The 0x8000 optimization flag associated with SQLITE_TESTCTRL_OPTIMIZATIONS

causes a large penalty (200) to be added to all sorting costs, which
encourages the query planner avoid using the sorter. This flag can be
used in experiments to help come up with a more accurate estimate of the
true cost of sorting.

FossilOrigin-Name: 857a1b01df45e30991510e57b7b195406fffe9c9c4c82cfd54dbd97c38820fb3

manifest

@@ -1,5 +1,5 @@
-C Add\san\sALWAYS\son\san\sunreachable\sbranch\sin\sthe\sALTER\sTABLE\slogic.
-D 2018-10-03T18:05:36.483
+C The\s0x8000\soptimization\sflag\sassociated\swith\sSQLITE_TESTCTRL_OPTIMIZATIONS\ncauses\sa\slarge\spenalty\s(200)\sto\sbe\sadded\sto\sall\ssorting\scosts,\swhich\nencourages\sthe\squery\splanner\savoid\susing\sthe\ssorter.\sThis\sflag\scan\sbe\nused\sin\sexperiments\sto\shelp\scome\sup\swith\sa\smore\saccurate\sestimate\sof\sthe\ntrue\scost\sof\ssorting.
+D 2018-10-04T18:17:11.635
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in 01e95208a78b57d056131382c493c963518f36da4c42b12a97eb324401b3a334
@@ -508,7 +508,7 @@ F src/shell.c.in 6046da2a92998b8fe004ed4eadd4d7f53d6a8e4d99e5e25a0cc7de6de5f6b26
 F src/sqlite.h.in 4b4c2f2daeeed4412ba9d81bc78092c69831fe6eda4f0ae5bf951da51a8dccec
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 305adca1b5da4a33ce2db5bd236935768e951d5651bfe5560ed55cfcdbce6a63
-F src/sqliteInt.h 75d8266b27c287aeada717a541cf7b7543383fccdb1d7d45a5620f666e864c55
+F src/sqliteInt.h 00532747dba7ef01ac6d9a2f38884b414af7f258c2798368e181ff95dc8d0541
 F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
 F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -588,7 +588,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 3f4f653daf234fe713edbcbca3fec2350417d159d28801feabc702a22c4e213f
 F src/wal.h 606292549f5a7be50b6227bd685fa76e3a4affad71bb8ac5ce4cb5c79f6a176a
 F src/walker.c fb94aadc9099ff9c6506d0a8b88d51266005bcaa265403f3d7caf732a562eb66
-F src/where.c a54a3d639bcd751d1474deff58e239b2e475a96e1b8f9178aa7864df8782a4e3
+F src/where.c 824ca57fcf4e7fd7064c006a14620e755f4e1a965606914efba8aaf5ed1acafd
 F src/whereInt.h f125f29fca80890768e0b2caa14f95db74b2dacd3a122a168f97aa7b64d6968f
 F src/wherecode.c 3df0a541373d5f999684d761e4bd700d57adb46c7d39da4e77b767b5adcd5893
 F src/whereexpr.c 1b5a5a7876997f65232bbf19c5c1eeb47eb328b8fa5b28c865543052904cde00
@@ -1614,7 +1614,7 @@ F test/walrofault.test c70cb6e308c443867701856cce92ad8288cd99488fa52afab77cca6cf
 F test/walshared.test 0befc811dcf0b287efae21612304d15576e35417
 F test/walslow.test c05c68d4dc2700a982f89133ce103a1a84cc285f
 F test/walthread.test 14b20fcfa6ae152f5d8e12f5dc8a8a724b7ef189f5d8ef1e2ceab79f2af51747
-F test/where.test 480cfc1758ac9df3f70c6a2541ff586f6a4833354d5ecb548f643e30e31fddc8
+F test/where.test 6bfcd29db193b814e5736832ffa899b4ff2969a106b718a79375063d5eb02b29
 F test/where2.test 478d2170637b9211f593120648858593bf2445a1
 F test/where3.test 2341a294e17193a6b1699ea7f192124a5286ca6acfcc3f4b06d16c931fbcda2c
 F test/where4.test 4a371bfcc607f41d233701bdec33ac2972908ba8
@@ -1770,7 +1770,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P bf0a6634cd8f9457992b8da522a6775a304156815bf6f4f64f96016356baa870
-R 3bd57e9abfbbe1b0866f4f1caa5677e9
+P ebcd4523171f0988ff08e2bf36fb8a0caa40efe7ac7556b4eb206784969b03e4
+R 642c0bb5a644a972b78ebd27bbacf467
+T *branch * query-planner-debug
+T *sym-query-planner-debug *
+T -sym-trunk *
 U drh
-Z 12be36416a19f9505215ac2168bb7434
+Z 095d6087f014d31add31769becb73bab

manifest.uuid

@@ -1 +1 @@
-ebcd4523171f0988ff08e2bf36fb8a0caa40efe7ac7556b4eb206784969b03e4
+857a1b01df45e30991510e57b7b195406fffe9c9c4c82cfd54dbd97c38820fb3

src/sqliteInt.h

@@ -1393,6 +1393,7 @@ struct sqlite3 {
   u8 mTrace;                    /* zero or more SQLITE_TRACE flags */
   u8 noSharedCache;             /* True if no shared-cache backends */
   u8 nSqlExec;                  /* Number of pending OP_SqlExec opcodes */
+  LogEst iSortCost;             /* Extra cost applied to sorting */
   int nextPagesize;             /* Pagesize after VACUUM if >0 */
   u32 magic;                    /* Magic number for detect library misuse */
   int nChange;                  /* Value returned by sqlite3_changes() */
@@ -1561,7 +1562,7 @@ struct sqlite3 {
 ** selectively disable various optimizations.
 */
 #define SQLITE_QueryFlattener 0x0001   /* Query flattening */
-                          /*  0x0002   available for reuse */
+#define SQLITE_PropagateConst 0x0002   /* The constant propagation opt */
 #define SQLITE_GroupByOrder   0x0004   /* GROUPBY cover of ORDERBY */
 #define SQLITE_FactorOutConst 0x0008   /* Constant factoring */
 #define SQLITE_DistinctOpt    0x0010   /* DISTINCT using indexes */
@@ -1576,7 +1577,7 @@ struct sqlite3 {
 #define SQLITE_PushDown       0x1000   /* The push-down optimization */
 #define SQLITE_SimplifyJoin   0x2000   /* Convert LEFT JOIN to JOIN */
 #define SQLITE_SkipScan       0x4000   /* Skip-scans */
-#define SQLITE_PropagateConst 0x8000   /* The constant propagation opt */
+#define SQLITE_SortIfFaster   0x8000   /* ORDER BY using sorter if faster */
 #define SQLITE_AllOpts        0xffff   /* All optimizations */
 
 /*

src/where.c

@@ -4109,11 +4109,13 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
                 pWInfo, nRowEst, nOrderBy, isOrdered
             );
           }
-          /* TUNING:  Add a small extra penalty (5) to sorting as an
-          ** extra encouragment to the query planner to select a plan
-          ** where the rows emerge in the correct order without any sorting
-          ** required. */
-          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]) + 5;
+          rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]);
+          if( OptimizationDisabled(db, SQLITE_SortIfFaster) ){
+            /* if the SortIfFaster optimization is disabled, then set the
+            ** sort cost very high, to encourage the query to return the
+            ** results in natural order, if at all possible */
+            rCost += 200;
+          }
 
           WHERETRACE(0x002,
               ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",

test/where.test

@@ -582,7 +582,7 @@ do_test where-6.7.2 {
   cksort {
     SELECT * FROM t3 WHERE b>0 ORDER BY a LIMIT 1
   }
-} {1 100 4 nosort}
+} {1 100 4 sort}
 ifcapable subquery {
   do_test where-6.8a {
     cksort {