Merge trunk enhancements into the pushdown-subquery branch.

FossilOrigin-Name: 27865e316f8dfbf4c20290cf1be3024d7518fec46655e34f3fc435e15346c63e

manifest

@@ -1,5 +1,5 @@
-C Do\snot\sallow\schanges\sto\ssqlite3ExprIsTableConstant()\sthat\ssupport\spushdown\sof\nsubqueries\sinterfere\swith\sthe\shash-join\slogic.
-D 2024-04-06T18:30:09.352
+C Merge\strunk\senhancements\sinto\sthe\spushdown-subquery\sbranch.
+D 2024-04-07T10:30:29.186
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -700,7 +700,7 @@ F src/date.c 126ba2ab10aeb2e7ba6e089b5f07b747c0625b8287f78b60da346eda8d23c875
 F src/dbpage.c 80e46e1df623ec40486da7a5086cb723b0275a6e2a7b01d9f9b5da0f04ba2782
 F src/dbstat.c 3b677254d512fcafd4d0b341bf267b38b235ccfddbef24f9154e19360fa22e43
 F src/delete.c cb766727c78e715f9fb7ec8a7d03658ed2a3016343ca687acfcec9083cdca500
-F src/expr.c a475049e45329a4586ce8967963784a72023cef0f5821a2265ccacb7f68e0bc6
+F src/expr.c 36071487e377356f1dd62e1e35870ed36a7212cb34ab1578b75d4a27ecdbfcb8
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c a47610f0a5c6cb0ad79f8fcef039c01833dec0c751bb695f28dc0ec6a4c3ba00
 F src/func.c 283d4f3b2751a1d9339fd93a8a013d1948fd5f4474a3cab0955eb4fafd445d0f
@@ -750,12 +750,12 @@ F src/printf.c 87b67bba3662a0523f39ae6b084a3907109702f717c654d6cecb838af5cd57f1
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c f242e509b2ff9e31799d26ddd87f20db1124426203aa16833a694d401b50d650
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 6208d6d4acafc944b9916df28e63fc4e47b922b0335d0db057f68e334b87fc8e
+F src/select.c 51893b3e34d38ad8d46b5010a6e380ca878b578be5001a640daa907336187424
 F src/shell.c.in 0354ca51eee5fbf6af394a7ef9f5ef6823ef45b743db65431f6777e4d5be2199
 F src/sqlite.h.in 32389e0d584551b300d0157881336162c14315a424cbf385c0d65eb7c2e31f7b
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 3f046c04ea3595d6bfda99b781926b17e672fd6d27da2ba6d8d8fc39981dcb54
-F src/sqliteInt.h 257a7addbdb67b1f9f514a28904ed3f574de16bd87c21570faf30600c9c39f40
+F src/sqliteInt.h 4ca38e206befb3738d8cca97b6c6ee56c10f1c5bdb379ac5442d0f1a71b9fefa
 F src/sqliteLimit.h 6878ab64bdeb8c24a1d762d45635e34b96da21132179023338c93f820eee6728
 F src/status.c cb11f8589a6912af2da3bb1ec509a94dd8ef27df4d4c1a97e0bcf2309ece972b
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -837,7 +837,7 @@ F src/wal.h ba252daaa94f889f4b2c17c027e823d9be47ce39da1d3799886bbd51f0490452
 F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
 F src/where.c 09253e913dc1a93aa6e0e1a5d25a392b8fa39096cc30d230dd302264b3be0661
 F src/whereInt.h 82a13766f13d1a53b05387c2e60726289ef26404bc7b9b1f7770204d97357fb8
-F src/wherecode.c 5d77db30a2a3dd532492ae882de114edba2fae672622056b1c7fd61f5917a8f1
+F src/wherecode.c e033875570f5d65b99fdb5189e597d91c8bc34f4196089fd50e6086d174035e7
 F src/whereexpr.c 7b64295f1d82ad0928df435925dd7bbd5997b44a026153113eace0d9e71ff435
 F src/window.c 5d95122dd330bfaebd732358c8ef067c5a9394a53ac249470d611d0ce2c52be2
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@@ -1510,7 +1510,7 @@ F test/printf.test 685fec5a0c5af2490ab0632775a301554361d674211d690f5bee0a97b0533
 F test/printf2.test 3f55c1871a5a65507416076f6eb97e738d5210aeda7595a74ee895f2224cce60
 F test/progress.test ebab27f670bd0d4eb9d20d49cef96e68141d92fb
 F test/ptrchng.test ef1aa72d6cf35a2bbd0869a649b744e9d84977fc
-F test/pushdown.test a8472a771ff80f9652477a688a5beed40b1f6de6546ed3a38150d3b272891173
+F test/pushdown.test 3330746a897ea271b1021bc1e7e57c6f8d49bcb8ca7d58a823d01aa64a303cc7
 F test/queryonly.test 5f653159e0f552f0552d43259890c1089391dcca
 F test/quick.test 1681febc928d686362d50057c642f77a02c62e57
 F test/quickcheck.test a4b7e878cd97e46108291c409b0bf8214f29e18fddd68a42bc5c1375ad1fb80a
@@ -2184,8 +2184,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P a4e1f03dcad70e828a4b56e7a332946daf84d6eae078e3ec9a248b8157a53963
-R d7462427e22b33861c511b137742aefb
+P 8682931f9c6b40e1b09139c10bbe932c38330b5eb0c5c84f2432ad19a6793e37 3d5fb1ec7a0440072d6e3b957903c85d0f32b8b07207a1ef22d1a69cf5e664d1
+R 1c8ec3969a2f62f321843779b94d95c0
 U drh
-Z cfcd3c15df77757710cc4630347f7777
+Z 01f0a53bbc70dd3f39888afc9b26be49
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-8682931f9c6b40e1b09139c10bbe932c38330b5eb0c5c84f2432ad19a6793e37
+27865e316f8dfbf4c20290cf1be3024d7518fec46655e34f3fc435e15346c63e

src/expr.c

@@ -5068,8 +5068,9 @@ expr_code_doover:
       if( !ExprHasProperty(pExpr, EP_Collate) ){
         /* A TK_COLLATE Expr node without the EP_Collate tag is a so-called
         ** "SOFT-COLLATE" that is added to constraints that are pushed down
-        ** from outer queries into sub-queries by the push-down optimization.
-        ** Clear subtypes as subtypes may not cross a subquery boundary.
+        ** from outer queries into sub-queries by the WHERE-clause push-down
+        ** optimization. Clear subtypes as subtypes may not cross a subquery
+        ** boundary.
         */
         assert( pExpr->pLeft );
         sqlite3ExprCode(pParse, pExpr->pLeft, target);

src/select.c

@@ -5060,6 +5060,18 @@ static int pushDownWindowCheck(Parse *pParse, Select *pSubq, Expr *pExpr){
 ** The hope is that the terms added to the inner query will make it more
 ** efficient.
 **
+** NAME AMBIGUITY
+**
+** This optimization is called the "WHERE-clause push-down optimization".
+**
+** Do not confuse this optimization with another unrelated optimization
+** with a similar name:  The "MySQL push-down optimization" causes WHERE
+** clause terms that can be evaluated using only the index and without
+** reference to the table are run first, so that if they are false,
+** unnecessary table seeks are avoided.
+**
+** RULES
+**
 ** Do not attempt this optimization if:
 **
 **   (1) (** This restriction was removed on 2017-09-29.  We used to
@@ -5125,10 +5137,10 @@ static int pushDownWindowCheck(Parse *pParse, Select *pSubq, Expr *pExpr){
 **       (9c) There is a RIGHT JOIN (or FULL JOIN) in between the ON/USING
 **            clause and the subquery.
 **
-**       Without this restriction, the push-down optimization might move
-**       the ON/USING filter expression from the left side of a RIGHT JOIN
-**       over to the right side, which leads to incorrect answers.  See
-**       also restriction (6) in sqlite3ExprIsSingleTableConstraint().
+**       Without this restriction, the WHERE-clause push-down optimization
+**       might move the ON/USING filter expression from the left side of a
+**       RIGHT JOIN over to the right side, which leads to incorrect answers.
+**       See also restriction (6) in sqlite3ExprIsSingleTableConstraint().
 **
 **  (10) The inner query is not the right-hand table of a RIGHT JOIN.
 **
@@ -7689,7 +7701,7 @@ int sqlite3Select(
 #endif
       assert( pItem->pSelect && (pItem->pSelect->selFlags & SF_PushDown)!=0 );
     }else{
-      TREETRACE(0x4000,pParse,p,("Push-down not possible\n"));
+      TREETRACE(0x4000,pParse,p,("WHERE-lcause push-down not possible\n"));
     }
 
     /* Convert unused result columns of the subquery into simple NULL

src/sqliteInt.h

@@ -1906,7 +1906,7 @@ struct sqlite3 {
 #define SQLITE_CursorHints    0x00000400 /* Add OP_CursorHint opcodes */
 #define SQLITE_Stat4          0x00000800 /* Use STAT4 data */
    /* TH3 expects this value  ^^^^^^^^^^ to be 0x0000800. Don't change it */
-#define SQLITE_PushDown       0x00001000 /* The push-down optimization */
+#define SQLITE_PushDown       0x00001000 /* WHERE-clause push-down opt */
 #define SQLITE_SimplifyJoin   0x00002000 /* Convert LEFT JOIN to JOIN */
 #define SQLITE_SkipScan       0x00004000 /* Skip-scans */
 #define SQLITE_PropagateConst 0x00008000 /* The constant propagation opt */
@@ -3580,7 +3580,7 @@ struct Select {
 #define SF_View          0x0200000 /* SELECT statement is a view */
 #define SF_NoopOrderBy   0x0400000 /* ORDER BY is ignored for this query */
 #define SF_UFSrcCheck    0x0800000 /* Check pSrc as required by UPDATE...FROM */
-#define SF_PushDown      0x1000000 /* SELECT has be modified by push-down opt */
+#define SF_PushDown      0x1000000 /* Modified by WHERE-clause push-down opt */
 #define SF_MultiPart     0x2000000 /* Has multiple incompatible PARTITIONs */
 #define SF_CopyCte       0x4000000 /* SELECT statement is a copy of a CTE */
 #define SF_OrderByReqd   0x8000000 /* The ORDER BY clause may not be omitted */

src/wherecode.c

@@ -2474,6 +2474,12 @@ Bitmask sqlite3WhereCodeOneLoopStart(
   ** iLoop==3: Code all remaining expressions.
   **
   ** An effort is made to skip unnecessary iterations of the loop.
+  **
+  ** This optimization of causing simple query restrictions to occur before
+  ** more complex one is call the "push-down" optimization in MySQL.  Here
+  ** in SQLite, the name is "MySQL push-down", since there is also another
+  ** totally unrelated optimization called "WHERE-clause push-down".
+  ** Sometimes the qualifier is omitted, resulting in an ambiguity, so beware.
   */
   iLoop = (pIdx ? 1 : 2);
   do{

test/pushdown.test

@@ -1,4 +1,4 @@
-# 2017 April 29
+# 2017-04-29
 #
 # The author disclaims copyright to this source code.  In place of
 # a legal notice, here is a blessing:
@@ -8,6 +8,26 @@
 #    May you share freely, never taking more than you give.
 #
 #***********************************************************************
+#
+# Test cases for the push-down optimizations.
+#
+#
+# There are two different meanings for "push-down optimization".
+#
+#   (1)  "MySQL push-down" means that WHERE clause terms that can be
+#        evaluated using only the index and without reference to the
+#        table are run first, so that if they are false, unnecessary table
+#        seeks are avoided.  See https://sqlite.org/src/info/d7bb79ed3a40419d
+#        from 2017-04-29.
+#
+#   (2)  "WHERE-clause pushdown" means to push WHERE clause terms in
+#        outer queries down into subqueries.  See
+#        https://sqlite.org/src/info/6df18e949d367629 from 2015-06-02.
+#
+# This module started out as tests for MySQL push-down only.  But because
+# of naming ambiguity, it has picked up test cases for WHERE-clause push-down
+# over the years.
+#
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -87,8 +107,8 @@ do_test 2.2 {
 } {three}
 
 # 2022-11-25 dbsqlfuzz crash-3a548de406a50e896c1bf7142692d35d339d697f
-# Disable the push-down optimization for compound subqueries if any
-# arm of the compound has an incompatible affinity.
+# Disable the WHERE-clause push-down optimization for compound subqueries
+# if any arm of the compound has an incompatible affinity.
 #
 reset_db
 do_execsql_test 3.1 {
@@ -185,7 +205,7 @@ do_eqp_test 3.8 {
 #   SELECT (SELECT count(*) FROM t1)+(SELECT count(*) FROM t2)
 
 # 2023-05-09 https://sqlite.org/forum/forumpost/a7d4be7fb6
-# Restriction (9) on the push-down optimization.
+# Restriction (9) on the WHERE-clause push-down optimization.
 # 
 reset_db
 db null -