From: drh <>
Date: Sat, 31 May 2025 16:17:14 +0000 (+0000)
Subject: Relax query flattener constraint (3b) and thereby allow flattening the RHS of
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=52486939249c1104572b8c45563de19f600e7f96;p=thirdparty%2Fsqlite.git

Relax query flattener constraint (3b) and thereby allow flattening the RHS of
a LEFT JOIN even if the RHS contains a virtual table.  This was previously
disallowed by [9dbae1df75219e2a] as a performance optimization.  It
turns out that the constraint causes performance issues, and we do not have
a record of any performance issue that it solves.

FossilOrigin-Name: 1ddaa92057e550ea281d45d9860eafe69399224725548a93dd91c47a34e52152
---

diff --git a/manifest b/manifest
index edb2fc0aed..26c77b26aa 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Move\sa\smis-located\smakefile\scomment\sblock.
-D 2025-05-31T11:08:06.337
+C Relax\squery\sflattener\sconstraint\s(3b)\sand\sthereby\sallow\sflattening\sthe\sRHS\sof\na\sLEFT\sJOIN\seven\sif\sthe\sRHS\scontains\sa\svirtual\stable.\s\sThis\swas\spreviously\ndisallowed\sby\s[9dbae1df75219e2a]\sas\sa\sperformance\soptimization.\s\sIt\nturns\sout\sthat\sthe\sconstraint\scauses\sperformance\sissues,\sand\swe\sdo\snot\shave\na\srecord\sof\sany\sperformance\sissue\sthat\sit\ssolves.
+D 2025-05-31T16:17:14.990
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -785,7 +785,7 @@ F src/printf.c 3b91c334f528359145f4dde0dedd945bbb21044d0825ea064934d7222d61662c
 F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c d40fe18d7c2fd0339f5846ffcf7d6809866e380acdf14c76fb2af87e9fe13f64
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
-F src/select.c 5145c03d216cf3cd5b0101b77ce2e8d7e2f1622f07a03d0783a8f80c83ca110f
+F src/select.c d0dfddf0ded00913570263ed6ef46878efd2a7c824233fd3904c81e4d05bc923
 F src/shell.c.in ba53a52dafb167ac6320703da741386c34fbcabe8c078a188bb9f89808e3ef8f
 F src/sqlite.h.in 22882ddd3a70751aa8864c81993ee4562ed54c2c508b6270f75e223ffee38e1b
 F src/sqlite3.rc 015537e6ac1eec6c7050e17b616c2ffe6f70fca241835a84a4f0d5937383c479
@@ -1222,7 +1222,7 @@ F test/fts3fault3.test ccdd2292dd2d4e21e30fc5f4c8e064f79e516087eec5ff57ab6bc4f6a
 F test/fts3first.test dbdedd20914c8d539aa3206c9b34a23775644641
 F test/fts3fuzz001.test c78afcd8ad712ea0b8d2ed50851a8aab3bc9dc52c64a536291e07112f519357c
 F test/fts3integrity.test 0c6fe7353d7b24d78862f4272ee9df4da2f32b3ff30fa3396945cda8119580a8
-F test/fts3join.test 1a4d786539b2b79a41c28ef2ac22cacd92a8ee830249b68a7dee4a020848e3bb
+F test/fts3join.test de31d304ba479043a7d33d2f201c514b3e1da809da6797d7a58704d00e8da2e6
 F test/fts3malloc.test b0e4c133b8d61d4f6d112d8110f8320e9e453ef6
 F test/fts3matchinfo.test aa66cc50615578b30f6df9984819ae5b702511cf8a94251ec7c594096a703a4a
 F test/fts3matchinfo2.test 00144e841704b8debfcdf6097969cd9f2a1cf759e2203cda42583648f2e6bf58
@@ -2207,8 +2207,8 @@ F tool/version-info.c 3b36468a90faf1bbd59c65fd0eb66522d9f941eedd364fabccd7227350
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
 F tool/warnings.sh 1ad0169b022b280bcaaf94a7fa231591be96b514230ab5c98fbf15cd7df842dd
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 413a626b5c7902c1810142536c36e4ea8ee7c616ea82dfe1114199f9319091f7
-R 0a66ec57047a402dd75f80b24d811cb0
-U stephan
-Z b135e4a3d41689a53dcec5acda960e8c
+P 7d884386bec11f47c2c18002dd8c573c9b5cb6f7cdf2307a96cccead05b6abf2
+R 52b5e04212112150fc1a41026d6d393f
+U drh
+Z e8f3cf7347e28213896d8a300a9e60bd
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 789684a762..87cb14bcb2 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-7d884386bec11f47c2c18002dd8c573c9b5cb6f7cdf2307a96cccead05b6abf2
+1ddaa92057e550ea281d45d9860eafe69399224725548a93dd91c47a34e52152
diff --git a/src/select.c b/src/select.c
index a8af934e42..8eaf5e2b65 100644
--- a/src/select.c
+++ b/src/select.c
@@ -4245,9 +4245,9 @@ static int compoundHasDifferentAffinities(Select *p){
 **             from 2015-02-09.)
 **
 **   (3)  If the subquery is the right operand of a LEFT JOIN then
-**        (3a) the subquery may not be a join and
-**        (3b) the FROM clause of the subquery may not contain a virtual
-**             table and
+**        (3a) the subquery may not be a join
+**        (**) Was (3b): "the FROM clause of the subquery may not contain
+**             a virtual table"
 **        (**) Was: "The outer query may not have a GROUP BY." This case
 **             is now managed correctly
 **        (3d) the outer query may not be DISTINCT.
@@ -4463,7 +4463,7 @@ static int flattenSubquery(
   */
   if( (pSubitem->fg.jointype & (JT_OUTER|JT_LTORJ))!=0 ){
     if( pSubSrc->nSrc>1                        /* (3a) */
-     || IsVirtual(pSubSrc->a[0].pSTab)         /* (3b) */
+     /**** || IsVirtual(pSubSrc->a[0].pSTab)      (3b)-omitted */
      || (p->selFlags & SF_Distinct)!=0         /* (3d) */
      || (pSubitem->fg.jointype & JT_RIGHT)!=0  /* (26) */
     ){
diff --git a/test/fts3join.test b/test/fts3join.test
index cbd08b63f2..9171c817be 100644
--- a/test/fts3join.test
+++ b/test/fts3join.test
@@ -97,11 +97,8 @@ do_eqp_test 4.2 {
   WHERE t4.y = ?;
 } {
   QUERY PLAN
-  |--MATERIALIZE rr
-  |  `--SCAN ft4 VIRTUAL TABLE INDEX 3:
   |--SCAN t4
-  |--BLOOM FILTER ON rr (docid=?)
-  `--SEARCH rr USING AUTOMATIC COVERING INDEX (docid=?) LEFT-JOIN
+  `--SCAN ft4 VIRTUAL TABLE INDEX 3: LEFT-JOIN
 }
 
 finish_test