Trying to get the new AS MATERIALIZE syntax of CTEs to work. There are

still performance and memory management issues.  This is a WIP check-in.

FossilOrigin-Name: bf0fd9b23a77a8fc1be5f8f8f9f7dce62b924d2f4eecaf13f0b21cc58bfd3a61

manifest

@@ -1,5 +1,5 @@
-C Fix\san\sissue\swith\sthe\sLIKE\soperator\swhen\sit\sincludes\sthe\s"ESCAPE\s'_'"\sclause.\nTicket\s[c0aeea67d58ae0fd].
-D 2021-02-15T17:02:01.949
+C Trying\sto\sget\sthe\snew\sAS\sMATERIALIZE\ssyntax\sof\sCTEs\sto\swork.\s\sThere\sare\nstill\sperformance\sand\smemory\smanagement\sissues.\s\sThis\sis\sa\sWIP\scheck-in.
+D 2021-02-16T16:32:07.810
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -485,15 +485,15 @@ F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
 F src/btree.c 694020ad8a3af3d79b09f74c8f1421272a419cdea42a13401e3b0f7dea6e9c3e
 F src/btree.h 285f8377aa1353185a32bf455faafa9ff9a0d40d074d60509534d14990c7829e
 F src/btreeInt.h 7614cae30f95b6aed0c7cac7718276a55cfe2c77058cbfd8bef5b75329757331
-F src/build.c 1bae5588bfdf21bdf41e634f0a053d633fb1ae3a2896117b4eea76412b76c2e0
+F src/build.c 9d51da4a93227beb389ec6f6f97d4153ec59ffcbdf415f508de8fdf7ac48c0b9
 F src/callback.c d0b853dd413255d2e337b34545e54d888ea02f20da5ad0e63585b389624c4a6c
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 2a322b9a3d75771fb4d99e0702851f4f68dda982507a0f798eefb0712969a410
 F src/date.c dace306a10d9b02ee553d454c8e1cf8d3c9b932e137738a6b15b90253a9bfc10
 F src/dbpage.c 8a01e865bf8bc6d7b1844b4314443a6436c07c3efe1d488ed89e81719047833a
 F src/dbstat.c 3aa79fc3aed7ce906e4ea6c10e85d657299e304f6049861fe300053ac57de36c
-F src/delete.c 352ea931218c45a3daf17472d4141b9c7fc026d85da3f1ade404ea5bb6d67f77
-F src/expr.c 47c85263e6d179424e6b09e2c79db5704ab5b8cbc2fae2ee3285faa2566f2e74
+F src/delete.c 8517d4d57dc12e4cb9adec1801249ce18a3be3e6ccd75a266f66499a57e5b062
+F src/expr.c fe76d3b9f606347b1d84cb059264ed0ba0f33ecce57a864f1575bc3d8ae42ba9
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 73adaca988d0dd517d373b432dc9dfa2cd7fa3108b114260132a80832de19037
 F src/func.c 479f6929be027eb0210cbdde9d3529c012facf082d64a6b854a9415940761e5e
@@ -530,23 +530,23 @@ F src/os_win.c 77d39873836f1831a9b0b91894fec45ab0e9ca8e067dc8c549e1d1eca1566fe9
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c c49952ac5e9cc536778eff528091d79d38b3e45cbeeed4695dc05e207dc6547d
 F src/pager.h 4bf9b3213a4b2bebbced5eaa8b219cf25d4a82f385d093cd64b7e93e5285f66f
-F src/parse.y 67ba503780de64b967ae195b7e14c33531329228e1bc0b83d63324beb733680b
+F src/parse.y 7bec75e74a457d1569b093367924c897776375167b66b40c7464e8f63823fa21
 F src/pcache.c 385ff064bca69789d199a98e2169445dc16e4291fa807babd61d4890c3b34177
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c 6596e10baf3d8f84cc1585d226cf1ab26564a5f5caf85a15757a281ff977d51a
 F src/pragma.c 6daaaecc26a4b09481d21722525b079ce756751a43a79cc1d8f122d686806193
 F src/pragma.h 8dc78ab7e9ec6ce3ded8332810a2066f1ef6267e2e03cd7356ee00276125c6cf
-F src/prepare.c f288cbc35f79eb32e162de7e80a63ebe00d80e639dcfac071bee11570cbdb16f
+F src/prepare.c e8e056d7e34e5b1092a0f0d4f537278175c806412f8fa605b5f50a40ca0915d3
 F src/printf.c 30e92b638fac71dcd85cdea1d12ecfae354c9adee2c71e8e1ae4727cde7c91ed
 F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
 F src/resolve.c 89e4faf6171e179edf279905e8e45c4f9dd108777dc60716396729fbd7cb045e
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
-F src/select.c 9b4c84fd2703ee3c8b5d4b189387482a84c26acf2c38ca4835db5b48c68a09d4
+F src/select.c 847bdf40d4b3b04f3316b3ead543ef49596f4f53e48f810c60ce9649748b2774
 F src/shell.c.in 9ebc74e4f05cfbd0f4a36060fdaeff1da4e9af4458358722bc08c5a1ab9a0879
 F src/sqlite.h.in 8855a19f37ade8dad189a9e48233a2ebe1b46faf469c7eb0906a654e252dcc57
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 61b38c073d5e1e96a3d45271b257aef27d0d13da2bea5347692ae579475cd95e
-F src/sqliteInt.h 4cb469678a0dbf814e4efbde4488a0161a5398e9a63141830d9f676b4e9fb0cc
+F src/sqliteInt.h d0f3ca58ec5cf148210b186d9eddbb32e847cc845b887506a759d9c255cf0319
 F src/sqliteLimit.h d7323ffea5208c6af2734574bae933ca8ed2ab728083caa117c9738581a31657
 F src/status.c 4b8bc2a6905163a38b739854a35b826c737333fab5b1f8e03fa7eb9a4799c4c1
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -628,7 +628,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 69e770e96fd56cc21608992bf2c6f1f3dc5cf2572d0495c6a643b06c3a679f14
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c d9c4e454ebb9499e908aa62d55b8994c375cf5355ac78f60d45af17f7890701c
-F src/where.c 6efc4a10bfe0ec908c4f3c9112afb7675c952204b4b0b255672f488860141fec
+F src/where.c 228cb57b51ca02853bb932c4548ffaa3949f40f8398a0f393683dd4c08cdbea0
 F src/whereInt.h ae03b5e3a4cca9bd9cb1b7d3c63faf8f1f177200fc8cecc87d3d0cab6ca338e6
 F src/wherecode.c 43a63441f8662ddf86b15975683a502ec33f08167e9636f4d19e38e265e95fd9
 F src/whereexpr.c f7b5469e83db3c3b9eb14e4ba44559a2e125523761d12e5ac8d8fb88301af393
@@ -1828,7 +1828,7 @@ F tool/max-limits.c cbb635fbb37ae4d05f240bfb5b5270bb63c54439
 F tool/mkautoconfamal.sh f62353eb6c06ab264da027fd4507d09914433dbdcab9cb011cdc18016f1ab3b8
 F tool/mkccode.tcl 86463e68ce9c15d3041610fedd285ce32a5cf7a58fc88b3202b8b76837650dbe x
 F tool/mkctimec.tcl dd183b73ae1c28249669741c250525f0407e579a70482371668fd5f130d9feb3
-F tool/mkkeywordhash.c 750f25aef0e23f8e3367af6d824fbf5ed7d3e285f27cea91aa2dd72c367630eb
+F tool/mkkeywordhash.c 08b6e4d7a482a7f37a9a0032e7ba968e26624a027b6b2e9ba589be6f5e3d8c2c
 F tool/mkmsvcmin.tcl 6ecab9fe22c2c8de4d82d4c46797bda3d2deac8e763885f5a38d0c44a895ab33
 F tool/mkopcodec.tcl d1b6362bd3aa80d5520d4d6f3765badf01f6c43c
 F tool/mkopcodeh.tcl 352a4319c0ad869eb26442bf7c3b015aa15594c21f1cce5a6420dbe999367c21
@@ -1900,7 +1900,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 7cc65ae57183b3c16f1102fca5603a36acda432e5d45e22a2996e5ebe069fc6a
-R 3ed1929e1ca13bbf9ff7ef7c6dc85f4d
+P 78dcddd9697d95629c18131ab0842aa4d08bc3c7451cd0e7a8d83e4dde277bda
+R 3e33372448628596b79c8e4959bb7ced
+T *branch * using-materialize
+T *sym-using-materialize *
+T -sym-with-generated-as *
 U drh
-Z b9fb1ccb5459387ee6a14bca5dee2b45
+Z 4d1724c077b98d0e6366cdc6b7fd4796

manifest.uuid

@@ -1 +1 @@
-27d4117980d125975b5e70eeea58a6ab07bcf066e71b5fcb81b822e05afdbab0
+bf0fd9b23a77a8fc1be5f8f8f9f7dce62b924d2f4eecaf13f0b21cc58bfd3a61

src/build.c

@@ -5204,24 +5204,112 @@ KeyInfo *sqlite3KeyInfoOfIndex(Parse *pParse, Index *pIdx){
 }
 
 #ifndef SQLITE_OMIT_CTE
+/*
+** Create a new CTE object
+*/
+Cte *sqlite3CteNew(
+  Parse *pParse,          /* Parsing context */
+  Token *pName,           /* Name of the common-table */
+  ExprList *pArglist,     /* Optional column name list for the table */
+  Select *pQuery,         /* Query used to initialize the table */
+  int eMaterialize        /* Force or prohibit materialization */
+){
+  Cte *pNew;
+  sqlite3 *db = pParse->db;
+
+  assert( eMaterialize==Materialize_Any
+       || eMaterialize==Materialize_Yes
+       || eMaterialize==Materialize_No );
+  pNew = sqlite3DbMallocZero(db, sizeof(*pNew));
+  assert( pNew!=0 || db->mallocFailed );
+
+  if( db->mallocFailed ){
+    sqlite3ExprListDelete(db, pArglist);
+    sqlite3SelectDelete(db, pQuery);
+  }else{
+    pNew->pSelect = pQuery;
+    pNew->pCols = pArglist;
+    pNew->zName = sqlite3NameFromToken(pParse->db, pName);
+    pNew->zCteErr = 0;
+    pNew->eMaterialize = (u8)eMaterialize;
+  }
+  return pNew;
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** Validate the back-reference from a SrcList_item back to its Cte object.
+** Raise an assertion fault if anything is wrong.  This routine is for
+** sanity and design checking and does not appear in release builds.
+*/
+void sqlite3AssertValidCteBackRef(struct SrcList_item *pItem){
+  Cte *pCte;
+  if( !pItem->fg.isCte ) return;   /* Nothing to check here */
+  assert( pItem->pSelect!=0 );
+  pCte = pItem->u2.pCteSrc;
+  if( pCte==0 ) return;
+  assert( pCte->eCteMagic==CTE_MAGIC );
+  assert( pItem->pTab!=0 );
+  assert( sqlite3_stricmp(pCte->zName, pItem->pTab->zName)==0 );
+  assert( pCte->nRefCte>=1 );
+}
+#endif /* SQLITE_DEBUG */
+
+/*
+** Clear information from a Cte object, but do not deallocate storage.
+*/
+static void cteClear(sqlite3 *db, Cte *pCte){
+  sqlite3ExprListDelete(db, pCte->pCols);
+  sqlite3SelectDelete(db, pCte->pSelect);
+  sqlite3DbFree(db, pCte->zName);
+#ifdef SQLITE_DEBUG
+  if( db==0 || db->pnBytesFreed==0 ){
+    pCte->zName = 0;
+    pCte->eCteMagic = 0;
+  }
+#endif
+}
+
+/*
+** Free the contents of the CTE object passed as the second argument.
+*/
+void sqlite3CteDelete(sqlite3 *db, Cte *pCte){
+  if( pCte ){
+    cteClear(db, pCte);
+    sqlite3DbFree(db, pCte);
+  }
+}
+
 /* 
 ** This routine is invoked once per CTE by the parser while parsing a 
-** WITH clause. 
+** WITH clause.   Construct a new Cte object and append it to the
+** input With object, reallocating the With object as needed.  If the
+** pWith input is NULL, then create a new With object.
+**
+** The returned With object is unowned.  The caller needs to assign
+** ownership.  Note, however, that ownership should not be assigned
+** until the object stops growing.  The input pWith parameter must be
+** either NULL or a pointer to an unowned With object.
 */
 With *sqlite3WithAdd(
   Parse *pParse,          /* Parsing context */
   With *pWith,            /* Existing WITH clause, or NULL */
-  Token *pName,           /* Name of the common-table */
-  ExprList *pArglist,     /* Optional column name list for the table */
-  Select *pQuery          /* Query used to initialize the table */
+  Cte *pCte               /* The CTE to add to the WITH clause */
 ){
   sqlite3 *db = pParse->db;
   With *pNew;
   char *zName;
 
+  /* The input WITH clause is yet unowned */
+  assert( pWith==0 || pWith->mOwner==0 );
+
+  if( pCte==0 ){
+    return pWith;
+  }
+
   /* Check that the CTE name is unique within this WITH clause. If
   ** not, store an error in the Parse structure. */
-  zName = sqlite3NameFromToken(pParse->db, pName);
+  zName = pCte->zName;
   if( zName && pWith ){
     int i;
     for(i=0; i<pWith->nCte; i++){
@@ -5237,37 +5325,76 @@ With *sqlite3WithAdd(
   }else{
     pNew = sqlite3DbMallocZero(db, sizeof(*pWith));
   }
-  assert( (pNew!=0 && zName!=0) || db->mallocFailed );
 
   if( db->mallocFailed ){
-    sqlite3ExprListDelete(db, pArglist);
-    sqlite3SelectDelete(db, pQuery);
-    sqlite3DbFree(db, zName);
+    sqlite3CteDelete(db, pCte);
     pNew = pWith;
   }else{
-    pNew->a[pNew->nCte].pSelect = pQuery;
-    pNew->a[pNew->nCte].pCols = pArglist;
-    pNew->a[pNew->nCte].zName = zName;
-    pNew->a[pNew->nCte].zCteErr = 0;
+    pNew->a[pNew->nCte] = *pCte;
+    sqlite3DbFree(db, pCte);
     pNew->nCte++;
   }
-
   return pNew;
 }
 
 /*
 ** Free the contents of the With object passed as the second argument.
+**
+** The sqlite3WithReleaseBySelect() causes the Select-object ownership
+** to be released, and sqlite3WithReleaseByParse() causes the Parse-object
+** ownership to be released.  The With object is only deallocated after
+** both owners release it. 
 */
 void sqlite3WithDelete(sqlite3 *db, With *pWith){
-  if( pWith ){
-    int i;
-    for(i=0; i<pWith->nCte; i++){
-      struct Cte *pCte = &pWith->a[i];
-      sqlite3ExprListDelete(db, pCte->pCols);
-      sqlite3SelectDelete(db, pCte->pSelect);
-      sqlite3DbFree(db, pCte->zName);
-    }
-    sqlite3DbFree(db, pWith);
+  int i;
+  for(i=0; i<pWith->nCte; i++){
+    cteClear(db, &pWith->a[i]);
+  }
+  sqlite3DbFree(db, pWith);
+}
+void sqlite3WithReleaseBySelect(sqlite3 *db, With *pWith){
+  if( pWith==0 ) return;
+  if( db && db->pnBytesFreed ){
+    if( pWith->mOwner==WithOwnedBySelect ) sqlite3WithDelete(db, pWith);
+  }else{
+    pWith->mOwner &= ~WithOwnedBySelect;
+    if( pWith->mOwner==0 ) sqlite3WithDelete(db, pWith);
   }
 }
+void sqlite3WithReleaseByParse(sqlite3 *db, With *pWith){
+  if( pWith==0 ) return;
+  if( db && db->pnBytesFreed ){
+    sqlite3WithDelete(db, pWith);
+  }else{
+    pWith->mOwner &= ~WithOwnedByParse;
+    if( pWith->mOwner==0 ) sqlite3WithDelete(db, pWith);
+  }
+}
+
+/*
+** Add Select-object or Parse-object ownership to a With object.  If
+** the With object is already owned appropriately, then these routines
+** are no-ops.
+**
+** The first time that a With becomes owned by a Parse-object, make
+** arrangements to automatically release the ownership when the Parse
+** object is destroyed using a call to sqlite3ParserAddCleanup().
+** This involves a memory allocation.  If that memory allocation fails,
+** the With object might be destroyed immediately.  In that
+** case, return a NULL pointer. But usually, return a copy of the pWith
+** pointer.
+*/
+void sqlite3WithClaimedBySelect(With *pWith){
+  pWith->mOwner |= WithOwnedBySelect;
+}
+With *sqlite3WithClaimedByParse(Parse *pParse, With *pWith){
+  if( (pWith->mOwner & WithOwnedByParse)==0 ){
+    pWith->mOwner |= WithOwnedByParse;
+    pWith = (With*)sqlite3ParserAddCleanup(pParse,
+                     (void(*)(sqlite3*,void*))sqlite3WithReleaseByParse,
+                     (void*)pWith);
+  }
+  return pWith;
+}
+   
 #endif /* !defined(SQLITE_OMIT_CTE) */

src/delete.c

@@ -209,7 +209,7 @@ Expr *sqlite3LimitWhere(
   pSrc->a[0].pTab = 0;
   pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
   pSrc->a[0].pTab = pTab;
-  pSrc->a[0].pIBIndex = 0;
+  pSrc->a[0].u2.pIBIndex = 0; assert( !pSrc->a[0].fg.isCte );
 
   /* generate the SELECT expression tree. */
   pSelect = sqlite3SelectNew(pParse, pEList, pSelectSrc, pWhere, 0 ,0, 

src/expr.c

@@ -1401,6 +1401,7 @@ static With *withDup(sqlite3 *db, With *p){
     if( pRet ){
       int i;
       pRet->nCte = p->nCte;
+      pRet->mOwner = WithOwnedBySelect;
       for(i=0; i<p->nCte; i++){
         pRet->a[i].pSelect = sqlite3SelectDup(db, p->a[i].pSelect, 0);
         pRet->a[i].pCols = sqlite3ExprListDup(db, p->a[i].pCols, 0);
@@ -1544,7 +1545,7 @@ SrcList *sqlite3SrcListDup(sqlite3 *db, SrcList *p, int flags){
     if( pNewItem->fg.isIndexedBy ){
       pNewItem->u1.zIndexedBy = sqlite3DbStrDup(db, pOldItem->u1.zIndexedBy);
     }
-    pNewItem->pIBIndex = pOldItem->pIBIndex;
+    pNewItem->u2 = pOldItem->u2;
     if( pNewItem->fg.isTabFunc ){
       pNewItem->u1.pFuncArg = 
           sqlite3ExprListDup(db, pOldItem->u1.pFuncArg, flags);

src/parse.y

@@ -249,6 +249,9 @@ columnname(A) ::= nm(A) typetoken(Y). {sqlite3AddColumn(pParse,&A,&Y);}
 %endif SQLITE_OMIT_WINDOWFUNC
 %ifndef SQLITE_OMIT_GENERATED_COLUMNS
   GENERATED ALWAYS
+%endif
+%ifndef SQLITE_OMIT_CTE
+  MATERIALIZED
 %endif
   REINDEX RENAME CTIME_KW IF
   .
@@ -510,29 +513,29 @@ cmd ::= select(X).  {
       }
     }
   }
-}
+#ifndef SQLITE_OMIT_CTE
+  /* Link a With object to a Select object.
+  ** Both Select- and Parse-ownership is assigned to the With object
+  */
+  static Select *linkWithToSelect(Parse *pParse, Select *pSelect, With *pWith){
+    assert( pWith->mOwner==0 );
+    if( pSelect ){
+      pSelect->pWith = pWith;
+      sqlite3WithClaimedBySelect(pWith);
+      parserDoubleLinkSelect(pParse, pSelect);
+    }else{
+      sqlite3WithClaimedByParse(pParse,pWith);
+    }
+    return pSelect;
+  }
+#endif /* SQLITE_OMIT_CTE */
+} // end %include
+
 
 %ifndef SQLITE_OMIT_CTE
-select(A) ::= WITH wqlist(W) selectnowith(X). {
-  Select *p = X;
-  if( p ){
-    p->pWith = W;
-    parserDoubleLinkSelect(pParse, p);
-  }else{
-    sqlite3WithDelete(pParse->db, W);
-  }
-  A = p;
-}
-select(A) ::= WITH RECURSIVE wqlist(W) selectnowith(X). {
-  Select *p = X;
-  if( p ){
-    p->pWith = W;
-    parserDoubleLinkSelect(pParse, p);
-  }else{
-    sqlite3WithDelete(pParse->db, W);
-  }
-  A = p;
-}
+select(A) ::= WITH wqlist(W) selectnowith(X). { A = linkWithToSelect(pParse,X,W); }
+select(A) ::= WITH RECURSIVE wqlist(W) selectnowith(X).
+                                              { A = linkWithToSelect(pParse,X,W); }
 %endif /* SQLITE_OMIT_CTE */
 select(A) ::= selectnowith(X). {
   Select *p = X;
@@ -1657,18 +1660,27 @@ anylist ::= anylist ANY.
 
 //////////////////////// COMMON TABLE EXPRESSIONS ////////////////////////////
 %type wqlist {With*}
-%destructor wqlist {sqlite3WithDelete(pParse->db, $$);}
+%destructor wqlist {if($$)sqlite3WithDelete(pParse->db, $$);}
+%type wqitem {Cte*}
+%destructor wqitem {sqlite3CteDelete(pParse->db, $$);}
+%type wqas {int}
 
 with ::= .
 %ifndef SQLITE_OMIT_CTE
-with ::= WITH wqlist(W).              { sqlite3WithPush(pParse, W, 1); }
-with ::= WITH RECURSIVE wqlist(W).    { sqlite3WithPush(pParse, W, 1); }
+with ::= WITH wqlist(W).              { sqlite3WithPush(pParse, W); }
+with ::= WITH RECURSIVE wqlist(W).    { sqlite3WithPush(pParse, W); }
 
-wqlist(A) ::= nm(X) eidlist_opt(Y) AS LP select(Z) RP. {
-  A = sqlite3WithAdd(pParse, 0, &X, Y, Z); /*A-overwrites-X*/
+wqas(A) ::= AS.                   {A = Materialize_Any;}
+wqas(A) ::= AS MATERIALIZED.      {A = Materialize_Yes;}
+wqas(A) ::= AS NOT MATERIALIZED.  {A = Materialize_No;}
+wqitem(A) ::= nm(X) eidlist_opt(Y) wqas(F) LP select(Z) RP. {
+  A = sqlite3CteNew(pParse, &X, Y, Z, F); /*A-overwrites-X*/
 }
-wqlist(A) ::= wqlist(A) COMMA nm(X) eidlist_opt(Y) AS LP select(Z) RP. {
-  A = sqlite3WithAdd(pParse, A, &X, Y, Z);
+wqlist(A) ::= wqitem(X). {
+  A = sqlite3WithAdd(pParse, 0, X); /*A-overwrites-X*/
+}
+wqlist(A) ::= wqlist(A) COMMA wqitem(X). {
+  A = sqlite3WithAdd(pParse, A, X);
 }
 %endif  SQLITE_OMIT_CTE
 

src/prepare.c

@@ -608,7 +608,7 @@ void sqlite3ParserReset(Parse *pParse){
 **
 **       testcase( pParse->earlyCleanup );
 */
-void sqlite3ParserAddCleanup(
+void *sqlite3ParserAddCleanup(
   Parse *pParse,                      /* Destroy when this Parser finishes */
   void (*xCleanup)(sqlite3*,void*),   /* The cleanup routine */
   void *pPtr                          /* Pointer to object to be cleaned up */
@@ -621,10 +621,12 @@ void sqlite3ParserAddCleanup(
     pCleanup->xCleanup = xCleanup;
   }else{
     xCleanup(pParse->db, pPtr);
+    pPtr = 0;
 #if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
     pParse->earlyCleanup = 1;
 #endif
   }
+  return pPtr;
 }
 
 /*

src/select.c

@@ -90,7 +90,7 @@ static void clearSelect(sqlite3 *db, Select *p, int bFree){
       sqlite3WindowListDelete(db, p->pWinDefn);
     }
 #endif
-    if( OK_IF_ALWAYS_TRUE(p->pWith) ) sqlite3WithDelete(db, p->pWith);
+    if( p->pWith ) sqlite3WithReleaseBySelect(db, p->pWith);
     if( bFree ) sqlite3DbFreeNN(db, p);
     p = pPrior;
     bFree = 1;
@@ -4723,7 +4723,9 @@ int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
       pParse->checkSchema = 1;
       return SQLITE_ERROR;
     }
-    pFrom->pIBIndex = pIdx;
+    assert( pFrom->fg.isCte==0 );
+    assert( pFrom->pSelect==0 );
+    pFrom->u2.pIBIndex = pIdx;
   }
   return SQLITE_OK;
 }
@@ -4855,25 +4857,13 @@ static struct Cte *searchWith(
 
 /* The code generator maintains a stack of active WITH clauses
 ** with the inner-most WITH clause being at the top of the stack.
-**
-** This routine pushes the WITH clause passed as the second argument
-** onto the top of the stack. If argument bFree is true, then this
-** WITH clause will never be popped from the stack. In this case it
-** should be freed along with the Parse object. In other cases, when
-** bFree==0, the With object will be freed along with the SELECT 
-** statement with which it is associated.
 */
-void sqlite3WithPush(Parse *pParse, With *pWith, u8 bFree){
+void sqlite3WithPush(Parse *pParse, With *pWith){
   if( pWith ){
     assert( pParse->pWith!=pWith );
     pWith->pOuter = pParse->pWith;
     pParse->pWith = pWith;
-    if( bFree ){
-      sqlite3ParserAddCleanup(pParse, 
-         (void(*)(sqlite3*,void*))sqlite3WithDelete,
-         pWith);
-      testcase( pParse->earlyCleanup );
-    }
+    sqlite3WithClaimedByParse(pParse, pWith);
   }
 }
 
@@ -4938,6 +4928,17 @@ static int withExpand(
     pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0);
     if( db->mallocFailed ) return SQLITE_NOMEM_BKPT;
     assert( pFrom->pSelect );
+    if( pCte->eMaterialize==Materialize_Yes ){
+      pFrom->pSelect->selFlags |= SF_OptBarrier;
+    }
+    assert( !pFrom->fg.isIndexedBy );
+    pFrom->fg.isCte = 1;
+    assert( (pCte->eCteMagic==0 && pCte->nRefCte==0)
+         || (pCte->eCteMagic==CTE_MAGIC && pCte->nRefCte>0) );
+    pFrom->u2.pCteSrc = pCte;
+    sqlite3WithClaimedByParse(pParse, pWith);
+    pCte->nRefCte++;
+    VVA_ONLY( pCte->eCteMagic = CTE_MAGIC );
 
     /* Check if this is a recursive CTE. */
     pRecTerm = pSel = pFrom->pSelect;
@@ -5118,7 +5119,7 @@ static int selectExpander(Walker *pWalker, Select *p){
   }
   pTabList = p->pSrc;
   pEList = p->pEList;
-  sqlite3WithPush(pParse, p->pWith, 0);
+  sqlite3WithPush(pParse, p->pWith);
 
   /* Make sure cursor numbers have been assigned to all entries in
   ** the FROM clause of the SELECT statement.
@@ -5757,9 +5758,10 @@ static void havingToWhere(Parse *pParse, Select *p){
 }
 
 /*
-** Check to see if the pThis entry of pTabList is a self-join of a prior view.
-** If it is, then return the SrcList_item for the prior view.  If it is not,
-** then return 0.
+** Check to see if the pThis entry of pTabList is a self-join of a prior view,
+** or any reuse of a CTE that is not necessarily a self-join.
+** If it is, then return the SrcList_item for the prior view or CTE.
+** If it is not, then return 0.
 */
 static struct SrcList_item *isSelfJoinView(
   SrcList *pTabList,           /* Search for self-joins in this FROM clause */
@@ -5768,6 +5770,11 @@ static struct SrcList_item *isSelfJoinView(
   struct SrcList_item *pItem;
   assert( pThis->pSelect!=0 );
   if( pThis->pSelect->selFlags & SF_PushDown ) return 0;
+  if( pThis->fg.isCte ){
+    Cte *pCte = pThis->u2.pCteSrc;
+    sqlite3AssertValidCteBackRef(pThis);
+    return pCte->pCteMat;
+  }
   for(pItem = pTabList->a; pItem<pThis; pItem++){
     Select *pS1;
     if( pItem->pSelect==0 ) continue;
@@ -6070,6 +6077,9 @@ int sqlite3Select(
       continue;
     }
 
+    /* Do not flatten across an optimization barrier */
+    if( pSub->selFlags & SF_OptBarrier ) continue;
+
     if( flattenSubquery(pParse, p, i, isAgg) ){
       if( pParse->nErr ) goto select_end;
       /* This subquery can be absorbed into its parent. */
@@ -6135,6 +6145,7 @@ int sqlite3Select(
   */
   for(i=0; i<pTabList->nSrc; i++){
     struct SrcList_item *pItem = &pTabList->a[i];
+    struct SrcList_item *pPrior;
     SelectDest dest;
     Select *pSub;
 #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
@@ -6194,6 +6205,7 @@ int sqlite3Select(
     ** inside the subquery.  This can help the subquery to run more efficiently.
     */
     if( OptimizationEnabled(db, SQLITE_PushDown)
+     && (pSub->selFlags & SF_OptBarrier)==0
      && pushDownWhereTerms(pParse, pSub, p->pWhere, pItem->iCursor,
                            (pItem->fg.jointype & JT_OUTER)!=0)
     ){
@@ -6212,18 +6224,27 @@ int sqlite3Select(
     zSavedAuthContext = pParse->zAuthContext;
     pParse->zAuthContext = pItem->zName;
 
+    /* Verify that the CTE back-reference information is valid */
+    sqlite3AssertValidCteBackRef(pItem);
+
     /* Generate code to implement the subquery
     **
-    ** The subquery is implemented as a co-routine if the subquery is
+    ** The subquery is implemented as a co-routine if (1) the subquery is
     ** guaranteed to be the outer loop (so that it does not need to be
-    ** computed more than once)
+    ** computed more than once) and if (2) the subquery is a CTE that is
+    ** used only this one time.
     **
-    ** TODO: Are there other reasons beside (1) to use a co-routine
+    ** TODO: Are there other reasons beside (1) and (2) to use a co-routine
     ** implementation?
+    **
+    ** TODO: We might should allow a subquery that is an optimization barrier
+    ** to be implemented as a co-routine as long as we know that it is the
+    ** only use of the subquery.
     */
     if( i==0
      && (pTabList->nSrc==1
             || (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0)  /* (1) */
+     && (pItem->fg.isCte && pItem->u2.pCteSrc->nRefCte==1)          /* (2) */
     ){
       /* Implement a co-routine that will return a single row of the result
       ** set on each invocation.
@@ -6243,16 +6264,20 @@ int sqlite3Select(
       sqlite3VdbeEndCoroutine(v, pItem->regReturn);
       sqlite3VdbeJumpHere(v, addrTop-1);
       sqlite3ClearTempRegCache(pParse);
+    }else if( (pPrior = isSelfJoinView(pTabList,pItem))!=0 ){
+      /* This view has been previously materialized.  Use the
+      ** prior materialization */
+      if( pPrior->addrFillSub ){
+        sqlite3VdbeAddOp2(v, OP_Gosub, pPrior->regReturn, pPrior->addrFillSub);
+      }
+      sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
+      assert( pPrior->pSelect!=0 );
+      pSub->nSelectRow = pPrior->pSelect->nSelectRow;
     }else{
-      /* Generate a subroutine that will fill an ephemeral table with
-      ** the content of this subquery.  pItem->addrFillSub will point
-      ** to the address of the generated subroutine.  pItem->regReturn
-      ** is a register allocated to hold the subroutine return address
-      */
+      /* Materialize the view */
       int topAddr;
       int onceAddr = 0;
       int retAddr;
-      struct SrcList_item *pPrior;
 
       testcase( pItem->addrFillSub==0 ); /* Ticket c52b09c7f38903b1311 */
       pItem->regReturn = ++pParse->nMem;
@@ -6267,15 +6292,12 @@ int sqlite3Select(
       }else{
         VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName));
       }
-      pPrior = isSelfJoinView(pTabList, pItem);
-      if( pPrior ){
-        sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
-        assert( pPrior->pSelect!=0 );
-        pSub->nSelectRow = pPrior->pSelect->nSelectRow;
-      }else{
-        sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
-        ExplainQueryPlan((pParse, 1, "MATERIALIZE %u", pSub->selId));
-        sqlite3Select(pParse, pSub, &dest);
+      sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
+      ExplainQueryPlan((pParse, 1, "MATERIALIZE %u", pSub->selId));
+      sqlite3Select(pParse, pSub, &dest);
+      if( pItem->fg.isCte ){
+        sqlite3AssertValidCteBackRef(pItem);
+        pItem->u2.pCteSrc->pCteMat = pItem;
       }
       pItem->pTab->nRowLogEst = pSub->nSelectRow;
       if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);

src/sqliteInt.h

@@ -1136,6 +1136,7 @@ typedef struct AutoincInfo AutoincInfo;
 typedef struct Bitvec Bitvec;
 typedef struct CollSeq CollSeq;
 typedef struct Column Column;
+typedef struct Cte Cte;
 typedef struct Db Db;
 typedef struct DbFixer DbFixer;
 typedef struct Schema Schema;
@@ -2951,6 +2952,7 @@ struct SrcList {
       unsigned viaCoroutine :1;  /* Implemented as a co-routine */
       unsigned isRecursive :1;   /* True for recursive reference in WITH */
       unsigned fromDDL :1;       /* Comes from sqlite_schema */
+      unsigned isCte :1;         /* True if table is a CTE */
     } fg;
     int iCursor;      /* The VDBE cursor number used to access this table */
     Expr *pOn;        /* The ON clause of a join */
@@ -2960,7 +2962,10 @@ struct SrcList {
       char *zIndexedBy;    /* Identifier from "INDEXED BY <zIndex>" clause */
       ExprList *pFuncArg;  /* Arguments to table-valued-function */
     } u1;
-    Index *pIBIndex;  /* Index structure corresponding to u1.zIndexedBy */
+    union {
+      Index *pIBIndex;  /* Index structure corresponding to u1.zIndexedBy */
+      Cte *pCteSrc;     /* The original CTE, if fg.isCte is true */
+    } u2;
   } a[1];             /* One entry for each identifier on the list */
 };
 
@@ -3185,6 +3190,7 @@ struct Select {
 #define SF_NoopOrderBy   0x0400000 /* ORDER BY is ignored for this query */
 #define SF_UpdateFrom    0x0800000 /* Statement is an UPDATE...FROM */
 #define SF_PushDown      0x1000000 /* SELECT has be modified by push-down opt */
+#define SF_OptBarrier    0x2000000 /* SELECT is an optimization barrier */
 
 /*
 ** The results of a SELECT can be distributed in several ways, as defined
@@ -3867,20 +3873,55 @@ void sqlite3SelectWalkAssert2(Walker*, Select*);
 #define WRC_Prune       1   /* Omit children but continue walking siblings */
 #define WRC_Abort       2   /* Abandon the tree walk */
 
+/*
+** Allowed values for Cte.eMaterialize
+*/
+#define Materialize_Any   0   /* Not specified */
+#define Materialize_Yes   1   /* AS MATERIALIZED ... */
+#define Materialize_No    2   /* AS NOT MATERIALIZED.  Not currently used */
+
 /*
 ** An instance of this structure represents a set of one or more CTEs
 ** (common table expressions) created by a single WITH clause.
+**
+** A With object describes an entire WITH clause, which is composed of
+** one or more Cte objects.  During parsing, the Cte objects are created
+** separately for each common-table-expression, then copied into the
+** With object container.
+**
+** DUAL OWNERSHIP
+** The With object can be owned by a Select object (via the Select.pWith
+** field), or it can be owned by the Parse object of the current parse,
+** or by both.  The With.mOwner bitmask determines who owns each With object.
+** The object is not deallocated until all owners have released it.
 */
-struct With {
-  int nCte;                       /* Number of CTEs in the WITH clause */
-  With *pOuter;                   /* Containing WITH clause, or NULL */
-  struct Cte {                    /* For each CTE in the WITH clause.... */
-    char *zName;                    /* Name of this CTE */
-    ExprList *pCols;                /* List of explicit column names, or NULL */
-    Select *pSelect;                /* The definition of this CTE */
-    const char *zCteErr;            /* Error message for circular references */
-  } a[1];
+struct Cte {
+  char *zName;                  /* Name of this CTE */
+  ExprList *pCols;              /* List of explicit column names, or NULL */
+  Select *pSelect;              /* The definition of this CTE */
+  const char *zCteErr;          /* Error message for circular references */
+  u8 eMaterialize;              /* One of the Materialize_* options */
+  u16 eCteMagic;                /* Magic number for sanity checking */
+  u32 nRefCte;                  /* Number of times used */
+  struct SrcList_item *pCteMat; /* The materialization of this CTE */
 };
+struct With {
+  int nCte;                     /* Number of CTEs in the WITH clause */
+  int mOwner;                   /* Mask of bits to discribe ownership */
+  With *pOuter;                 /* Containing WITH clause, or NULL */
+  Cte a[1];                     /* The CTEs of this WITH clause */
+};
+
+/*
+** The correct value for Cte.eCteMagic if the Cte object is valid
+*/
+#define CTE_MAGIC  0x3f96  /* Magic number for valid Cte objects */
+
+/*
+** Ownership flags for With.
+*/
+#define WithOwnedBySelect 0x01  /* Owned by a Select object */
+#define WithOwnedByParse  0x10  /* Owned by the Parse object */
 
 #ifdef SQLITE_DEBUG
 /*
@@ -4868,7 +4909,7 @@ sqlite3_int64 sqlite3StmtCurrentTime(sqlite3_context*);
 int sqlite3VdbeParameterIndex(Vdbe*, const char*, int);
 int sqlite3TransferBindings(sqlite3_stmt *, sqlite3_stmt *);
 void sqlite3ParserReset(Parse*);
-void sqlite3ParserAddCleanup(Parse*,void(*)(sqlite3*,void*),void*);
+void *sqlite3ParserAddCleanup(Parse*,void(*)(sqlite3*,void*),void*);
 #ifdef SQLITE_ENABLE_NORMALIZE
 char *sqlite3Normalize(Vdbe*, const char*);
 #endif
@@ -4883,13 +4924,29 @@ const char *sqlite3JournalModename(int);
   int sqlite3WalDefaultHook(void*,sqlite3*,const char*,int);
 #endif
 #ifndef SQLITE_OMIT_CTE
-  With *sqlite3WithAdd(Parse*,With*,Token*,ExprList*,Select*);
+  Cte *sqlite3CteNew(Parse*,Token*,ExprList*,Select*,int);
+  With *sqlite3WithAdd(Parse*,With*,Cte*);
+  void sqlite3CteDelete(sqlite3*,Cte*);
   void sqlite3WithDelete(sqlite3*,With*);
-  void sqlite3WithPush(Parse*, With*, u8);
-#else
-#define sqlite3WithPush(x,y,z)
-#define sqlite3WithDelete(x,y)
-#endif
+  void sqlite3WithReleaseBySelect(sqlite3*,With*);
+  void sqlite3WithReleaseByParse(sqlite3*,With*);
+  void sqlite3WithClaimedBySelect(With*);
+  With *sqlite3WithClaimedByParse(Parse*,With*);
+  void sqlite3WithPush(Parse*, With*);
+# ifdef SQLITE_DEBUG
+    void sqlite3AssertValidCteBackRef(struct SrcList_item*);
+# else
+#   define sqlite3AssertValidCteBackRef(X)
+# endif
+#else /* if defined(SQLITE_OMIT_CTE) */
+# define sqlite3WithPush(PARSE,W)
+# deifne sqlite3WithDelete(Db,W)
+# define sqlite3WithReleaseBySelect(DB,W)
+# define sqlite3WithReleaseByParse(DB,W)
+# define sqlite3WithClaimedBySelect(W)
+# define sqlite3WithClaimedByParse(PARSE,W);
+# define sqlite3AssertValidCteBackRef(X)
+#endif /* SQLITE_OMIT_CTE */
 #ifndef SQLITE_OMIT_UPSERT
   Upsert *sqlite3UpsertNew(sqlite3*,ExprList*,Expr*,ExprList*,Expr*,Upsert*);
   void sqlite3UpsertDelete(sqlite3*,Upsert*);

src/where.c

@@ -2954,9 +2954,9 @@ static int whereLoopAddBtree(
   pWC = pBuilder->pWC;
   assert( !IsVirtual(pSrc->pTab) );
 
-  if( pSrc->pIBIndex ){
+  if( pSrc->fg.isIndexedBy ){
     /* An INDEXED BY clause specifies a particular index to use */
-    pProbe = pSrc->pIBIndex;
+    pProbe = pSrc->u2.pIBIndex;
   }else if( !HasRowid(pTab) ){
     pProbe = pTab->pIndex;
   }else{
@@ -2992,7 +2992,7 @@ static int whereLoopAddBtree(
   if( !pBuilder->pOrSet      /* Not part of an OR optimization */
    && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0
    && (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0
-   && pSrc->pIBIndex==0      /* Has no INDEXED BY clause */
+   && !pSrc->fg.isIndexedBy  /* Has no INDEXED BY clause */
    && !pSrc->fg.notIndexed   /* Has no NOT INDEXED clause */
    && HasRowid(pTab)         /* Not WITHOUT ROWID table. (FIXME: Why not?) */
    && !pSrc->fg.isCorrelated /* Not a correlated subquery */
@@ -3042,7 +3042,7 @@ static int whereLoopAddBtree(
   /* Loop over all indices. If there was an INDEXED BY clause, then only 
   ** consider index pProbe.  */
   for(; rc==SQLITE_OK && pProbe; 
-      pProbe=(pSrc->pIBIndex ? 0 : pProbe->pNext), iSortIdx++
+        pProbe=(pSrc->fg.isIndexedBy ? 0 : pProbe->pNext), iSortIdx++
   ){
     int isLeft = (pSrc->fg.jointype & JT_OUTER)!=0;
     if( pProbe->pPartIdxWhere!=0

tool/mkkeywordhash.c

@@ -229,7 +229,7 @@ static Keyword aKeywordTable[] = {
   { "FOREIGN",          "TK_FOREIGN",      FKEY,             1      },
   { "FROM",             "TK_FROM",         ALWAYS,           10     },
   { "FULL",             "TK_JOIN_KW",      ALWAYS,           3      },
-  { "GENERATED",        "TK_GENERATED",    GENCOL,           1      },
+  { "GENERATED",        "TK_GENERATED",    ALWAYS,           1      },
   { "GLOB",             "TK_LIKE_KW",      ALWAYS,           3      },
   { "GROUP",            "TK_GROUP",        ALWAYS,           5      },
   { "GROUPS",           "TK_GROUPS",       WINDOWFUNC,       2      },
@@ -255,6 +255,7 @@ static Keyword aKeywordTable[] = {
   { "LIKE",             "TK_LIKE_KW",      ALWAYS,           5      },
   { "LIMIT",            "TK_LIMIT",        ALWAYS,           3      },
   { "MATCH",            "TK_MATCH",        ALWAYS,           2      },
+  { "MATERIALIZED",     "TK_MATERIALIZED", CTE,              12     },
   { "NATURAL",          "TK_JOIN_KW",      ALWAYS,           3      },
   { "NO",               "TK_NO",           FKEY|WINDOWFUNC,  2      },
   { "NOT",              "TK_NOT",          ALWAYS,           10     },