From: drh <>
Date: Fri, 15 Jul 2022 20:39:39 +0000 (+0000)
Subject: In the query planner, restore the former aggressiveness in reordering of
X-Git-Tag: version-3.40.0~297
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=02cb3ff0044a07fdefb782e375d536548e965cf5;p=thirdparty%2Fsqlite.git

In the query planner, restore the former aggressiveness in reordering of
FROM clause terms that existed prior to version 3.39.0 for queries that
contain no RIGHT or FULL JOINs.

FossilOrigin-Name: 92d60b64ebfc2d1f0a9cabaa88e7bf0d11737ed01a77b627af10dd1b96a5321c
---

diff --git a/manifest b/manifest
index 4c513ab28f..c90ff11a61 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sa\smemory\sleak\sin\sfts3\sthat\scould\soccur\swhen\sprocessing\sa\scorrupt\sdatabase.
-D 2022-07-15T15:08:48.874
+C In\sthe\squery\splanner,\srestore\sthe\sformer\saggressiveness\sin\sreordering\sof\nFROM\sclause\sterms\sthat\sexisted\sprior\sto\sversion\s3.39.0\sfor\squeries\sthat\ncontain\sno\sRIGHT\sor\sFULL\sJOINs.
+D 2022-07-15T20:39:39.491
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -657,7 +657,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c b9df133a705093da8977da5eb202eaadb844839f1c7297c08d33471f5491843d
 F src/wal.h c3aa7825bfa2fe0d85bef2db94655f99870a285778baa36307c0a16da32b226a
 F src/walker.c f890a3298418d7cba3b69b8803594fdc484ea241206a8dfa99db6dd36f8cbb3b
-F src/where.c c7e96c036d2bf0755a2bedf796951ff8bf0dd062b07c4ccc724e1432c3dcf5db
+F src/where.c 1049685e84bd74692ad76984a3411a21c5a1e6ddd08c981ec94d2f11f769e07f
 F src/whereInt.h b48ca529ffe293c18cbfa8326af18a09e39910de66fb3e96ef788c7cbf8ef3a7
 F src/wherecode.c 0b09abfcb88c61c6a6984a3e065786631ff35495e9bdf865e6b74ab0a1299c5b
 F src/whereexpr.c 55a39f42aaf982574fbf52906371a84cceed98a994422198dfd03db4fce4cc46
@@ -1980,8 +1980,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0620e419a927a3da6ebe921aaa3471686f0fdc2e485f4c2d5c88f32092228724
-R b9aac4d9609cc8841634db9ea3e3fcba
-U dan
-Z bb096f0e437aaa23189ce1ee6aae46bf
+P d74f6f6d5136995b8bf900eb671e4b15ca81e03cc1ab5b7a1aa43dc4f3617760
+R fa54dcdbc827a4bcf8d891638157443e
+U drh
+Z 2feb16b88bfbd559419278240c03d9ae
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 78ed53ebc3..41fe746559 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d74f6f6d5136995b8bf900eb671e4b15ca81e03cc1ab5b7a1aa43dc4f3617760
\ No newline at end of file
+92d60b64ebfc2d1f0a9cabaa88e7bf0d11737ed01a77b627af10dd1b96a5321c
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 3dd5058fc9..6f3402a6e4 100644
--- a/src/where.c
+++ b/src/where.c
@@ -4181,6 +4181,7 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
   sqlite3 *db = pWInfo->pParse->db;
   int rc = SQLITE_OK;
   int bFirstPastRJ = 0;
+  int hasRightJoin = 0;
   WhereLoop *pNew;
 
 
@@ -4207,15 +4208,16 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
       ** prevents the right operand of a RIGHT JOIN from being swapped with
       ** other elements even further to the right.
       **
-      ** The JT_LTORJ term prevents any FROM-clause term reordering for terms
-      ** to the left of a RIGHT JOIN.  This is conservative.  Relaxing this
-      ** constraint somewhat to prevent terms from crossing from the right
-      ** side of a LEFT JOIN over to the left side when they are on the
-      ** left side of a RIGHT JOIN would be sufficient for all known failure
-      ** cases.  FIX ME: Implement this optimization.
+      ** The JT_LTORJ case and the hasRightJoin flag work together to
+      ** prevent FROM-clause terms from moving from the right side of
+      ** a LEFT JOIN over to the left side of that join if the LEFT JOIN
+      ** is itself on the left side of a RIGHT JOIN.
       */
+      if( pItem->fg.jointype & JT_LTORJ ) hasRightJoin = 1;
       mPrereq |= mPrior;
       bFirstPastRJ = (pItem->fg.jointype & JT_RIGHT)!=0;
+    }else if( !hasRightJoin ){
+      mPrereq = 0;
     }
 #ifndef SQLITE_OMIT_VIRTUALTABLE
     if( IsVirtual(pItem->pTab) ){