From: drh <drh@noemail.net>
Date: Mon, 22 May 2017 00:27:20 +0000 (+0000)
Subject: When planning a query using sorting, resolve ties in the solver by selecting
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b3785b8322b516887bec299a18a32923459e4bcd;p=thirdparty%2Fsqlite.git

When planning a query using sorting, resolve ties in the solver by selecting
loop plans with the smaller unsorted cost.

FossilOrigin-Name: 962531e7c1f3ff604271ddf9f47b6234dfd47702ccf24849f55b80814e7be267
---

diff --git a/manifest b/manifest
index 12a57e3ec2..16f12bf973 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C In\sthe\sSTAT4\scomputations,\sensure\sthat\sthe\saAvgEq\svalues\sdo\snot\sgo\snegative.
-D 2017-01-11T14:21:20.464
+C When\splanning\sa\squery\susing\ssorting,\sresolve\sties\sin\sthe\ssolver\sby\sselecting\nloop\splans\swith\sthe\ssmaller\sunsorted\scost.
+D 2017-05-22T00:27:20.133
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 00d12636df7a5b08af09116bcd6c7bfd49b8b3b4
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -307,7 +307,7 @@ F src/vxworks.h c18586c8edc1bddbc15c004fa16aeb1e1342b4fb
 F src/wal.c 878c8e1a51cb2ec45c395d26b7d5cd9e1a098e4a
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c c253b95b4ee44b21c406e2a1052636c31ea27804
-F src/where.c 8cb63bd44ed75c0abdee39a988255d94153fbb1e
+F src/where.c 688071f74bbf08e838ef1879782325223c2e465d92b845bbf19ce90f6c15d044
 F src/whereInt.h 1d1fd0b3b9b56e08f5d3583c70a2c785a3c43941
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -1250,8 +1250,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 8e4ba115ededca6da78f0679bc9eff08af9365a8
-Q +f58f75b5a06f88ba97bd1a02bee621c64691c6f8
-R c46478f413590926eaa6b50e1920f2e4
+P 4f83f6806aa6816656668feb181369500cc2cf0f
+R abb458770ab34fef4666f2b8a27d0cc7
 U drh
-Z 7b14c592121e5bb4456e4edab32575c6
+Z 12384a5cf88084fac7cfaa713d4c7be3
diff --git a/manifest.uuid b/manifest.uuid
index 18862a59fe..c997916551 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-4f83f6806aa6816656668feb181369500cc2cf0f
\ No newline at end of file
+962531e7c1f3ff604271ddf9f47b6234dfd47702ccf24849f55b80814e7be267
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index ac59fcaab7..faf6d78c5f 100644
--- a/src/where.c
+++ b/src/where.c
@@ -6121,8 +6121,8 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
             ** this candidate as not viable. */
 #ifdef WHERETRACE_ENABLED /* 0x4 */
             if( sqlite3WhereTrace&0x4 ){
-              sqlite3DebugPrintf("Skip   %s cost=%-3d,%3d order=%c\n",
-                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+              sqlite3DebugPrintf("Skip   %s cost=%-3d,%3d,%3d order=%c\n",
+                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
                   isOrdered>=0 ? isOrdered+'0' : '?');
             }
 #endif
@@ -6140,26 +6140,36 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
           pTo = &aTo[jj];
 #ifdef WHERETRACE_ENABLED /* 0x4 */
           if( sqlite3WhereTrace&0x4 ){
-            sqlite3DebugPrintf("New    %s cost=%-3d,%3d order=%c\n",
-                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+            sqlite3DebugPrintf("New    %s cost=%-3d,%3d,%3d order=%c\n",
+                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
                 isOrdered>=0 ? isOrdered+'0' : '?');
           }
 #endif
         }else{
           /* Control reaches here if best-so-far path pTo=aTo[jj] covers the
-          ** same set of loops and has the sam isOrdered setting as the
+          ** same set of loops and has the same isOrdered setting as the
           ** candidate path.  Check to see if the candidate should replace
-          ** pTo or if the candidate should be skipped */
-          if( pTo->rCost<rCost || (pTo->rCost==rCost && pTo->nRow<=nOut) ){
+          ** pTo or if the candidate should be skipped.
+          ** 
+          ** The conditional is an expanded vector comparison equivalent to:
+          **   (pTo->rCost,pTo->nRow,pTo->rUnsorted) <= (rCost,nOut,rUnsorted)
+          */
+          if( pTo->rCost<rCost 
+           || (pTo->rCost==rCost
+               && (pTo->nRow<nOut
+                   || (pTo->nRow==nOut && pTo->rUnsorted<=rUnsorted)
+                  )
+              )
+          ){
 #ifdef WHERETRACE_ENABLED /* 0x4 */
             if( sqlite3WhereTrace&0x4 ){
               sqlite3DebugPrintf(
-                  "Skip   %s cost=%-3d,%3d order=%c",
-                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+                  "Skip   %s cost=%-3d,%3d,%3d order=%c",
+                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
                   isOrdered>=0 ? isOrdered+'0' : '?');
-              sqlite3DebugPrintf("   vs %s cost=%-3d,%d order=%c\n",
+              sqlite3DebugPrintf("   vs %s cost=%-3d,%3d,%3d order=%c\n",
                   wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
-                  pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
+                  pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
             }
 #endif
             /* Discard the candidate path from further consideration */
@@ -6172,12 +6182,12 @@ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
 #ifdef WHERETRACE_ENABLED /* 0x4 */
           if( sqlite3WhereTrace&0x4 ){
             sqlite3DebugPrintf(
-                "Update %s cost=%-3d,%3d order=%c",
-                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
+                "Update %s cost=%-3d,%3d,%3d order=%c",
+                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted,
                 isOrdered>=0 ? isOrdered+'0' : '?');
-            sqlite3DebugPrintf("  was %s cost=%-3d,%3d order=%c\n",
+            sqlite3DebugPrintf("  was %s cost=%-3d,%3d,%3d order=%c\n",
                 wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
-                pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
+                pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?');
           }
 #endif
         }