+    with the total number of pages in the wal file as an argument. In wal2
+    mode, the argument is either the total number of uncheckpointed pages in
+    both wal files, or - if the "other" wal file is empty or already
+    checkpointed - 0.
+
+Clients are recommended to use the same strategies for checkpointing wal2 mode
+databases as for wal databases - by registering a wal-hook using
+sqlite3&#95;wal&#95;hook() and attempting a checkpoint when the parameter
+exceeds a certain threshold.
+
+However, it should be noted that although the wal-hook is invoked after each
+transaction is committed to disk and database locks released, it is still
+invoked from within the sqlite3&#95;step() call used to execute the "COMMIT"
+command. In BEGIN CONCURRENT systems, where the "COMMIT" is often protected by
+an application mutex, this may reduce concurrency. In such systems, instead of
+executing a checkpoint from within the wal-hook, a thread might defer this
+action until after the application mutex has been released.
+
+
@@ -0,0 +1,228 @@
+/*
+** 2017-10-11
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+******************************************************************************
+**
+*/
+
+#if !defined(SQLITE_TEST) || defined(SQLITE_OS_UNIX)
+
+#include "sqlite3.h"
+#include <string.h>
+#include <pthread.h>
+
+/*
+** API declarations.
+*/
+typedef struct Checkpointer Checkpointer;
+int sqlite3_bgckpt_create(const char *zFilename, Checkpointer **pp);
+int sqlite3_bgckpt_checkpoint(Checkpointer *p, int bBlock);
+void sqlite3_bgckpt_destroy(Checkpointer *p);
+
+
+struct Checkpointer {
+  sqlite3 *db;                    /* Database handle */
+
+  pthread_t thread;               /* Background thread */
+  pthread_mutex_t mutex;
+  pthread_cond_t cond;
+
+  int rc;                         /* Error from "PRAGMA wal_checkpoint" */
+  int bCkpt;                      /* True if checkpoint requested */
+  int bExit;                      /* True if exit requested */
+};
+
+static void *bgckptThreadMain(void *pCtx){
+  int rc = SQLITE_OK;
+  Checkpointer *p = (Checkpointer*)pCtx;
+
+  while( rc==SQLITE_OK ){
+    int bExit;
+
+    pthread_mutex_lock(&p->mutex);
+    if( p->bCkpt==0 && p->bExit==0 ){
+      pthread_cond_wait(&p->cond, &p->mutex);
+    }
+    p->bCkpt = 0;
+    bExit = p->bExit;
+    pthread_mutex_unlock(&p->mutex);
+
+    if( bExit ) break;
+    rc = sqlite3_exec(p->db, "PRAGMA wal_checkpoint", 0, 0, 0);
+    if( rc==SQLITE_BUSY ){
+      rc = SQLITE_OK;
+    }
+  }
+
+  pthread_mutex_lock(&p->mutex);
+  p->rc = rc;
+  pthread_mutex_unlock(&p->mutex);
+  return 0;
+}
+
+void sqlite3_bgckpt_destroy(Checkpointer *p){
+  if( p ){
+    void *ret = 0;
+
+    /* Signal the background thread to exit */
+    pthread_mutex_lock(&p->mutex);
+    p->bExit = 1;
+    pthread_cond_broadcast(&p->cond);
+    pthread_mutex_unlock(&p->mutex);
+
+    pthread_join(p->thread, &ret);
+    sqlite3_close(p->db);
+    sqlite3_free(p);
+  }
+}
+
+
+int sqlite3_bgckpt_create(const char *zFilename, Checkpointer **pp){
+  Checkpointer *pNew = 0;
+  int rc;
+
+  pNew = (Checkpointer*)sqlite3_malloc(sizeof(Checkpointer));
+  if( pNew==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    memset(pNew, 0, sizeof(Checkpointer));
+    rc = sqlite3_open(zFilename, &pNew->db);
+  }
+
+  if( rc==SQLITE_OK ){
+    pthread_mutex_init(&pNew->mutex, 0);
+    pthread_cond_init(&pNew->cond, 0);
+    pthread_create(&pNew->thread, 0, bgckptThreadMain, (void*)pNew);
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_bgckpt_destroy(pNew);
+    pNew = 0;
+  }
+  *pp = pNew;
+  return rc;
+}
+
+int sqlite3_bgckpt_checkpoint(Checkpointer *p, int bBlock){
+  int rc;
+  pthread_mutex_lock(&p->mutex);
+  rc = p->rc;
+  if( rc==SQLITE_OK ){
+    p->bCkpt = 1;
+    pthread_cond_broadcast(&p->cond);
+  }
+  pthread_mutex_unlock(&p->mutex);
+  return rc;
+}
+
+#ifdef SQLITE_TEST
+#include "tclsqlite.h"
+
+const char *sqlite3ErrName(int rc);
+
+static void SQLITE_TCLAPI bgckpt_del(void * clientData){
+  Checkpointer *pCkpt = (Checkpointer*)clientData;
+  sqlite3_bgckpt_destroy(pCkpt);
+}
+
+/*
+** Tclcmd: $ckpt SUBCMD ...
+*/
+static int SQLITE_TCLAPI bgckpt_obj_cmd(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  Checkpointer *pCkpt = (Checkpointer*)clientData;
+  const char *aCmd[] = { "checkpoint", "destroy", 0 };
+  int iCmd;
+
+  if( objc<2 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "SUBCMD ...");
+    return TCL_ERROR;
+  }
+
+  if( Tcl_GetIndexFromObj(interp, objv[1], aCmd, "sub-command", 0, &iCmd) ){
+    return TCL_ERROR;
+  }
+
+  switch( iCmd ){
+    case 0: {
+      int rc;
+      int bBlock = 0;
+
+      if( objc>3 ){
+        Tcl_WrongNumArgs(interp, 2, objv, "?BLOCKING?");
+        return TCL_ERROR;
+      }
+      if( objc==3 && Tcl_GetBooleanFromObj(interp, objv[2], &bBlock) ){
+        return TCL_ERROR;
+      }
+
+      rc = sqlite3_bgckpt_checkpoint(pCkpt, bBlock);
+      if( rc!=SQLITE_OK ){
+        Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+        return TCL_ERROR;
+      }
+      break;
+    }
+
+    case 1: {
+      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
+      break;
+    }
+  }
+
+  return TCL_OK;
+}
+
+/*
+** Tclcmd: bgckpt CMDNAME FILENAME
+*/
+static int SQLITE_TCLAPI bgckpt_cmd(
+  void * clientData,
+  Tcl_Interp *interp,
+  int objc,
+  Tcl_Obj *CONST objv[]
+){
+  const char *zCmd;
+  const char *zFilename;
+  int rc;
+  Checkpointer *pCkpt;
+
+  if( objc!=3 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "CMDNAME FILENAME");
+    return TCL_ERROR;
+  }
+  zCmd = Tcl_GetString(objv[1]);
+  zFilename = Tcl_GetString(objv[2]);
+
+  rc = sqlite3_bgckpt_create(zFilename, &pCkpt);
+  if( rc!=SQLITE_OK ){
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
+    return TCL_ERROR;
+  }
+
+  Tcl_CreateObjCommand(interp, zCmd, bgckpt_obj_cmd, (void*)pCkpt, bgckpt_del);
+  Tcl_SetObjResult(interp, objv[1]);
+  return TCL_OK;
+}
+
+int Bgckpt_Init(Tcl_Interp *interp){
+  Tcl_CreateObjCommand(interp, "bgckpt", bgckpt_cmd, 0, 0);
+  return TCL_OK;
+}
+#endif   /* SQLITE_TEST */
+
+#else
+# include "tclsqlite.h"
+int Bgckpt_Init(Tcl_Interp *interp){ return TCL_OK; }
+#endif
@@ -49,36 +49,6 @@
  versions (approximately) 104-107 are extinct) we should change our
  usage of those methods to remove the "await".
 */
-//#if 0
-/**
-   2026-04-04: this file gets included by both the "opfs" and "opfs-wl"
-   VFSes. It would, in hindsight, hypothetically be possible to restructure
-   it very slightly to support both VFSes via a single Worker instance.
-
-   Some of the changes we would need for that:
-
-   - The xLock/xUnlock "op codes" would need to differ for each impl.
-   i.e. we'd need state.opIds.xLock{,WL} and state.opIds.xUnlock{,WL}
-   to distinguish between the two, rather than doing so when this Worker
-   is loaded.
-
-   - We would need to centralize loading of this Worker, outside of
-   the VFS-specific pieces, and change the handshake in order to be
-   able to distinguish between clients which support
-   Atomics.waitAsync() and those which do not ("opfs-wl" requires
-   waitAsync()).
-
-   One down-side would be for clients which, for whatever reason, want
-   to use both "opfs" and "opfs-wl" within the same session: because
-   both would go through the same Worker, any operations for one VFS
-   would, while they're being processed on this side of the proxy,
-   effectively block the other VFS from doing anything, potentially
-   deadlocking. This use case seems unlikely enough that it can
-   possibly be ruled out (or even reasonably flat-out prohibited by
-   the library).
-*/
-//#/if
-
 "use strict";
 const urlParams = new URL(globalThis.location.href).searchParams;
 const vfsName = urlParams.get('vfs');
@@ -708,9 +678,9 @@ const installAsyncProxy = function(){
      const lockName = "sqlite3-vfs-opfs:" + fh.filenameAbs;
      const oldLockType = fh.xLock;
      return new Promise((resolveWaitLoop) => {
-        //log("xLock() initial promise entered...");
+        //error("xLock() initial promise entered...");
        navigator.locks.request(lockName, { mode: requestedMode }, async (lock) => {
-          //log("xLock() Web Lock entered.", fh);
+          //error("xLock() Web Lock entered.", fh);
          __implicitLocks.delete(fid);
          let rc = 0;
          try{
@@ -756,7 +726,7 @@ const installAsyncProxy = function(){
        storeAndNotify('xUnlock', rc);
        return rc;
      }
-      //log("xUnlock()",fid, lockType, fh);
+      //error("xUnlock()",fid, lockType, fh);
      let rc = 0;
      if( lockType === state.sq3Codes.SQLITE_LOCK_NONE ){
        /* SQLite usually unlocks all the way to NONE */
@@ -766,7 +736,7 @@ const installAsyncProxy = function(){
        fh.xLock = lockType;
      }else if( lockType === state.sq3Codes.SQLITE_LOCK_SHARED
                && existing.mode === 'exclusive' ){
-        /* downgrade EXCLUSIVE -> SHARED */
+        /* downgrade Exclusive -> Shared */
        rc = await wlCloseHandle(fh);
        if( 0===rc ){
          fh.xLock = lockType;
@@ -912,6 +882,16 @@ const installAsyncProxy = function(){
                  operation */
        ) || [];
        //error("waitLoop() whichOp =",opId, f.opHandlers[opId].key, args);
+//#if 0
+        if( isWebLocker && (opId==opIds.xLock || opIds==opIds.xUnlock) ){
+          /* An expert suggests that this introduces a race condition,
+             but my eyes aren't seeing it. The hope was that this
+             would improve the lock speed a tick, but it does not
+             appear to. */
+          hnd(...args);
+          continue;
+        }
+//#/if
        await hnd(...args);
      }catch(e){
        error('in waitLoop():', e);
@@ -1,4 +1,4 @@
-//#if not omit-oo1
+//#ifnot omit-oo1
 /*
  2022-08-24

@@ -19,12 +19,10 @@
  slightly simpler client-side interface than the slightly-lower-level
  Worker API does.

-  In non-ESM builds this file necessarily exposes one global symbol,
-  but clients may freely `delete` that symbol after calling it.
+  This script necessarily exposes one global symbol, but clients may
+  freely `delete` that symbol after calling it.
 */
-//#if not defined target:es6-module
 'use strict';
-//#/if
 /**
   Configures an sqlite3 Worker API #1 Worker such that it can be
   manipulated via a Promise-based interface and returns a factory
@@ -111,12 +109,10 @@
   the callback is called one time for each row of the result set,
   passed the same worker message format as the worker API emits:

-   {
-      type:typeString,
+     {type:typeString,
      row:VALUE,
      rowNumber:1-based-#,
-      columnNames: array
-   }
+      columnNames: array}

   Where `typeString` is an internally-synthesized message type string
   used temporarily for worker message dispatching. It can be ignored
@@ -127,16 +123,19 @@
   callback.

   At the end of the result set, the same event is fired with
-   (row=undefined, rowNumber=null) to indicate that the end of the
-   result set has been reached. The rows arrive via worker-posted
-   messages, with all the implications of that.
+   (row=undefined, rowNumber=null) to indicate that
+   the end of the result set has been reached. Note that the rows
+   arrive via worker-posted messages, with all the implications
+   of that.

   Notable shortcomings:

-   - "v1" of this this API is not suitable for use as an ESM module
-     because ESM worker modules were not widely supported when it was
-     developed. For use as an ESM module, see the "v2" interface later
-     on in this file.
+   - This API was not designed with ES6 modules in mind. Neither Firefox
+     nor Safari support, as of March 2023, the {type:"module"} flag to the
+     Worker constructor, so that particular usage is not something we're going
+     to target for the time being:
+
+     https://developer.mozilla.org/en-US/docs/Web/API/Worker/Worker
 */
 globalThis.sqlite3Worker1Promiser = function callee(config = callee.defaultConfig){
  // Inspired by: https://stackoverflow.com/a/52439530
@@ -255,14 +254,10 @@ globalThis.sqlite3Worker1Promiser = function callee(config = callee.defaultConfi

 globalThis.sqlite3Worker1Promiser.defaultConfig = {
  worker: function(){
-//#if target:es6-bundler-friendly
+//#if target=es6-module
    return new Worker(new URL("sqlite3-worker1-bundler-friendly.mjs", import.meta.url),{
      type: 'module'
    });
-//#elif target:es6-module
-    return new Worker(new URL("sqlite3-worker1.mjs", import.meta.url),{
-      type: 'module'
-    });
 //#else
    let theJs = "sqlite3-worker1.js";
    if(this.currentScript){
@@ -278,15 +273,15 @@ globalThis.sqlite3Worker1Promiser.defaultConfig = {
      }
    }
    return new Worker(theJs + globalThis.location.search);
-//#/if
+//#endif
  }
-//#if not target:es6-module
+//#ifnot target=es6-module
  .bind({
    currentScript: globalThis?.document?.currentScript
  })
-//#/if
+//#endif
  ,
-  onerror: (...args)=>console.error('sqlite3Worker1Promiser():',...args)
+  onerror: (...args)=>console.error('worker1 promiser error',...args)
 }/*defaultConfig*/;

 /**
@@ -301,7 +296,7 @@ globalThis.sqlite3Worker1Promiser.defaultConfig = {
   after calling the original function and will reject if that
   function throws.
 */
-globalThis.sqlite3Worker1Promiser.v2 = function callee(config = callee.defaultConfig){
+sqlite3Worker1Promiser.v2 = function(config){
  let oldFunc;
  if( 'function' == typeof config ){
    oldFunc = config;
@@ -331,25 +326,21 @@ globalThis.sqlite3Worker1Promiser.v2 = function callee(config = callee.defaultCo
  }
  return p;
 }.bind({
-   /* We do this because clients are recommended to delete
-      globalThis.sqlite3Worker1Promiser. */
+   /* We do this because clients are
+      recommended to delete globalThis.sqlite3Worker1Promiser. */
  original: sqlite3Worker1Promiser
 });

-globalThis.sqlite3Worker1Promiser.v2.defaultConfig =
-  globalThis.sqlite3Worker1Promiser.defaultConfig;
-
-//#if target:es6-module
+//#if target=es6-module
 /**
  When built as a module, we export sqlite3Worker1Promiser.v2()
  instead of sqlite3Worker1Promise() because (A) its interface is more
-  conventional for ESM usage and (B) the ESM export option for this
-  API did not exist until v2 was created, so there's no backwards
+  conventional for ESM usage and (B) the ESM option export option for
+  this API did not exist until v2 was created, so there's no backwards
  incompatibility.
 */
 export default sqlite3Worker1Promiser.v2;
-delete globalThis.sqlite3Worker1Promiser;
-//#/if /* target:es6-module */
+//#endif /* target=es6-module */
 //#else
 /* Built with the omit-oo1 flag. */
-//#/if if not omit-oo1
+//#endif ifnot omit-oo1
@@ -6,11 +6,11 @@
    <link rel="shortcut icon" href="data:image/x-icon;," type="image/x-icon">
    <link rel="stylesheet" href="common/emscripten.css"/>
    <link rel="stylesheet" href="common/testing.css"/>
-//#if target:es6-module
-    <title>Worker1-promiser (ESM) tests</title>
+//#if target=es6-module
+    <title>worker-promise (via ESM) tests</title>
 //#else
-    <title>Worker1-promiser tests</title>
-//#/if
+    <title>worker-promise tests</title>
+//#endif
  </head>
  <body>
    <header id='titlebar'><span>worker-promise tests</span></header>
@@ -32,11 +32,11 @@
    <hr>
    <div id='test-output'></div>
    <script src="common/SqliteTestUtil.js"></script>
-//#if target:es6-module
+//#if target=es6-module
    <script src="demo-worker1-promiser.mjs" type="module"></script>
 //#else
    <script src="jswasm/sqlite3-worker1-promiser.js"></script>
    <script src="demo-worker1-promiser.js"></script>
-//#/if
+//#endif
  </body>
 </html>
@@ -13,13 +13,13 @@
  Demonstration of the sqlite3 Worker API #1 Promiser: a Promise-based
  proxy for for the sqlite3 Worker #1 API.
 */
-//#if target:es6-module
+//#if target=es6-module
 import {default as promiserFactory} from "./jswasm/sqlite3-worker1-promiser.mjs";
 //#else
 "use strict";
 const promiserFactory = globalThis.sqlite3Worker1Promiser.v2;
 delete globalThis.sqlite3Worker1Promiser;
-//#/if
+//#endif
 (async function(){
  const T = globalThis.SqliteTestUtil;
  const eOutput = document.querySelector('#test-output');
@@ -40,7 +40,7 @@ delete globalThis.sqlite3Worker1Promiser;
  };

  const promiserConfig = {
-//#if not target:es6-module
+//#ifnot target=es6-module
    /**
       The v1 interfaces uses an onready function. The v2 interface optionally
       accepts one but does not require it. If provided, it is called _before_
@@ -53,7 +53,7 @@ delete globalThis.sqlite3Worker1Promiser;
         before workerPromise is set. */
      console.warn("This is the v2 interface - you don't need an onready() function.");
    },
-//#/if
+//#endif
    debug: 1 ? undefined : (...args)=>console.debug('worker debug',...args),
    onunhandled: function(ev){
      error("Unhandled worker message:",ev.data);
@@ -115,7 +115,6 @@ delete globalThis.sqlite3Worker1Promiser;
            "insert into t(a,b) values(1,2),(3,4),(5,6)"
           ].join(';'),
      resultRows: [], columnNames: [],
-      lastInsertRowId: true,
      countChanges: sqConfig.bigIntEnabled ? 64 : true
    }, function(ev){
      ev = ev.result;
@@ -123,9 +122,7 @@ delete globalThis.sqlite3Worker1Promiser;
        .assert(0===ev.columnNames.length)
        .assert(sqConfig.bigIntEnabled
                ? (3n===ev.changeCount)
-                : (3===ev.changeCount))
-        .assert('bigint'===typeof ev.lastInsertRowId)
-        .assert(ev.lastInsertRowId>=3);
+                : (3===ev.changeCount));
    });

    await wtest('exec',{
@@ -27,7 +27,7 @@
    -->
    <script src="jqterm/jquery.terminal.bundle.min.js"></script>
    <link rel="stylesheet" href="jqterm/jquery.terminal.min.css">
-//#/if
+//#endif
    <style>
      /* The following styles are for app-level use. */
      :root {
@@ -322,9 +322,8 @@
  <h1>Usage Summary</h1>

  <ul>
-    <li class='hidden unhide-if-terminal-available'>In
-      <a href="https://github.com/jcubic/jquery.terminal">"terminal
-      mode"</a> it accepts input just like the CLI shell does.</li>
+    <li class='hidden unhide-if-terminal-available'>In "terminal
+      mode" it accepts input just like the CLI shell does.</li>
    <li>In split-view mode:
      <ul>
        <li>Input can be executed with either the Run
@@ -780,6 +780,7 @@ TESTSRC += \
  $(TOP)/ext/misc/amatch.c \
  $(TOP)/ext/misc/appendvfs.c \
  $(TOP)/ext/misc/basexx.c \
+  $(TOP)/ext/misc/bgckpt.c \
  $(TOP)/ext/misc/cksumvfs.c \
  $(TOP)/ext/misc/closure.c \
  $(TOP)/ext/misc/csv.c \
@@ -1,5 +1,5 @@
-C Rename\sthe\sext/misc/analyze.c\sextension\sto\sext/misc/diskused.c,\sto\savoid\nconfusion\swith\sthe\ssrc/analyze.c\sfile.\s\sThe\sfunction\sis\snow\scalled\n"diskused(X)"\sinstead\sof\s"analyze(X)".\s\sThe\sCLI\scommand\sis\srenamed\nfrom\s".dbstat"\sto\s".diskused".
-D 2026-05-29T14:57:38.380
+C Merge\sthe\slatest\strunk\senhancements\sand\sfixes\sinto\sthe\swal2\sbranch.
+D 2026-05-29T18:08:48.599
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -7,7 +7,7 @@ F AGENTS.md 44ddfb38ef23e277888bd70ae378e6cbf5f5cab0e2a4420bd21d89b6caff7a4a
 F LICENSE.md 6bc480fc673fb4acbc4094e77edb326267dd460162d7723c7f30bee2d3d9e97d
 F Makefile.in 5fda086f33b144da08119255da1d2557f983d0764a13707f05acf0159fd89ba5
 F Makefile.linux-generic bd3e3cacd369821a6241d4ea1967395c962dfe3057e38cb0a435cee0e8b789d0
-F Makefile.msc 3b2129c90e15ea734682c8769b567012200ac30d7ff1e73c4717e23edbe1bb4b
+F Makefile.msc 1b910fff2865b4517db9e525ce33bf62988cc8f72feaf6f8fafbe6e41f7f881e
 F README.md f00091ffb5c6379b783afb57ca5f443a5742e119082f37c407f64a5e16c56346
 F VERSION 99cf3be5f13d091183e4314b7fc2e0c0e69accfbe64608b45a313338bbdd7b62
 F art/icon-243x273.gif 9750b734f82fdb3dc43127753d5e6fbf3b62c9f4e136c2fbf573b2f57ea87af5
@@ -51,9 +51,9 @@ F autosetup/proj.tcl 67683f214977a416baafc4c1020f9940ff047a7306b2292c5872d628746
 F autosetup/sqlite-config.tcl 2205b8bcc193a5d46584ebc1cf44c7a93a977d155e20dc38b18dcce720e58074
 F autosetup/system.tcl 51d4be76cd9a9074704b584e5c9cbba616202c8468cf9ba8a4f8294a7ab1dba9
 F autosetup/teaish/README.txt b40071e6f8506500a2f7f71d5fc69e0bf87b9d7678dd9da1e5b4d0acbf40b1ca
-F autosetup/teaish/core.tcl e014dd95900c7f9a34e8e0f460f47e94841059827bce8b4c49668b0c7ae3f1a0
+F autosetup/teaish/core.tcl 1ebbe849d8e716424a3ffe9384c7e8b352b3e1194d3d4a153b125cc5176b3715
 F autosetup/teaish/feature.tcl 18194fb79a24d30e5bbdeab40999616f39278b53a27525349ded033af2fd73be
-F autosetup/teaish/tester.tcl 1799514c2652db49561b3386c5242b94534d1663f2cfac861a955e071895fdd0
+F autosetup/teaish/tester.tcl 091745984473faea6985254b9986c6dfd0cce06f68bc515ba4afc1e6b3742fa8
 F configure 9a00b21dfd13757bbfb8d89b30660a89ec1f8f3a79402b8f9f9b6fc475c3303a x
 F contrib/sqlitecon.tcl eb4c6578e08dd353263958da0dc620f8400b869a50d06e271ab0be85a51a08d3
 F doc/F2FS.txt c1d4a0ae9711cfe0e1d8b019d154f1c29e0d3abfe820787ba1e9ed7691160fcd
@@ -69,6 +69,7 @@ F doc/trusted-schema.md 33625008620e879c7bcfbbfa079587612c434fa094d338b08242288d
 F doc/vdbesort-memory.md 4da2639c14cd24a31e0af694b1a8dd37eaf277aff3867e9a8cc14046bc49df56
 F doc/vfs-shm.txt 1a55f3f0e7b6745931b117ba5c9df3640d7a0536f532ef0052563100f4416f86
 F doc/wal-lock.md 7db0cd61e2000b545b78ce89b0c2a9a8dd8d64c097839258ac10d7c5c4156ec1
+F doc/wal2.md a807405a05e19a4945c5905a9ffa0fe45b8560dd7572461192501f565c19cdb5
 F ext/README.md 6eb1ac267d917767952ed0ef63f55de003b6a5da433ce1fa389e1a9532e73132
 F ext/expert/README.md b321c2762bb93c18ea102d5a5f7753a4b8bac646cb392b3b437f633caf2020c3
 F ext/expert/expert.c d548d603a4cc9e61f446cc179c120c6713511c413f82a4a32b1e1e69d3f086a4
@@ -365,6 +366,7 @@ F ext/misc/appendvfs.c 9642c7a194a2a25dca7ad3e36af24a0a46d7702168c4ad7e59c9f9b0e
 F ext/misc/base64.c 1445761667c16356e827fc6418294c869468be934429aaa8315035e76dd58acf
 F ext/misc/base85.c c713c7c81b05558c488cbdd8c68d612d5a97f9f0b8adf1167148dd7c89ce3f96
 F ext/misc/basexx.c 89ad6b76558efbceb627afd5e2ef1d84b2e96d9aaf9b7ecb20e3d00b51be6fcf
+F ext/misc/bgckpt.c 18cfc9c39ffab3299f730f86ae2991c8574c0bd9ec80efd2f89196798a7b7181
 F ext/misc/blobio.c a867c4c4617f6ec223a307ebfe0eabb45e0992f74dd47722b96f3e631c0edb2a
 F ext/misc/btreeinfo.c 5fe97f798a9ee90e92b3031ed7969ec3f558661bb36b821c3ba045a17cfb951c
 F ext/misc/cksumvfs.c 9d7d0cf1a8893ac5d48922bfe9f3f217b4a61a6265f559263a02bb2001259913
@@ -600,7 +602,7 @@ F ext/wasm/api/sqlite3-api-oo1.c-pp.js 35e4727010f15fd72ead0dd1eb4e3c2c9bb1cc60e
 F ext/wasm/api/sqlite3-api-prologue.js 0084e15d66fbcd75cacbaa58e3b473d5e57082c30f3122be7fdadff5589cf6b6
 F ext/wasm/api/sqlite3-api-worker1.c-pp.js 1fa34e9b0e3b90a8898e4f700d7125e44c81877f182627bb8564b97989bc6e78
 F ext/wasm/api/sqlite3-license-version-header.js 98d90255a12d02214db634e041c8e7f2f133d9361a8ebf000ba9c9af4c6761cc
-F ext/wasm/api/sqlite3-opfs-async-proxy.c-pp.js 25e31482b04293a33d7599f1459eb552b3eb36ca10c02c816122d3308bf80cb2
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 F test/wal2.test f058016abe4627d2664db4b4b87990298d925e66a4c5a2c8e674a0ff6f4c841d
+F test/wal2big.test 829141cbecdda4329db8fa38705424c4a73db72a06b9540b06811a825d330409
+F test/wal2fault.test 2e8e60cacd5bcd451618aeffd05f676894d17202d3e2986e288d36e2c5993249
+F test/wal2lock.test 0ef98d72dc6bcf7711dedd684760488400d9a9a6eec0dc5d3822060437793552
+F test/wal2openclose.test 2b26be723ea7f4263c8d5d70b37efd1c359561a0526e39466c45fe8e6478daee
+F test/wal2recover.test 348a3f2a4c79359790f70fd692dcd0c8f04e42a85365e688778c945e10bae02b
+F test/wal2recover2.test 3fe5d5932b16a3a38304a85bafed1f965faef40c230fd450838a0502e61343bb
+F test/wal2recover3.test 4a91689e165a38bc401736e6518188c2b0ff4fa1566d1810b8867536db128177
+F test/wal2rewrite.test 6ca6f631ffcf871240beab5f02608913fd075c6d0d31310b026c8383c65c9f9c
+F test/wal2rollback.test 23adc4a099b23f6aaea8b04fdca1c35861d887dd80f8be7da2d5273eb777e428
+F test/wal2savepoint.test c380512ec1f97012cfc753e718bf3df38f51e7c319110e1cae25094a33b371c4
+F test/wal2simple.test d2d94fe1f30700c9f30e46c16f1c3d7d245b861a1be2bfe5ead701484c6dd38e
+F test/wal2snapshot.test 7a5f4629a3c43a43c3440b8b2ea9f07de91a46b0b9eea5f08f62b5bf5b6468df
 F test/wal3.test 5de023bb862fd1eb9d2ad26fa8d9c43abb5370582e5b08b2ae0d6f93661bc310
 F test/wal4.test 4744e155cd6299c6bd99d3eab1c82f77db9cdb3c
 F test/wal5.test 9c11da7aeccd83a46d79a556ad11a18d3cb15aa9
@@ -2020,7 +2034,7 @@ F test/walnoshm.test 844b3eb7d8e8ee76c834ef723babec57b0be51fa52ef7e321c289ed0fe3
 F test/waloverwrite.test dad2f26567f1b45174e54fbf9a8dc1cb876a7f03
 F test/walpersist.test 8d78a1ec91299163451417b451a2bac3481f8eb9f455b1ca507a6625c927ca6e
 F test/walprotocol.test 1b3f922125e341703f6e946d77fdc564d38fb3e07a9385cfdc6c99cac1ecf878
-F test/walprotocol2.test 7d3b6b4bf0b12f8007121b1e6ef714bc99101fb3b48e46371df1db868eebc131
+F test/walprotocol2.test 7e4bedd5ee83607e2928ac438bf7332a396b980d3e02aa0746509ce11ad1f13c
 F test/walrestart.test 5168c0c2414d1971d8dec949c1070a0144cf15402361ba0d0e6a8054f5598a64
 F test/walro.test 78a84bc0fdae1385c06b017215c426b6845734d6a5a3ac75c918dd9b801b1b9d
 F test/walro2.test 33955a6fd874dd9724005e17f77fef89d334b3171454a1256fe4941a96766cdc
@@ -2149,7 +2163,7 @@ F tool/mkamalzip.tcl 8aa5ebe7973c8b8774062d34e15fea9815c4cc2ceea3a9b184695f00591
 F tool/mkautoconfamal.sh 06fbe090b81c24e592c1f22b404334f805ba74d482a9260f2ac81e6f3d3386d8
 F tool/mkccode.tcl c42a8f8cf78f92e83795d5447460dbce7aaf78a3bbf9082f1507dc71a3665f3c x
 F tool/mkcombo.tcl 2a5189b219c4a495e1ff7fc980bd568d3cfb82ae9d50c84e77f7a161e96fc132
-F tool/mkctimec.tcl 68f3ee9e2e6a06524b25d79b5b61a883053466080a39da59e0a0697f0c4d9a3b x
+F tool/mkctimec.tcl bbaa2265949d8825c68ceacd76d5c230b247493547ce9e6c08335e73055cdf4d x
 F tool/mkfptab.c 24ea40113f96584caca3f6dd06b4ad5adffa0f39023910cb83fa7ef2ffa9b0ba
 F tool/mkkeywordhash.c 82d5af1d0e677900739fba59155cddac172d8c712c2d91ab73d6e6bcb30060f0
 F tool/mkmsvcmin.tcl d76c45efda1cce2d4005bcea7b8a22bb752e3256009f331120fb4fecb14ebb7a
@@ -2203,13 +2217,13 @@ F tool/tclConfigShToMake.sh 7c065d81c2d178e15e45a77372c6e5a38b5a1b08755301cd6f20
 F tool/varint.c 5d94cb5003db9dbbcbcc5df08d66f16071aee003
 F tool/vdbe-compress.tcl fa2f37ab39b2a0087fafb6a7f3ce19503e25e624ffa8ed9951717ab72920c088
 F tool/vdbe_profile.tcl 3ac5a4a9449f4baf77059358ea050db3e34395ccf59c5464d29b91746d5b961e
-F tool/version-info.c 33d0390ef484b3b1cb685d59362be891ea162123cea181cb8e6d2cf6ddf2700c
+F tool/version-info.c 3b36468a90faf1bbd59c65fd0eb66522d9f941eedd364fabccd72273503ae7d5
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
 F tool/warnings.sh a554d13f6e5cf3760f041b87939e3d616ec6961859c3245e8ef701d1eafc2ca2
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
-P d15cd64160192119a5f12afec14dbfbb30fb38a8557cb9dc559b3f061c15687a
-R b94ebbf5e61926662e4d4c59c4ea9472
+P 28d1d29ad465b150ea705af8352c0e6599b3f42c15474b2ae89e8a2c2b9b097c c7839f7a1749b38f8a36c06d93a7b59095e91ce753e8dd020de273ca8f73a239
+R da9eb2c8c6fc545fa76a8916647efb64
 U drh
-Z c87a787fc483b6eb7052d881e8ec7a13
+Z 81655c913c3efc0b9200f9ede46569c5
 # Remove this line to create a well-formed Fossil manifest.
@@ -1,2 +1,2 @@
-branch trunk
-tag trunk
+branch wal2
+tag wal2
@@ -1 +1 @@
-c7839f7a1749b38f8a36c06d93a7b59095e91ce753e8dd020de273ca8f73a239
+d8cf1a62aff38de008f9b826c4846b15e37c89dc0f8bb412b79349da4d1580b0
@@ -3329,10 +3329,10 @@ static int lockBtree(BtShared *pBt){
      goto page1_init_failed;
    }
 #else
-    if( page1[18]>2 ){
+    if( page1[18]>3 ){
      pBt->btsFlags |= BTS_READ_ONLY;
    }
-    if( page1[19]>2 ){
+    if( page1[19]>3 ){
      goto page1_init_failed;
    }

@@ -3344,9 +3344,9 @@ static int lockBtree(BtShared *pBt){
    ** may not be the latest version - there may be a newer one in the log
    ** file.
    */
-    if( page1[19]==2 && (pBt->btsFlags & BTS_NO_WAL)==0 ){
+    if( page1[19]>=2 && (pBt->btsFlags & BTS_NO_WAL)==0 ){
      int isOpen = 0;
-      rc = sqlite3PagerOpenWal(pBt->pPager, &isOpen);
+      rc = sqlite3PagerOpenWal(pBt->pPager, (page1[19]==3), &isOpen);
      if( rc!=SQLITE_OK ){
        goto page1_init_failed;
      }else{
@@ -11510,7 +11510,7 @@ int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
  BtShared *pBt = pBtree->pBt;
  int rc;                         /* Return code */

-  assert( iVersion==1 || iVersion==2 );
+  assert( iVersion==1 || iVersion==2 || iVersion==3 );

  /* If setting the version fields to 1, do not automatically open the
  ** WAL connection, even if the version fields are currently set to 2.
@@ -932,6 +932,7 @@ static int assert_pager_state(Pager *p){
        assert( isOpen(p->jfd)
             || p->journalMode==PAGER_JOURNALMODE_OFF
             || p->journalMode==PAGER_JOURNALMODE_WAL
+             || p->journalMode==PAGER_JOURNALMODE_WAL2
        );
      }
      assert( pPager->dbOrigSize==pPager->dbFileSize );
@@ -946,6 +947,7 @@ static int assert_pager_state(Pager *p){
      assert( isOpen(p->jfd)
           || p->journalMode==PAGER_JOURNALMODE_OFF
           || p->journalMode==PAGER_JOURNALMODE_WAL
+           || p->journalMode==PAGER_JOURNALMODE_WAL2
           || (sqlite3OsDeviceCharacteristics(p->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
      );
      assert( pPager->dbOrigSize<=pPager->dbHintSize );
@@ -958,6 +960,7 @@ static int assert_pager_state(Pager *p){
      assert( isOpen(p->jfd)
           || p->journalMode==PAGER_JOURNALMODE_OFF
           || p->journalMode==PAGER_JOURNALMODE_WAL
+           || p->journalMode==PAGER_JOURNALMODE_WAL2
           || (sqlite3OsDeviceCharacteristics(p->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
      );
      break;
@@ -2103,6 +2106,7 @@ static int pager_end_transaction(Pager *pPager, int hasSuper, int bCommit){
      assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE
           || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
           || pPager->journalMode==PAGER_JOURNALMODE_WAL
+           || pPager->journalMode==PAGER_JOURNALMODE_WAL2
      );
      sqlite3OsClose(pPager->jfd);
      if( bDelete ){
@@ -3261,6 +3265,10 @@ static int pagerBeginReadTransaction(Pager *pPager){
  if( rc!=SQLITE_OK || changed ){
    pager_reset(pPager);
    if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
+    assert( pPager->journalMode==PAGER_JOURNALMODE_WAL
+         || pPager->journalMode==PAGER_JOURNALMODE_WAL2
+    );
+    pPager->journalMode = sqlite3WalJournalMode(pPager->pWal);
  }

  return rc;
@@ -3356,9 +3364,9 @@ static int pagerOpenWalIfPresent(Pager *pPager){
          rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
        }else{
          testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
-          rc = sqlite3PagerOpenWal(pPager, 0);
+          rc = sqlite3PagerOpenWal(pPager, 0, 0);
        }
-      }else if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
+      }else if( pPager->journalMode>=PAGER_JOURNALMODE_WAL ){
        pPager->journalMode = PAGER_JOURNALMODE_DELETE;
      }
    }
@@ -4879,6 +4887,7 @@ int sqlite3PagerOpen(
    (u64)nPathname + 8 + 1 +             /* Journal filename */
 #ifndef SQLITE_OMIT_WAL
    (u64)nPathname + 4 + 1 +             /* WAL filename */
+    nPathname + 5 + 1 +                  /* Second WAL filename */
 #endif
    3                                    /* Terminator */
  );
@@ -4931,6 +4940,8 @@ int sqlite3PagerOpen(
    sqlite3FileSuffix3(zFilename, pPager->zWal);
    pPtr = (u8*)(pPager->zWal + sqlite3Strlen30(pPager->zWal)+1);
 #endif
+    memcpy(pPtr, zPathname, nPathname);   pPtr += nPathname;
+    memcpy(pPtr, "-wal2", 5);             pPtr += 5 + 1;
  }else{
    pPager->zWal = 0;
  }
@@ -7367,7 +7378,8 @@ int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
            || eMode==PAGER_JOURNALMODE_OFF       /* 2 */
            || eMode==PAGER_JOURNALMODE_TRUNCATE  /* 3 */
            || eMode==PAGER_JOURNALMODE_MEMORY    /* 4 */
-            || eMode==PAGER_JOURNALMODE_WAL       /* 5 */ );
+            || eMode==PAGER_JOURNALMODE_WAL       /* 5 */
+            || eMode==PAGER_JOURNALMODE_WAL2      /* 6 */ );

  /* This routine is only called from the OP_JournalMode opcode, and
  ** the logic there will never allow a temporary file to be changed
@@ -7401,9 +7413,12 @@ int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
    assert( (PAGER_JOURNALMODE_MEMORY & 5)==4 );
    assert( (PAGER_JOURNALMODE_OFF & 5)==0 );
    assert( (PAGER_JOURNALMODE_WAL & 5)==5 );
+    assert( (PAGER_JOURNALMODE_WAL2 & 5)==4 );

    assert( isOpen(pPager->fd) || pPager->exclusiveMode );
-    if( !pPager->exclusiveMode && (eOld & 5)==1 && (eMode & 1)==0 ){
+    if( !pPager->exclusiveMode && (eOld & 5)==1 && (eMode & 1)==0 
+     && eMode!=PAGER_JOURNALMODE_WAL2       /* TODO: fix this if possible */
+    ){
      /* In this case we would like to delete the journal file. If it is
      ** not possible, then that is not a problem. Deleting the journal file
      ** here is an optimization only.
@@ -7578,7 +7593,7 @@ static int pagerExclusiveLock(Pager *pPager){
 ** lock on the database file and use heap-memory to store the wal-index
 ** in. Otherwise, use the normal shared-memory.
 */
-static int pagerOpenWal(Pager *pPager){
+static int pagerOpenWal(Pager *pPager, int bWal2){
  int rc = SQLITE_OK;

  assert( pPager->pWal==0 && pPager->tempFile==0 );
@@ -7599,7 +7614,7 @@ static int pagerOpenWal(Pager *pPager){
  if( rc==SQLITE_OK ){
    rc = sqlite3WalOpen(pPager->pVfs,
        pPager->fd, pPager->zWal, pPager->exclusiveMode,
-        pPager->journalSizeLimit, &pPager->pWal
+        pPager->journalSizeLimit, bWal2, &pPager->pWal
    );
 #ifdef SQLITE_ENABLE_SETLK_TIMEOUT
    if( rc==SQLITE_OK ){
@@ -7630,6 +7645,7 @@ static int pagerOpenWal(Pager *pPager){
 */
 int sqlite3PagerOpenWal(
  Pager *pPager,                  /* Pager object */
+  int bWal2,                      /* Open in wal2 mode if not already open */
  int *pbOpen                     /* OUT: Set to true if call is a no-op */
 ){
  int rc = SQLITE_OK;             /* Return code */
@@ -7646,9 +7662,9 @@ int sqlite3PagerOpenWal(
    /* Close any rollback journal previously open */
    sqlite3OsClose(pPager->jfd);

-    rc = pagerOpenWal(pPager);
+    rc = pagerOpenWal(pPager, bWal2);
    if( rc==SQLITE_OK ){
-      pPager->journalMode = PAGER_JOURNALMODE_WAL;
+      pPager->journalMode = bWal2?PAGER_JOURNALMODE_WAL2:PAGER_JOURNALMODE_WAL;
      pPager->eState = PAGER_OPEN;
    }
  }else{
@@ -7670,7 +7686,9 @@ int sqlite3PagerOpenWal(
 int sqlite3PagerCloseWal(Pager *pPager, sqlite3 *db){
  int rc = SQLITE_OK;

-  assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
+  assert( pPager->journalMode==PAGER_JOURNALMODE_WAL 
+       || pPager->journalMode==PAGER_JOURNALMODE_WAL2
+  );

  /* If the log file is not already open, but does exist in the file-system,
  ** it may need to be checkpointed before the connection can switch to
@@ -7685,7 +7703,7 @@ int sqlite3PagerCloseWal(Pager *pPager, sqlite3 *db){
      );
    }
    if( rc==SQLITE_OK && logexists ){
-      rc = pagerOpenWal(pPager);
+      rc = pagerOpenWal(pPager, 0);
    }
  }
   
@@ -82,8 +82,9 @@ typedef struct PgHdr DbPage;
 #define PAGER_JOURNALMODE_TRUNCATE    3   /* Commit by truncating journal */
 #define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */
 #define PAGER_JOURNALMODE_WAL         5   /* Use write-ahead logging */
+#define PAGER_JOURNALMODE_WAL2        6   /* Use write-ahead logging mode 2 */

-#define isWalMode(x) ((x)==PAGER_JOURNALMODE_WAL)
+#define isWalMode(x) ((x)==PAGER_JOURNALMODE_WAL || (x)==PAGER_JOURNALMODE_WAL2)

 /*
 ** The argument to this macro is a file descriptor (type sqlite3_file*).
@@ -191,7 +192,7 @@ int sqlite3PagerSharedLock(Pager *pPager);
  int sqlite3PagerCheckpoint(Pager *pPager, sqlite3*, int, int*, int*);
  int sqlite3PagerWalSupported(Pager *pPager);
  int sqlite3PagerWalCallback(Pager *pPager);
-  int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
+  int sqlite3PagerOpenWal(Pager *pPager, int, int *pisOpen);
  int sqlite3PagerCloseWal(Pager *pPager, sqlite3*);
 # ifdef SQLITE_ENABLE_SNAPSHOT
  int sqlite3PagerSnapshotGet(Pager*, sqlite3_snapshot **ppSnapshot);
@@ -290,7 +290,7 @@ const char *sqlite3JournalModename(int eMode){
  static char * const azModeName[] = {
    "delete", "persist", "off", "truncate", "memory"
 #ifndef SQLITE_OMIT_WAL
-     , "wal"
+     , "wal", "wal2"
 #endif
  };
  assert( PAGER_JOURNALMODE_DELETE==0 );
@@ -299,6 +299,7 @@ const char *sqlite3JournalModename(int eMode){
  assert( PAGER_JOURNALMODE_TRUNCATE==3 );
  assert( PAGER_JOURNALMODE_MEMORY==4 );
  assert( PAGER_JOURNALMODE_WAL==5 );
+  assert( PAGER_JOURNALMODE_WAL2==6 );
  assert( eMode>=0 && eMode<=ArraySize(azModeName) );

  if( eMode==ArraySize(azModeName) ) return 0;
@@ -90,6 +90,7 @@ const char *sqlite3TestInit(Tcl_Interp *interp){
  extern int Fts5tcl_Init(Tcl_Interp *);
  extern int SqliteRbu_Init(Tcl_Interp*);
  extern int Sqlitetesttcl_Init(Tcl_Interp*);
+  extern int Bgckpt_Init(Tcl_Interp*);
 #if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)
  extern int Sqlitetestfts3_Init(Tcl_Interp *interp);
 #endif
@@ -159,6 +160,8 @@ const char *sqlite3TestInit(Tcl_Interp *interp){
  Fts5tcl_Init(interp);
  SqliteRbu_Init(interp);
  Sqlitetesttcl_Init(interp);
+  Bgckpt_Init(interp);
+

 #if defined(SQLITE_ENABLE_FTS3) || defined(SQLITE_ENABLE_FTS4)
  Sqlitetestfts3_Init(interp);
@@ -8124,6 +8124,7 @@ case OP_JournalMode: {    /* out2 */
       || eNew==PAGER_JOURNALMODE_OFF
       || eNew==PAGER_JOURNALMODE_MEMORY
       || eNew==PAGER_JOURNALMODE_WAL
+       || eNew==PAGER_JOURNALMODE_WAL2
       || eNew==PAGER_JOURNALMODE_QUERY
  );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
@@ -8142,16 +8143,25 @@ case OP_JournalMode: {    /* out2 */
  /* Do not allow a transition to journal_mode=WAL for a database
  ** in temporary storage or if the VFS does not support shared memory
  */
-  if( eNew==PAGER_JOURNALMODE_WAL
+  if( isWalMode(eNew)
   && (sqlite3Strlen30(zFilename)==0           /* Temp file */
       || !sqlite3PagerWalSupported(pPager))   /* No shared-memory support */
  ){
    eNew = eOld;
  }

-  if( (eNew!=eOld)
-   && (eOld==PAGER_JOURNALMODE_WAL || eNew==PAGER_JOURNALMODE_WAL)
-  ){
+  if( eNew!=eOld && (isWalMode(eNew) || isWalMode(eOld)) ){
+
+    /* Prevent changing directly to wal2 from wal mode. And vice versa. */
+    if( isWalMode(eNew) && isWalMode(eOld) ){
+      rc = SQLITE_ERROR;
+      sqlite3VdbeError(p, "cannot change from %s to %s mode",
+          sqlite3JournalModename(eOld), sqlite3JournalModename(eNew)
+      );
+      goto abort_due_to_error;
+    }
+
+    /* Prevent switching into or out of wal/wal2 mode mid-transaction */
    if( !db->autoCommit || db->nVdbeRead>1 ){
      rc = SQLITE_ERROR;
      sqlite3VdbeError(p,
@@ -8161,7 +8171,7 @@ case OP_JournalMode: {    /* out2 */
      goto abort_due_to_error;
    }else{

-      if( eOld==PAGER_JOURNALMODE_WAL ){
+      if( isWalMode(eOld) ){
        /* If leaving WAL mode, close the log file. If successful, the call
        ** to PagerCloseWal() checkpoints and deletes the write-ahead-log
        ** file. An EXCLUSIVE lock may still be held on the database file
@@ -8182,7 +8192,10 @@ case OP_JournalMode: {    /* out2 */
      */
      assert( sqlite3BtreeTxnState(pBt)!=SQLITE_TXN_WRITE );
      if( rc==SQLITE_OK ){
-        rc = sqlite3BtreeSetVersion(pBt, (eNew==PAGER_JOURNALMODE_WAL ? 2 : 1));
+        /* 1==rollback, 2==wal, 3==wal2 */
+        rc = sqlite3BtreeSetVersion(pBt, 
+            1 + isWalMode(eNew) + (eNew==PAGER_JOURNALMODE_WAL2)
+        );
      }
    }
  }
@@ -2966,7 +2966,8 @@ static int vdbeCommit(sqlite3 *db, Vdbe *p){
        /* OFF       */ 0,
        /* TRUNCATE  */ 1,
        /* MEMORY    */ 0,
-        /* WAL       */ 0
+        /* WAL       */ 0,
+        /* WAL2      */ 0
      };
      Pager *pPager;   /* Pager associated with pBt */
      needXcommit = 1;
@@ -26,7 +26,7 @@
 #define CKPT_SYNC_FLAGS(X)  (((X)>>2)&0x03)

 #ifdef SQLITE_OMIT_WAL
-# define sqlite3WalOpen(x,y,z)                   0
+# define sqlite3WalOpen(w,x,y,z)                 0
 # define sqlite3WalLimit(x,y)
 # define sqlite3WalClose(v,w,x,y,z)              0
 # define sqlite3WalBeginReadTransaction(y,z)     0
@@ -45,6 +45,7 @@
 # define sqlite3WalFramesize(z)                  0
 # define sqlite3WalFindFrame(x,y,z)              0
 # define sqlite3WalFile(x)                       0
+# define sqlite3WalJournalMode(x)                0
 # undef SQLITE_USE_SEH
 #else

@@ -56,7 +57,7 @@
 typedef struct Wal Wal;

 /* Open and close a connection to a write-ahead log. */
-int sqlite3WalOpen(sqlite3_vfs*, sqlite3_file*, const char *, int, i64, Wal**);
+int sqlite3WalOpen(sqlite3_vfs*, sqlite3_file*, const char *,int,i64,int,Wal**);
 int sqlite3WalClose(Wal *pWal, sqlite3*, int sync_flags, int, u8 *);

 /* Set the limiting size of a WAL file. */
@@ -147,6 +148,9 @@ int sqlite3WalFramesize(Wal *pWal);
 /* Return the sqlite3_file object for the WAL file */
 sqlite3_file *sqlite3WalFile(Wal *pWal);

+/* Return the journal mode (WAL or WAL2) used by this Wal object. */
+int sqlite3WalJournalMode(Wal *pWal);
+
 #ifdef SQLITE_ENABLE_SETLK_TIMEOUT
 int sqlite3WalWriteLock(Wal *pWal, int bLock);
 void sqlite3WalDb(Wal *pWal, sqlite3 *db);
@@ -47,7 +47,7 @@ db close
 forcecopy test.db test.db-template

 set unreadable_version 02
-ifcapable wal { set unreadable_version 03 }
+ifcapable wal { set unreadable_version 04 }
 do_test corruptA-2.1 {
  forcecopy test.db-template test.db
  hexio_write test.db 19 $unreadable_version   ;# the read format number
@@ -465,18 +465,21 @@ lappend ::testsuitelist xxx
 test_suite "coverage-wal" -description {
  Coverage tests for file wal.c.
 } -files {
-  wal.test wal2.test wal3.test wal4.test wal5.test
+  wal2big.test wal2recover.test wal2rewrite.test
+  wal2simple.test wal2snapshot.test wal2.test
+  wal3.test wal4.test wal5.test
  wal64k.test wal6.test wal7.test wal8.test wal9.test
-  walbak.test walbig.test walblock.test walcksum.test walcrash2.test
-  walcrash3.test walcrash4.test walcrash.test walfault.test walhook.test
-  walmode.test walnoshm.test waloverwrite.test walpersist.test 
-  walprotocol2.test walprotocol.test walro2.test walrofault.test 
-  walro.test walshared.test walslow.test walvfs.test
-  walfault2.test
-  nockpt.test
-
+  walbak.test walbig.test walblock.test walcksum.test 
+  walfault.test walhook.test walmode.test walnoshm.test
+  waloverwrite.test walpersist.test walprotocol2.test
+  walprotocol.test walro2.test walrofault.test walro.test
+  walshared.test walslow.test wal.test
+  wal2savepoint.test wal2lock.test wal2recover2.test
+  walvfs.test walfault2.test nockpt.test
  snapshot2.test snapshot3.test snapshot4.test
  snapshot_fault.test snapshot.test snapshot_up.test
+  walcrash2.test walcrash3.test walcrash4.test walcrash.test
+  wal2fault.test
 } 

 test_suite "coverage-pager" -description {
@@ -1033,6 +1036,23 @@ test_suite "wal" -description {
  fts3c.test   fts3d.test   fts3e.test   fts3query.test 
 }

+test_suite "wal2" -description {
+  Run tests with journal_mode=WAL2
+} -initialize {
+  set ::G(savepoint6_iterations) 100
+} -shutdown {
+  unset -nocomplain ::G(savepoint6_iterations)
+} -files {
+  savepoint.test     savepoint2.test     savepoint6.test
+  trans.test         avtrans.test
+
+  fts3aa.test  fts3ab.test  fts3ac.test  fts3ad.test
+  fts3ae.test  fts3af.test  fts3ag.test  fts3ah.test
+  fts3ai.test  fts3aj.test  fts3ak.test  fts3al.test
+  fts3am.test  fts3an.test  fts3ao.test  fts3b.test
+  fts3c.test   fts3d.test   fts3e.test   fts3query.test 
+}
+
 test_suite "rtree" -description {
  All R-tree related tests. Provides coverage of source file rtree.c.
 } -files [glob -nocomplain $::testdir/../ext/rtree/*.test]
@@ -41,7 +41,7 @@ do_test rdonly-1.1.1 {
  sqlite3_db_readonly db main
 } {0}

-# Changes the write version from 1 to 3.  Verify that the database
+# Changes the write version from 1 to 4.  Verify that the database
 # can be read but not written.
 #
 do_test rdonly-1.2 {
@@ -49,7 +49,7 @@ do_test rdonly-1.2 {
  hexio_get_int [hexio_read test.db 18 1]
 } 1
 do_test rdonly-1.3 {
-  hexio_write test.db 18 03
+  hexio_write test.db 18 04
  sqlite3 db test.db
  execsql {
    SELECT * FROM t1;
@@ -83,7 +83,7 @@ do_test rdonly-1.5 {
 # the database is read-only until after it is locked.
 #
 set ro_version 02
-ifcapable wal { set ro_version 03 }
+ifcapable wal { set ro_version 04 }
 do_test rdonly-1.6 {
  hexio_write test.db 18 $ro_version     ; # write-version
  hexio_write test.db 24 11223344        ; # change-counter
@@ -30,6 +30,7 @@ do_test savepoint-1.1 {
    RELEASE sp1;
  }
 } {}
+wal_check_journal_mode savepoint-1.1
 do_test savepoint-1.2 {
  execsql {
    SAVEPOINT sp1;
@@ -807,7 +808,8 @@ do_test savepoint-11.6 {
 integrity_check savepoint-11.7
 do_test savepoint-11.8 {
  execsql { ROLLBACK }
-  execsql { PRAGMA wal_checkpoint }
+  db close
+  sqlite3 db test.db
  file size test.db
 } {8192}

@@ -553,6 +553,7 @@ proc reset_db {} {
  forcedelete test.db
  forcedelete test.db-journal
  forcedelete test.db-wal
+  forcedelete test.db-wal2
  sqlite3 db ./test.db
  set ::DB [sqlite3_connection_pointer db]
  if {[info exists ::SETUP_SQL]} {
@@ -2306,17 +2307,32 @@ proc drop_all_indexes {{db db}} {
 #     Returns true if this test should be run in WAL mode. False otherwise.
 #
 proc wal_is_wal_mode {} {
-  expr {[permutation] eq "wal"}
+  if {[permutation] eq "wal"} { return 1 }
+  if {[permutation] eq "wal2"} { return 2 }
+  return 0
 }
 proc wal_set_journal_mode {{db db}} {
-  if { [wal_is_wal_mode] } {
-    $db eval "PRAGMA journal_mode = WAL"
+  switch -- [wal_is_wal_mode] {
+    0 {
+    }
+
+    1 {
+      $db eval "PRAGMA journal_mode = WAL"
+    }
+
+    2 {
+      $db eval "PRAGMA journal_mode = WAL2"
+    }
  }
 }
 proc wal_check_journal_mode {testname {db db}} {
  if { [wal_is_wal_mode] } {
    $db eval { SELECT * FROM sqlite_master }
-    do_test $testname [list $db eval "PRAGMA main.journal_mode"] {wal}
+    set expected "wal"
+    if {[wal_is_wal_mode]==2} {
+      set expected "wal2"
+    }
+    do_test $testname [list $db eval "PRAGMA main.journal_mode"] $expected
  }
 }

@@ -282,11 +282,11 @@ ifcapable wal {
      INSERT INTO t2 VALUES('x', 'y');
    }
    lsort [array names ::T1]
-  } {test.db1 test.db1-journal test.db1-wal}
+  } {test.db1 test.db1-journal test.db1-wal test.db1-wal2}
  
  do_test 5.1.2 {
    lsort [array names ::T2]
-  } {test.db2 test.db2-journal test.db2-wal}
+  } {test.db2 test.db2-journal test.db2-wal test.db2-wal2}
  db close
  
  tvfs1 delete
@@ -1175,7 +1175,7 @@ foreach {tn pgsz works} {
  9  32768    1
 10  65536    1
 11 131072    0
- 11   1016    0
+ 12   1016    0
 } {

  if {$::SQLITE_MAX_PAGE_SIZE < $pgsz} {
@@ -1185,14 +1185,14 @@ foreach {tn pgsz works} {
  for {set pg 1} {$pg <= 3} {incr pg} {
    forcecopy testX.db test.db
    forcedelete test.db-wal
-  
+
    # Check that the database now exists and consists of three pages. And
    # that there is no associated wal file.
    #
    do_test wal-18.2.$tn.$pg.1 { file exists test.db-wal } 0
    do_test wal-18.2.$tn.$pg.2 { file exists test.db } 1
    do_test wal-18.2.$tn.$pg.3 { file size test.db } [expr 1024*3]
-  
+
    do_test wal-18.2.$tn.$pg.4 {

      # Create a wal file that contains a single frame (database page
@@ -1224,16 +1224,16 @@ foreach {tn pgsz works} {
      puts -nonewline $fd $framehdr
      puts -nonewline $fd $framebody
      close $fd
-  
+
      file size test.db-wal
    } [wal_file_size 1 $pgsz]
-  
+
    do_test wal-18.2.$tn.$pg.5 {
      sqlite3 db test.db
      set rc [catch { db one {PRAGMA integrity_check} } msg]
      expr { $rc!=0 || $msg!="ok" }
    } $works
-  
+ 
    db close
  }
 }
@@ -0,0 +1,73 @@
+# 2017 September 19
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# TESTRUNNER: slow
+#
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2big
+ifcapable !wal {finish_test ; return }
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c);
+  CREATE INDEX t1a ON t1(a);
+  CREATE INDEX t1b ON t1(b);
+  CREATE INDEX t1c ON t1(c);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 10000000;
+
+  WITH s(i) AS (
+    SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<200000
+  )
+  INSERT INTO t1 SELECT random(), random(), random() FROM s;
+} {wal2 10000000}
+
+do_execsql_test 1.1 {
+  WITH s(i) AS (
+    SELECT 1 UNION ALL SELECT i+1 FROM s WHERE i<200000
+  )
+  INSERT INTO t1 SELECT random(), random(), random() FROM s;
+}
+
+do_test 1.2 {
+  list [expr [file size test.db-wal]>10000000] \
+       [expr [file size test.db-wal2]>10000000]
+} {1 1}
+
+do_test 1.3 {
+  sqlite3 db2 test.db
+  execsql {
+    SELECT count(*) FROM t1;
+    PRAGMA integrity_check;
+  } db2
+} {400000 ok}
+
+do_test 1.4 {
+  db2 close
+  forcecopy test.db test.db2
+  forcecopy test.db-wal test.db2-wal
+  forcecopy test.db-wal2 test.db2-wal2
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    PRAGMA integrity_check;
+  }
+} {400000 ok}
+
+finish_test
@@ -0,0 +1,52 @@
+# 2010 May 03
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/malloc_common.tcl
+source $testdir/lock_common.tcl
+
+ifcapable !wal {finish_test ; return }
+set testprefix wal2fault
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x,y);
+  PRAGMA journal_mode = wal2;
+  WITH s(i) AS ( SELECT 100 UNION ALL SELECT i-1 FROM s WHERE (i-1)>0 )
+  INSERT INTO t1 SELECT i, randomblob(i) FROM s;
+  WITH s(i) AS ( SELECT 100 UNION ALL SELECT i-1 FROM s WHERE (i-1)>0 )
+  INSERT INTO t1 SELECT i, randomblob(i) FROM s;
+} {wal2}
+
+do_test 1.1 {
+  expr [file size test.db-wal]>10000
+} {1}
+faultsim_save_and_close
+
+do_faultsim_test 1 -prep {
+  faultsim_restore_and_reopen
+  execsql {
+    PRAGMA journal_size_limit = 10000;
+    SELECT count(*) FROM sqlite_master;
+  }
+} -body {
+  execsql {
+    INSERT INTO t1 VALUES(1, 2);
+  }
+} -test {
+  faultsim_test_result {0 {}}
+}
+
+finish_test
@@ -0,0 +1,106 @@
+# 2018 December 15
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2lock
+ifcapable !wal {finish_test ; return }
+
+db close
+testvfs tvfs 
+sqlite3 db test.db -vfs tvfs
+
+do_execsql_test 1.0 {
+  PRAGMA journal_mode = wal2;
+  CREATE TABLE y1(y, yy);
+  CREATE INDEX y1y ON y1(y);
+  CREATE INDEX y1yy ON y1(yy);
+  INSERT INTO y1 VALUES(1, 2), (3, 4), (5, 6);
+} {wal2}
+
+tvfs script vfs_callback
+tvfs filter xShmLock
+
+set ::lock [list]
+proc vfs_callback {func file name lock} {
+  lappend ::lock $lock
+  return SQLITE_OK
+}
+
+do_execsql_test 1.1.1 {
+  SELECT * FROM y1
+} {1 2 3 4 5 6}
+do_test 1.1.2 {
+  set ::lock
+} {{4 1 lock shared} {4 1 unlock shared}}
+
+set ::bFirst 1
+proc vfs_callback {func file name lock} {
+  if {$::bFirst} {
+    set ::bFirst 0
+    return SQLITE_BUSY
+  }
+  return SQLITE_OK
+}
+do_execsql_test 1.2 {
+  SELECT * FROM y1
+} {1 2 3 4 5 6}
+
+set ::bFirst 1
+proc vfs_callback {func file name lock} {
+  if {$::bFirst} {
+    set ::bFirst 0
+    return SQLITE_IOERR
+  }
+  return SQLITE_OK
+}
+do_catchsql_test 1.3 {
+  SELECT * FROM y1
+} {1 {disk I/O error}}
+
+puts "# Warning: This next test case causes SQLite to call xSleep(1) 100 times."
+puts "# Normally this equates to a delay of roughly 10 seconds, but if SQLite"
+puts "# is built on unix without HAVE_USLEEP defined, it may be much longer."
+proc vfs_callback {func file name lock} { return SQLITE_BUSY }
+do_catchsql_test 1.4 {
+  SELECT * FROM y1
+} {1 {locking protocol}}
+proc vfs_callback {func file name lock} { return SQLITE_OK }
+
+sqlite3 db2 test.db -vfs tvfs
+set ::bFirst 1
+
+proc vfs_callback {func file name lock} {
+  if {$::bFirst} {
+    set ::bFirst 0
+    db2 eval { INSERT INTO y1 VALUES(7, 8) }
+  }
+}
+
+do_execsql_test 1.5.1 {
+  SELECT * FROM y1
+} {1 2 3 4 5 6 7 8}
+do_execsql_test 1.5.2 {
+  SELECT * FROM y1
+} {1 2 3 4 5 6 7 8}
+
+db close
+db2 close
+tvfs delete
+finish_test
@@ -0,0 +1,81 @@
+# 2017 September 19
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2openclose
+ifcapable !wal {finish_test ; return }
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c);
+  PRAGMA journal_mode = wal2;
+  PRAGMA wal_autocheckpoint = 0;
+  PRAGMA journal_size_limit = 75000;
+} {wal2 0 75000}
+
+do_test 1.1 {
+  for {set ii 1} {$ii <= 200} {incr ii} {
+    execsql {
+      INSERT INTO t1 VALUES($ii, $ii, $ii);
+    }
+  }
+  expr ([file size test.db-wal2] - 75000) > 30000
+} {1}
+
+do_test 1.2 {
+  db close
+  list [file exists test.db-wal] [file exists test.db-wal2]
+} {0 0}
+
+sqlite3 db test.db
+do_execsql_test 1.3 {
+  SELECT sum(c) FROM t1
+} {20100}
+db close
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE t1(a, b, c);
+  PRAGMA journal_mode = wal2;
+  INSERT INTO t1 VALUES(1, 2, 3);
+} {wal2}
+db_save_and_close
+
+db_restore_and_reopen
+do_execsql_test 2.1 {
+  SELECT * FROM t1;
+} {1 2 3}
+
+do_test 2.2 {
+  sqlite3 db2 test.db
+  db2 eval {INSERT INTO t1 VALUES(4, 5, 6)}
+  db2 close
+} {}
+
+breakpoint
+db close
+sqlite3 db test.db
+do_execsql_test 2.2 {
+  SELECT * FROM t1;
+} {1 2 3 4 5 6}
+
+
+
+finish_test
@@ -0,0 +1,271 @@
+# 2018 December 13
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2recover
+ifcapable !wal {finish_test ; return }
+
+proc db_copy {from to} {
+  forcecopy $from $to
+  forcecopy ${from}-wal ${to}-wal
+  forcecopy ${from}-wal2 ${to}-wal2
+}
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c);
+  CREATE INDEX t1a ON t1(a);
+  CREATE INDEX t1b ON t1(b);
+  CREATE INDEX t1c ON t1(c);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 15000;
+  PRAGMA wal_autocheckpoint = 0;
+} {wal2 15000 0}
+
+do_test 1.1 {
+  for {set i 1} {$i <= 1000} {incr i} {
+    execsql { INSERT INTO t1 VALUES(random(), random(), random()) }
+    db_copy test.db test.db2
+    sqlite3 db2 test.db
+    set res [execsql {
+      SELECT count(*) FROM t1;
+      PRAGMA integrity_check;
+    } db2]
+    db2 close
+    if {$res != [list $i ok]} {
+      error "failure on iteration $i"
+    }
+  }
+  set {} {}
+} {}
+
+#--------------------------------------------------------------------------
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE t1(x UNIQUE);
+  CREATE TABLE t2(x UNIQUE);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 10000;
+  PRAGMA wal_autocheckpoint = 0;
+  BEGIN;
+    INSERT INTO t1 VALUES(randomblob(4000));
+    INSERT INTO t1 VALUES(randomblob(4000));
+    INSERT INTO t1 VALUES(randomblob(4000));
+  COMMIT;
+  BEGIN;
+    INSERT INTO t2 VALUES(randomblob(4000));
+    INSERT INTO t2 VALUES(randomblob(4000));
+    INSERT INTO t2 VALUES(randomblob(4000));
+  COMMIT;
+} {wal2 10000 0}
+do_test 2.0.1 {
+  list [file size test.db] [file size test.db-wal] [file size test.db-wal2]
+} {5120 28328 28328}
+
+# Test recovery with both wal files intact.
+#
+do_test 2.1 {
+  db_copy test.db test.db2
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+    PRAGMA integrity_check;
+  } db2
+} {3 3 ok}
+
+do_test 2.2 {
+  db2 close
+  db_copy test.db test.db2
+  hexio_write test.db2-wal 16 12345678
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+  } db2
+} {0 3}
+
+do_test 2.3 {
+  db2 close
+  db_copy test.db test.db2
+  hexio_write test.db2-wal2 16 12345678
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+    PRAGMA integrity_check;
+  } db2
+} {3 0 ok}
+
+do_test 2.4 {
+  db2 close
+  db_copy test.db test.db2
+  forcecopy test.db-wal test.db2-wal2
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+    PRAGMA integrity_check;
+  } db2
+} {3 0 ok}
+
+do_test 2.5 {
+  db2 close
+  db_copy test.db test.db2
+  forcecopy test.db-wal  test.db2-wal2
+  forcecopy test.db-wal2  test.db2-wal
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+    PRAGMA integrity_check;
+  } db2
+} {3 3 ok}
+
+do_test 2.6 {
+  db2 close
+  db_copy test.db test.db2
+  forcecopy test.db-wal test.db2-wal2
+  close [open test.db-wal w]
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+    PRAGMA integrity_check;
+  } db2
+} {3 0 ok}
+
+do_test 2.7 {
+  db2 close
+  db_copy test.db test.db2
+  forcedelete test.db2-wal
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT count(*) FROM t1;
+    SELECT count(*) FROM t2;
+    PRAGMA integrity_check;
+  } db2
+} {0 0 ok}
+db2 close
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE t1(a TEXT, b TEXT, c TEXT);
+  CREATE INDEX t1a ON t1(a);
+  CREATE INDEX t1b ON t1(b);
+  CREATE INDEX t1c ON t1(c);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 10000;
+  PRAGMA wal_autocheckpoint = 0;
+  PRAGMA cache_size = 5;
+} {wal2 10000 0}
+
+do_execsql_test 3.1 {
+  WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 200)
+  INSERT INTO t1 SELECT i, i, i FROM s;
+
+  INSERT INTO t1 VALUES(201, 201, 201);
+} {}
+
+do_test 3.2 {
+  list [file size test.db] [file size test.db-wal] [file size test.db-wal2]
+} {5120 15752 4224}
+
+do_test 3.3 {
+  forcecopy test.db test.db2
+  forcecopy test.db-wal test.db2-wal
+  forcecopy test.db-wal2 test.db2-wal2
+  sqlite3 db2 test.db2
+  execsql {
+    PRAGMA journal_size_limit = 10000;
+    PRAGMA wal_autocheckpoint = 0;
+    PRAGMA cache_size = 5;
+    BEGIN;
+      WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 200)
+      INSERT INTO t1 SELECT i, i, i FROM s;
+  } db2
+  list [file size test.db2] [file size test.db2-wal] [file size test.db2-wal2]
+} {5120 15752 23088}
+
+
+if {$tcl_platform(platform)!="windows"} {
+  # These cannot be run under windows, as the *-shm file may not be read
+  # while it is locked by the database connection. 
+  do_test 3.4 {
+    set fd [open test.db2-shm]
+    fconfigure $fd -translation binary
+    set data [read $fd]
+    close $fd
+  
+    set fd [open test.db-shm w]
+    fconfigure $fd -translation binary
+    puts -nonewline $fd $data
+    close $fd
+  
+    execsql {
+      WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 10)
+        INSERT INTO t1 SELECT i, i, i FROM s;
+      SELECT count(*) FROM t1;
+      PRAGMA integrity_check;
+    }
+  } {211 ok}
+  
+  do_test 3.5 {
+    list [file size test.db] [file size test.db-wal] [file size test.db-wal2]
+  } {5120 15752 18896}
+}
+
+#-------------------------------------------------------------------------
+#
+reset_db
+do_execsql_test 4.0 {
+  PRAGMA journal_mode = wal2;
+  CREATE TABLE xyz(x, y, z);
+  INSERT INTO xyz VALUES('x', 'y', 'z');
+} {wal2}
+db close
+do_test 4.1 {
+  close [open test.db-wal w]
+  file mkdir test.db-wal2
+  sqlite3 db test.db
+  catchsql { SELECT * FROM xyz }
+} {1 {unable to open database file}}
+db close
+file delete test.db-wal2
+db2 close
+
+do_test 4.2 {
+  sqlite3 db test.db
+  execsql { 
+    INSERT INTO xyz VALUES('a', 'b', 'c');
+  }
+  forcecopy test.db test.db2
+  forcecopy test.db-wal test.db2-wal
+  forcedelete test.db2-wal2
+  file mkdir test.db2-wal2
+  sqlite3 db2 test.db2
+  catchsql { SELECT * FROM xyz } db2
+} {1 {unable to open database file}}
+db2 close
+file delete test.db2-wal2
+
+
+finish_test
@@ -0,0 +1,273 @@
+# 2018 December 13
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2recover2
+ifcapable !wal {finish_test ; return }
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x);
+  CREATE TABLE t2(x);
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t1 SELECT i FROM s;
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t2 SELECT i FROM s;
+
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 10000;
+} {wal2 10000}
+
+set ::L 1125750
+set ::M 1126500
+set ::H 1127250
+
+do_execsql_test 1.1 {
+  UPDATE t1 SET x=x+1;
+  UPDATE t2 SET x=x+1 WHERE rowid<=750;
+
+  SELECT sum(x) FROM t1;
+  SELECT sum(x) FROM t2;
+} [list $H $M]
+
+do_test 1.2 {
+  list [file size test.db] [file size test.db-wal] [file size test.db-wal2]
+} {31744 14704 7368}
+
+proc cksum {zIn data} {
+  if {[string length $zIn]==0} {
+    set s0 0
+    set s1 0
+  } else {
+    set s0 [hexio_get_int [string range $zIn 0 7]]
+    set s1 [hexio_get_int [string range $zIn 8 15]]
+  }
+  set n [expr [string length $data] / 8]
+
+  for {set i 0} {$i < $n} {incr i 2} {
+    set x0 [hexio_get_int -l [string range $data [expr $i*8]   [expr $i*8+7]]]
+    set x1 [hexio_get_int -l [string range $data [expr $i*8+8] [expr $i*8+8+7]]]
+
+    set s0 [expr ($s0 + $x0 + $s1) & 0xFFFFFFFF]
+    set s1 [expr ($s1 + $x1 + $s0) & 0xFFFFFFFF]
+  }
+
+  return "[hexio_render_int32 $s0][hexio_render_int32 $s1]"
+}
+
+proc fix_wal_cksums {file} {
+  # Fix the checksum on the wal header.
+  set data [hexio_read $file 0 32]
+  set cksum [cksum {} [string range $data 0 47]]
+  set salt [hexio_read $file 16 8]
+  hexio_write $file 24 $cksum
+
+  # Fix the checksums for all pages in the wal file.
+  set pgsz [hexio_get_int [hexio_read $file 8 4]]
+  set sz [file size $file]
+  for {set off 32} {$off < $sz} {incr off [expr $pgsz+24]} {
+    set e [hexio_read $file $off 8]
+    set cksum [cksum $cksum $e]
+
+    set p [hexio_read $file [expr $off+24] $pgsz]
+    set cksum [cksum $cksum $p]
+
+    hexio_write $file [expr $off+8] $salt
+    hexio_write $file [expr $off+16] $cksum
+  }
+}
+
+proc wal_incr_hdrfield {file field} {
+  switch -- $field {
+    nCkpt { set offset 12 }
+    salt0 { set offset 16 }
+    salt1 { set offset 20 }
+    default {
+      error "unknown field $field - should be \"nCkpt\", \"salt0\" or \"salt1\""
+    }
+  }
+
+  # Increment the value in the wal header.
+  set v [hexio_get_int [hexio_read $file $offset 4]]
+  incr v
+  hexio_write $file $offset [hexio_render_int32 $v]
+  
+  # Fix various checksums
+  fix_wal_cksums $file
+}
+
+proc wal_set_nckpt {file val} {
+  # Increment the value in the wal header.
+  hexio_write $file 12 [hexio_render_int32 $val]
+  
+  # Fix various checksums
+  fix_wal_cksums $file
+}
+
+proc wal_set_follow {file prevfile} {
+  set pgsz [hexio_get_int [hexio_read $prevfile 8 4]]
+  set sz [file size $prevfile]
+  set cksum [hexio_read $prevfile [expr $sz-$pgsz-8] 8]
+
+  hexio_write $file 16 $cksum
+  fix_wal_cksums $file
+}
+
+foreach {tn file field} {
+  1 test.db2-wal    salt0
+  2 test.db2-wal    salt1
+  3 test.db2-wal    nCkpt
+  4 test.db2-wal2   salt0
+  5 test.db2-wal2   salt1
+  6 test.db2-wal2   nCkpt
+} {
+  do_test 1.3.$tn {
+    forcecopy test.db test.db2
+    forcecopy test.db-wal test.db2-wal
+    forcecopy test.db-wal2 test.db2-wal2
+    wal_incr_hdrfield $file $field
+    sqlite3 db2 test.db2
+    execsql {
+      SELECT sum(x) FROM t1;
+      SELECT sum(x) FROM t2;
+    } db2
+  } [list $H $L]
+  db2 close
+}
+
+do_test 1.4 {
+  forcecopy test.db test.db2
+  forcecopy test.db-wal2 test.db2-wal
+  forcedelete test.db2-wal2
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT sum(x) FROM t1;
+    SELECT sum(x) FROM t2;
+  } db2
+} [list $L $M]
+
+do_test 1.5 {
+  db2 close
+  forcecopy test.db test.db2
+  forcecopy test.db-wal2 test.db2-wal
+  forcecopy test.db-wal test.db2-wal2
+  sqlite3 db2 test.db2
+  execsql {
+    SELECT sum(x) FROM t1;
+    SELECT sum(x) FROM t2;
+  } db2
+} [list $H $M]
+
+db2 close
+foreach {tn file field} {
+  1 test.db2-wal    salt0
+  2 test.db2-wal    salt1
+  3 test.db2-wal2   salt0
+  4 test.db2-wal2   salt1
+} {
+  do_test 1.6.$tn {
+    forcecopy test.db test.db2
+    forcecopy test.db-wal2 test.db2-wal
+    forcecopy test.db-wal test.db2-wal2
+    wal_incr_hdrfield $file $field
+    sqlite3 db2 test.db2
+    execsql {
+      SELECT sum(x) FROM t1;
+      SELECT sum(x) FROM t2;
+    } db2
+  } [list $H $L]
+  db2 close
+}
+
+foreach {tn nCkpt1 nCkpt2 res} [list \
+  1   2 1   "$H $M"                  \
+  2   2 2   "$L $M"                  \
+  3   3 1   "$H $L"                  \
+  4   15 14 "$H $M"                  \
+  5   0 15  "$H $M"                  \
+  6   1 15  "$L $M"                  \
+] {
+  do_test 1.7.$tn {
+    forcecopy test.db test.db2
+    forcecopy test.db-wal2 test.db2-wal
+    forcecopy test.db-wal test.db2-wal2
+
+    wal_set_nckpt test.db2-wal2 $nCkpt2
+    wal_set_nckpt test.db2-wal  $nCkpt1
+    wal_set_follow test.db2-wal test.db2-wal2
+
+
+    sqlite3 db2 test.db2
+    execsql {
+      SELECT sum(x) FROM t1;
+      SELECT sum(x) FROM t2;
+    } db2
+  } $res
+  db2 close
+}
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 1.8.1 {
+  PRAGMA autovacuum = 0;
+  PRAGMA page_size = 4096;
+  CREATE TABLE t1(x);
+  CREATE TABLE t2(x);
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t1 SELECT i FROM s;
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t2 SELECT i FROM s;
+
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 10000;
+
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t2 SELECT i FROM s;
+} {wal2 10000}
+
+do_test 1.8.2 {
+  list [file size test.db-wal] [file size test.db-wal2]
+} {24752 0}
+
+do_execsql_test 1.8.3 { PRAGMA user_version = 123 }
+do_test 1.8.4 {
+  list [file size test.db-wal] [file size test.db-wal2]
+} {24752 4152}
+
+do_test 1.8.5 {
+  hexio_write test.db-wal2 [expr 56+16] 0400
+  fix_wal_cksums test.db-wal2
+} {}
+
+ifcapable oversize_cell_check {
+  set msg {database disk image is malformed}
+} else {
+  set msg {malformed database schema (?)}
+}
+
+do_test 1.8.6 {
+  forcecopy test.db test.db2
+  forcecopy test.db-wal test.db2-wal
+  forcecopy test.db-wal2 test.db2-wal2
+  sqlite3 db2 test.db2
+  catchsql { SELECT * FROM sqlite_master } db2
+} [list 1 $msg]
+db2 close
+
+finish_test
@@ -0,0 +1,52 @@
+# 2022 June 28
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2recover3
+ifcapable !wal {finish_test ; return }
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(x);
+  CREATE TABLE t2(x);
+  PRAGMA journal_mode = wal2;
+  PRAGMA wal_autocheckpoint = 0;
+  PRAGMA journal_size_limit = 10000;
+} {wal2 0 10000}
+
+do_execsql_test 1.1 {
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t1 SELECT i FROM s;
+  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<1500 )
+    INSERT INTO t2 SELECT i FROM s;
+}
+
+db_save_and_close
+set fd [open sv_test.db-wal2 r+]
+seek $fd 4000
+puts -nonewline $fd 0
+close $fd
+
+db_restore_and_reopen
+do_execsql_test 1.2 {
+  SELECT sql FROM sqlite_schema;
+} {{CREATE TABLE t1(x)} {CREATE TABLE t2(x)}}
+
+finish_test
+
@@ -0,0 +1,92 @@
+# 2017 September 19
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2rewrite
+ifcapable !wal {finish_test ; return }
+
+proc filesize {filename} {
+  if {[file exists $filename]} {
+    return [file size $filename]
+  }
+  return 0
+}
+
+foreach {tn jrnlmode} {
+  1 wal
+  2 wal2
+} {
+  reset_db
+  execsql "PRAGMA journal_mode = $jrnlmode"
+  do_execsql_test $tn.1 {
+    PRAGMA journal_size_limit = 10000;
+    PRAGMA cache_size = 5;
+    PRAGMA wal_autocheckpoint = 10;
+  
+    CREATE TABLE t1(a INTEGER PRIMARY KEY, b INTEGER, c BLOB);
+    CREATE INDEX t1b ON t1(b);
+    CREATE INDEX t1c ON t1(c);
+  
+    WITH s(i) AS (
+      SELECT 1 UNION SELECT i+1 FROM s WHERE i<10
+    )
+    INSERT INTO t1 SELECT i, i, randomblob(800) FROM s;
+  } {10000 10}
+  
+  for {set i 0} {$i < 4} {incr i} {
+    do_execsql_test $tn.$i.1 {
+      UPDATE t1 SET c=randomblob(800) WHERE (b%10)==5 AND ($i%2)
+    }
+    do_execsql_test $tn.$i.2 {
+      BEGIN;
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+      UPDATE t1 SET b=b+10, c=randomblob(800);
+    }
+    execsql COMMIT
+
+    do_test $tn.$i.3 { expr [filesize test.db-wal]  < 100000 } 1
+    do_test $tn.$i.4 { expr [filesize test.db-wal2] < 100000 } 1
+
+    set sum [db eval {SELECT sum(b), md5sum(c) FROM t1}]
+
+    do_test $tn.$i.5 {
+      foreach f [glob -nocomplain test.db2*] {forcedelete $f}
+      foreach f [glob -nocomplain test.db*] {
+        forcecopy $f [string map {test.db test.db2} $f]
+      }
+
+      sqlite3 db2 test.db2
+      db2 eval {SELECT sum(b), md5sum(c) FROM t1}
+    } $sum
+    db2 close
+  }
+}
+    
+
+
+finish_test
@@ -0,0 +1,62 @@
+# 2017 September 19
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2rollback
+ifcapable !wal {finish_test ; return }
+
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c);
+  CREATE TABLE t2(a, b, c);
+  CREATE INDEX i1 ON t1(a);
+  CREATE INDEX i2 ON t1(b);
+  PRAGMA journal_mode = wal2;
+  PRAGMA cache_size = 5;
+  PRAGMA journal_size_limit = 10000;
+  WITH s(i) AS (
+    SELECT 1 UNION ALL SELECT i+1 FROM s LIMIT 1000
+  )
+  INSERT INTO t1 SELECT i, i, randomblob(200) FROM s;
+} {wal2 10000}
+
+do_test 1.1 {
+  expr [file size test.db-wal] > 10000
+} 1
+
+do_test 1.2 {
+  execsql {
+    BEGIN;
+      UPDATE t1 SET b=b+1;
+      INSERT INTO t2 VALUES(1,2,3);
+  }
+  expr [file size test.db-wal2] > 10000
+} {1}
+
+breakpoint
+do_execsql_test 1.3 {
+  ROLLBACK;
+  SELECT * FROM t2;
+  SELECT count(*) FROM t1 WHERE a=b;
+  PRAGMA integrity_check;
+} {1000 ok}
+
+
+
+finish_test
@@ -0,0 +1,73 @@
+# 2018 December 13
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2savepoint
+ifcapable !wal {finish_test ; return }
+
+reset_prng_state
+do_execsql_test 1.0 {
+  CREATE TABLE t1(a, b, c);
+  CREATE INDEX t1a ON t1(a);
+  CREATE INDEX t1b ON t1(b);
+  CREATE INDEX t1c ON t1(c);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 15000;
+  PRAGMA wal_autocheckpoint = 0;
+  PRAGMA cache_size = 5;
+} {wal2 15000 0}
+
+do_execsql_test 1.1 {
+  WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 200)
+  INSERT INTO t1 SELECT random(), random(), random() FROM s;
+} {}
+
+do_test 1.2 {
+  list [file size test.db] [file size test.db-wal] [file size test.db-wal2]
+} {5120 23088 0}
+
+do_execsql_test 1.3 {
+  BEGIN;
+    SAVEPOINT abc;
+      WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 100)
+      INSERT INTO t1 SELECT random(), random(), random() FROM s;
+    ROLLBACK TO abc;
+    WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 10)
+    INSERT INTO t1 SELECT random(), random(), random() FROM s;
+  COMMIT;
+  SELECT count(*) FROM t1;
+  PRAGMA integrity_check;
+} {210 ok}
+
+do_execsql_test 1.4 {
+  BEGIN;
+    SAVEPOINT abc;
+      WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 100)
+      INSERT INTO t1 SELECT random(), random(), random() FROM s;
+    ROLLBACK TO abc;
+    WITH s(i) AS ( SELECT 1 UNION ALL SELECT i+1 FROM s where i < 10)
+    INSERT INTO t1 SELECT random(), random(), random() FROM s;
+  COMMIT;
+  SELECT count(*) FROM t1;
+  PRAGMA integrity_check;
+} {220 ok}
+
+
+finish_test
@@ -0,0 +1,543 @@
+# 2017 September 19
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+source $testdir/lock_common.tcl
+source $testdir/malloc_common.tcl
+source $testdir/wal_common.tcl
+
+set testprefix wal2simple
+ifcapable !wal {finish_test ; return }
+
+#-------------------------------------------------------------------------
+# The following tests verify that a client can switch in and out of wal
+# and wal2 mode. But that it is not possible to change directly from wal
+# to wal2, or from wal2 to wal mode.
+#
+do_execsql_test 1.1.0 {
+  PRAGMA journal_mode = wal2
+} {wal2}
+execsql { SELECT * FROM sqlite_master} 
+do_execsql_test 1.x {
+  PRAGMA journal_mode;
+  PRAGMA main.journal_mode;
+} {wal2 wal2}
+db close
+do_test 1.1.1 { file size test.db } {1024}
+do_test 1.1.2 { hexio_read test.db 18 2 } 0303
+
+sqlite3 db test.db
+do_execsql_test 1.2.0 {
+  SELECT * FROM sqlite_master;
+  PRAGMA journal_mode = delete;
+} {delete}
+db close
+do_test 1.2.1 { file size test.db } {1024}
+do_test 1.2.2 { hexio_read test.db 18 2 } 0101
+
+sqlite3 db test.db
+do_execsql_test 1.3.0 {
+  SELECT * FROM sqlite_master;
+  PRAGMA journal_mode = wal;
+} {wal}
+db close
+do_test 1.3.1 { file size test.db } {1024}
+do_test 1.3.2 { hexio_read test.db 18 2 } 0202
+
+sqlite3 db test.db
+do_catchsql_test 1.4.0 {
+  PRAGMA journal_mode = wal2;
+} {1 {cannot change from wal to wal2 mode}}
+do_execsql_test 1.4.1 {
+  PRAGMA journal_mode = wal;
+  PRAGMA journal_mode = delete;
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_mode = wal2;
+} {wal delete wal2 wal2}
+do_catchsql_test 1.4.2 {
+  PRAGMA journal_mode = wal;
+} {1 {cannot change from wal2 to wal mode}}
+db close
+do_test 1.4.3 { hexio_read test.db 18 2 } 0303
+
+#-------------------------------------------------------------------------
+# Test that recovery in wal2 mode works.
+#
+forcedelete test.db test.db-wal test.db-wal2
+reset_db
+do_execsql_test 2.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 5000;
+} {wal2 5000}
+
+proc wal_hook {DB nm nFrame} { $DB eval { PRAGMA wal_checkpoint } }
+db wal_hook {wal_hook db}
+
+for {set i 1} {$i <= 200} {incr i} {
+  execsql { INSERT INTO t1 VALUES(NULL, randomblob(100)) }
+  set res [db eval { SELECT sum(a), md5sum(b) FROM t1 }]
+
+  do_test 2.1.$i {
+    foreach f [glob -nocomplain test.db2*] { forcedelete $f }
+    forcecopy test.db      test.db2
+    forcecopy test.db-wal  test.db2-wal
+    forcecopy test.db-wal2 test.db2-wal2
+
+    sqlite3 db2 test.db2
+    db2 eval { SELECT sum(a), md5sum(b) FROM t1 }
+  } $res
+
+  db2 close
+}
+
+#-------------------------------------------------------------------------
+
+reset_db
+do_execsql_test 3.0 {
+  CREATE TABLE t1(x BLOB, y INTEGER PRIMARY KEY);
+  CREATE INDEX i1 ON t1(x);
+  PRAGMA cache_size = 5;
+  PRAGMA journal_mode = wal2;
+} {wal2}
+
+do_test 3.1 {
+  execsql BEGIN
+  for {set i 1} {$i < 1000} {incr i} {
+    execsql { INSERT INTO t1 VALUES(randomblob(800), $i) }
+  }
+  execsql COMMIT
+} {}
+
+do_execsql_test 3.2 {
+  PRAGMA integrity_check;
+} {ok}
+
+#-------------------------------------------------------------------------
+catch { db close }
+foreach f [glob -nocomplain test.db*] { forcedelete $f }
+reset_db
+do_execsql_test 4.0 {
+  CREATE TABLE t1(x, y);
+  PRAGMA journal_mode = wal2;
+} {wal2}
+
+do_execsql_test 4.1 {
+  SELECT * FROM t1;
+} {}
+
+do_execsql_test 4.2 {
+  INSERT INTO t1 VALUES(1, 2);
+} {}
+
+do_execsql_test 4.3 {
+  SELECT * FROM t1;
+} {1 2}
+
+do_test 4.4 {
+  sqlite3 db2 test.db
+  execsql { SELECT * FROM t1 } db2
+} {1 2}
+
+do_test 4.5 {
+  lsort [glob test.db*]
+} {test.db test.db-shm test.db-wal test.db-wal2}
+
+do_test 4.6 {
+  db close
+  db2 close
+  sqlite3 db test.db
+  execsql { SELECT * FROM t1 }
+} {1 2}
+
+do_execsql_test 4.7 {
+  PRAGMA journal_size_limit = 4000;
+  INSERT INTO t1 VALUES(3, 4);
+  INSERT INTO t1 VALUES(5, 6);
+  INSERT INTO t1 VALUES(7, 8);
+  INSERT INTO t1 VALUES(9, 10);
+  INSERT INTO t1 VALUES(11, 12);
+  INSERT INTO t1 VALUES(13, 14);
+  INSERT INTO t1 VALUES(15, 16);
+  INSERT INTO t1 VALUES(17, 18);
+  SELECT * FROM t1;
+} {4000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18}
+
+do_test 4.8 {
+  sqlite3 db2 test.db
+  execsql { SELECT * FROM t1 } db2
+} {1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18}
+
+do_test 4.9 {
+  db close
+  db2 close
+  lsort [glob test.db*]
+} {test.db}
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 5.0 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c);
+  CREATE INDEX i1 ON t1(b, c);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 4000;
+} {wal2 4000}
+
+proc wal_hook {DB nm nFrame} {
+  $DB eval { PRAGMA wal_checkpoint }
+}
+db wal_hook [list wal_hook db]
+
+
+foreach js {4000 8000 12000} {
+  foreach NROW [list 100 200 300 400 500 600 1000] {
+    do_test 5.$js.$NROW.1 {
+      db eval "DELETE FROM t1"
+      db eval "PRAGMA journal_size_limit = $js"
+      set nTotal 0
+      for {set i 0} {$i < $NROW} {incr i} {
+        db eval { INSERT INTO t1 VALUES($i, $i, randomblob(abs(random()%50))) }
+        incr nTotal $i
+      }
+      set {} {}
+    } {}
+
+    do_test 5.$js.$NROW.2 {
+      sqlite3 db2 test.db
+      db2 eval { 
+        PRAGMA integrity_check;
+        SELECT count(*), sum(b) FROM t1;
+      }
+    } [list ok $NROW $nTotal]
+
+    db2 close
+  }
+}
+
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 6.0 {
+  CREATE TABLE tx(x);
+  PRAGMA journal_mode = wal2;
+  PRAGMA journal_size_limit = 3500;
+} {wal2 3500}
+
+do_test 6.1 {
+  for {set i 0} {$i < 10} {incr i} {
+    execsql "CREATE TABLE t$i (x);"
+  }
+} {}
+
+do_test 6.2.1 {
+  foreach f [glob -nocomplain test.db2*] { forcedelete $f }
+  forcecopy test.db-wal2 test.db2-wal2
+  sqlite3 db2 test.db2
+  db2 eval { SELECT * FROM sqlite_master }
+} {}
+do_test 6.2.2 {
+  db2 eval {
+    PRAGMA journal_mode = wal2;
+    SELECT * FROM sqlite_master;
+  }
+} {wal2}
+
+do_test 6.3.1 {
+  db2 close
+  foreach f [glob -nocomplain test.db2*] { forcedelete $f }
+  forcecopy test.db-wal2 test.db2-wal2
+  forcecopy test.db test.db2
+  sqlite3 db2 test.db2
+  db2 eval { SELECT * FROM sqlite_master }
+} {table tx tx 2 {CREATE TABLE tx(x)}}
+do_test 6.3.2 {
+  db2 eval {
+    PRAGMA journal_mode = wal2;
+    SELECT * FROM sqlite_master;
+  }
+} {wal2 table tx tx 2 {CREATE TABLE tx(x)}}
+
+do_test 6.4.1 {
+  db2 close
+  foreach f [glob -nocomplain test.db2*] { forcedelete $f }
+  forcecopy test.db-wal2 test.db2-wal2
+  forcecopy test.db-wal test.db2-wal
+  sqlite3 db2 test.db2
+  db2 eval { SELECT * FROM sqlite_master }
+} {}
+do_test 6.4.2 {
+  db2 eval {
+    PRAGMA journal_mode = wal2;
+    SELECT * FROM sqlite_master;
+  }
+} {wal2}
+db2 close
+
+#-------------------------------------------------------------------------
+reset_db
+sqlite3 db2 test.db
+do_execsql_test 7.0 {
+  PRAGMA journal_size_limit = 10000;
+  PRAGMA journal_mode = wal2;
+  PRAGMA wal_autocheckpoint = 0;
+  BEGIN;
+    CREATE TABLE t1(a);
+    INSERT INTO t1 VALUES( randomblob(8000) );
+  COMMIT;
+} {10000 wal2 0}
+
+do_test 7.1 {
+  list [file size test.db-wal] [file size test.db-wal2]
+} {9464 0}
+
+# Connection db2 is holding a PART1 lock. 
+#
+#   7.2.2: Test that the PART1 does not prevent db from switching to the
+#          other wal file.
+#
+#   7.2.3: Test that the PART1 does prevent a checkpoint of test.db-wal.
+#
+#   7.2.4: Test that after the PART1 is released the checkpoint is possible.
+#
+do_test 7.2.1 {
+  execsql {
+    BEGIN;
+      SELECT count(*) FROM t1;
+  } db2
+} {1}
+do_test 7.2.2 {
+  execsql {
+    INSERT INTO t1 VALUES( randomblob(800) );
+    INSERT INTO t1 VALUES( randomblob(800) );
+  }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {13656 3176 1024}
+do_test 7.2.3 {
+  execsql { PRAGMA wal_checkpoint }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {13656 3176 1024}
+do_test 7.2.4 {
+  execsql { END } db2
+  execsql { PRAGMA wal_checkpoint }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {13656 3176 11264}
+
+# Connection db2 is holding a PART2_FULL1 lock. 
+#
+#   7.3.2: Test that the lock does not prevent checkpointing.
+#
+#   7.3.3: Test that the lock does prevent the writer from overwriting 
+#          test.db-wal.
+#
+#   7.3.4: Test that after the PART2_FULL1 is released the writer can
+#          switch wal files and overwrite test.db-wal
+#
+db close
+db2 close
+sqlite3 db test.db
+sqlite3 db2 test.db
+do_test 7.3.1 {
+  execsql {
+    PRAGMA wal_autocheckpoint = 0;
+    PRAGMA journal_size_limit = 10000;
+    INSERT INTO t1 VALUES(randomblob(10000));
+    INSERT INTO t1 VALUES(randomblob(500));
+  }
+  execsql {
+    BEGIN;
+      SELECT count(*) FROM t1;
+  } db2
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 3176 12288}
+do_test 7.3.2 {
+  execsql { PRAGMA wal_checkpoint }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 3176 22528}
+do_test 7.3.3 {
+  execsql { 
+    INSERT INTO t1 VALUES(randomblob(10000));
+    INSERT INTO t1 VALUES(randomblob(500));
+  }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 18896 22528}
+do_test 7.3.4 {
+  execsql END db2
+  execsql { INSERT INTO t1 VALUES(randomblob(5000)); }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 18896 22528}
+
+# Connection db2 is holding a PART2 lock. 
+#
+#   7.4.2: Test that the lock does not prevent writer switching to test.db-wal.
+#
+#   7.3.3: Test that the lock does prevent checkpointing of test.db-wal2.
+#
+#   7.3.4: Test that after the PART2 is released test.db-wal2 can be
+#          checkpointed.
+#
+db close
+db2 close
+breakpoint
+sqlite3 db test.db
+sqlite3 db2 test.db
+do_test 7.4.1 {
+  execsql {
+    PRAGMA wal_autocheckpoint = 0;
+    PRAGMA journal_size_limit = 10000;
+    INSERT INTO t1 VALUES(randomblob(10000));
+    INSERT INTO t1 VALUES(randomblob(10000));
+    PRAGMA wal_checkpoint;
+  }
+  execsql {
+    BEGIN;
+      SELECT count(*) FROM t1;
+  } db2
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 12608 50176}
+do_test 7.4.2 {
+  execsql { 
+    INSERT INTO t1 VALUES(randomblob(5000));
+  }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 12608 50176}
+do_test 7.4.3 {
+  execsql { PRAGMA wal_checkpoint }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 12608 50176}
+do_test 7.4.4 {
+  execsql END db2
+  execsql { PRAGMA wal_checkpoint }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 12608 60416}
+
+# Connection db2 is holding a PART1_FULL2 lock. 
+#
+#   7.5.2: Test that the lock does not prevent a checkpoint of test.db-wal2.
+#
+#   7.5.3: Test that the lock does prevent the writer from overwriting
+#          test.db-wal2.
+#
+#   7.5.4: Test that after the PART1_FULL2 lock is released, the writer
+#          can switch to test.db-wal2.
+#
+db close
+db2 close
+sqlite3 db test.db
+sqlite3 db2 test.db
+do_test 7.5.1 {
+  execsql {
+    PRAGMA wal_autocheckpoint = 0;
+    PRAGMA journal_size_limit = 10000;
+    INSERT INTO t1 VALUES(randomblob(10000));
+    INSERT INTO t1 VALUES(randomblob(10000));
+    PRAGMA wal_checkpoint;
+    INSERT INTO t1 VALUES(randomblob(5000));
+  }
+  execsql {
+    BEGIN;
+      SELECT count(*) FROM t1;
+  } db2
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 12608 76800}
+do_test 7.5.2 {
+  execsql { PRAGMA wal_checkpoint }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {12608 12608 87040}
+do_test 7.5.3.1 {
+  execsql { INSERT INTO t1 VALUES(randomblob(5000)) }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {14704 12608 87040}
+do_test 7.5.3.2 {
+  execsql { INSERT INTO t1 VALUES(randomblob(5000)) }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {22040 12608 87040}
+do_test 7.5.4 {
+  execsql END db2
+  execsql { INSERT INTO t1 VALUES(randomblob(5000)) }
+  list [file size test.db-wal] [file size test.db-wal2] [file size test.db]
+} {22040 12608 87040}
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 8.0 {
+  PRAGMA journal_size_limit = 10000;
+  PRAGMA journal_mode = wal2;
+  CREATE TABLE t1(x);
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  BEGIN;
+    INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+} {10000 wal2}
+
+sqlite3 db2 test.db
+do_execsql_test -db db2 8.1 {
+  PRAGMA wal_checkpoint;
+} {0 50 13}
+
+do_execsql_test 8.2 {
+  COMMIT;
+}
+
+db2 close
+
+
+#-------------------------------------------------------------------------
+reset_db
+do_execsql_test 9.0 {
+  PRAGMA journal_size_limit = 10000;
+  PRAGMA journal_mode = wal2;
+  CREATE TABLE t1(x);
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+} {10000 wal2}
+
+do_execsql_test 9.1 {
+  PRAGMA wal_checkpoint;
+} {0 50 13}
+
+
+#-------------------------------------------------------------------------
+# Check that it is possible to do a non-PASSIVE checkpoint on a wal2
+# db without blocking writers.
+#
+reset_db
+do_execsql_test 10.0 {
+  PRAGMA journal_size_limit = 10000;
+  PRAGMA journal_mode = wal2;
+  CREATE TABLE t1(x);
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+  BEGIN;
+    INSERT INTO t1 VALUES( hex( randomblob(5000) ) );
+} {10000 wal2}
+
+sqlite3 db2 test.db
+do_execsql_test -db db2 10.1 {
+  PRAGMA wal_checkpoint = FULL;
+} {0 50 13}
+
+do_execsql_test 10.2 {
+  COMMIT;
+}
+
+finish_test
+
@@ -0,0 +1,93 @@
+# 2018 December 5
+#
+# The author disclaims copyright to this source code.  In place of
+# a legal notice, here is a blessing:
+#
+#    May you do good and not evil.
+#    May you find forgiveness for yourself and forgive others.
+#    May you share freely, never taking more than you give.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this file is testing the operation of the library in
+# "PRAGMA journal_mode=WAL2" mode.
+#
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+set testprefix wal2snapshot
+ifcapable !wal {finish_test ; return }
+ifcapable !snapshot {finish_test; return}
+
+foreach {tn mode} {1 wal 2 wal2} {
+  reset_db
+  do_execsql_test $tn.1 "PRAGMA journal_mode = $mode" $mode
+
+  do_execsql_test $tn.2 {
+    CREATE TABLE t1(a, b);
+    INSERT INTO t1 VALUES(1, 2);
+    INSERT INTO t1 VALUES(3, 4);
+    BEGIN;
+  }
+
+  # Check that sqlite3_snapshot_get() is an error for a wal2 db.
+  #
+  if {$tn==1} {
+    do_test 1.3 {
+      set S [sqlite3_snapshot_get db main]
+      sqlite3_snapshot_free $S
+    } {}
+  } else {
+    do_test 2.3 {
+      list [catch { sqlite3_snapshot_get db main } msg] $msg
+    } {1 SQLITE_ERROR}
+  }
+  
+  # Check that sqlite3_snapshot_recover() is an error for a wal2 db.
+  #
+  do_execsql_test $tn.4 COMMIT
+  if {$tn==1} {
+    do_test 1.5 {
+      sqlite3_snapshot_recover db main
+    } {}
+  } else {
+    do_test 2.5 {
+      list [catch { sqlite3_snapshot_recover db main } msg] $msg
+    } {1 SQLITE_ERROR}
+  }
+ 
+  # Check that sqlite3_snapshot_open() is an error for a wal2 db.
+  #
+  if {$tn==1} {
+    do_test 1.6 {
+      execsql BEGIN
+      set SNAPSHOT [sqlite3_snapshot_get_blob db main]
+      sqlite3_snapshot_open_blob db main $SNAPSHOT
+      execsql COMMIT
+    } {}
+  } else {
+    do_test 2.6.1 {
+      execsql BEGIN
+      set res [
+        list [catch { sqlite3_snapshot_open_blob db main $SNAPSHOT } msg] $msg
+      ]
+      execsql COMMIT
+      set res
+    } {1 SQLITE_ERROR}
+    do_test 2.6.2 {
+      execsql BEGIN
+      execsql {SELECT * FROM sqlite_master}
+      set res [
+        list [catch { sqlite3_snapshot_open_blob db main $SNAPSHOT } msg] $msg
+      ]
+      execsql COMMIT
+      set res
+    } {1 SQLITE_ERROR}
+  }
+}
+
+
+finish_test
+
+
@@ -85,7 +85,7 @@ proc lock_callback {method filename handle lock} {
    db2 eval { INSERT INTO x VALUES('x') }
  }
 }
-db timeout 10
+db timeout 1100
 do_catchsql_test 2.4 {
  BEGIN EXCLUSIVE;
 } {0 {}}
@@ -395,6 +395,8 @@ set options(THREADSAFE) {
 #endif
 }

+set options(WAL2) { "WAL2", }
+
 proc trim_name {in} {
  set ret $in
  if {[string range $in 0 6]=="SQLITE_"} {
@@ -83,19 +83,11 @@ int main(int argc, char const * const * argv){
    printf("{\"libVersion\": \"%s\", "
           "\"libVersionNumber\": %d, "
           "\"sourceId\": \"%s\","
-           "\"downloadVersion\": %d,"
-           "\"scm\":{ "
-           "\"sha3-256\": \"%s\","
-           "\"branch\": \"" SQLITE_SCM_BRANCH "\","
-           "\"tags\": \"" SQLITE_SCM_TAGS "\","
-           "\"datetime\": \"" SQLITE_SCM_DATETIME "\""
-           "}"
-           "}"/*missing newline is intentional*/,
+           "\"downloadVersion\": %d}"/*missing newline is intentional*/,
           SQLITE_VERSION,
           SQLITE_VERSION_NUMBER,
           SQLITE_SOURCE_ID,
-           dlVersion,
-           SQLITE_SOURCE_ID+20);
+           dlVersion);
  }else{
    if(fQuote) printf("%c", '"');
    if( fVersion ){