From: drh <drh@noemail.net>
Date: Mon, 22 Feb 2016 20:52:26 +0000 (+0000)
Subject: Avoid an unnecessary seek operation on some corner-case skip-scans.
X-Git-Tag: version-3.12.0~155^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a6d2f8eb1e2e1be45ac52106fd31eb8c5c81f7f5;p=thirdparty%2Fsqlite.git

Avoid an unnecessary seek operation on some corner-case skip-scans.

FossilOrigin-Name: 38e837e605076124b73235e1fd832838d9545cb2
---

diff --git a/manifest b/manifest
index ee22164613..14f3934982 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Always\suse\sthe\ssqlite3VdbeDeleteAuxdata()\sroutine\sfor\sclearing\sauxdata\son\nfunction\sparameter,\srather\sthan\shaving\sa\sseparate\sdeleteAuxdataFromFrame()\nfor\sdoing\sthe\sjob\sfor\strigger\sframes.
-D 2016-02-22T16:04:31.519
+C Avoid\san\sunnecessary\sseek\soperation\son\ssome\scorner-case\sskip-scans.
+D 2016-02-22T20:52:26.579
 F Makefile.in 4e90dc1521879022aa9479268a4cd141d1771142
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 28fc4ee02333996d31b3602b39eeb8e609a89ce4
@@ -430,7 +430,7 @@ F src/wal.h 2f7c831cf3b071fa548bf2d5cac640846a7ff19c
 F src/walker.c 0f142b5bd3ed2041fc52d773880748b212e63354
 F src/where.c 5b67fb8035ae4697cf721db095f800ef8dff5f56
 F src/whereInt.h 78b6b4de94db84aecbdc07fe3e38f648eb391e9a
-F src/wherecode.c 791a784bbf8749d560fdb0b990b607bc4f44a38d
+F src/wherecode.c 19aa0189a6088f8fde9105839b00be77f85d4469
 F src/whereexpr.c fb87944b1254234e5bba671aaf6dee476241506a
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test a6d901b436328bd67a79b41bb0ac2663918fe3bd
@@ -1429,7 +1429,10 @@ F tool/vdbe_profile.tcl 246d0da094856d72d2c12efec03250d71639d19f
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh a98af506df552f3b3c0d904f94e4cdc4e1a6d598
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 3ed1890612bd45bd9c72f670d2cbb0b8fbd35d92
-R 087e6cf717ab51d03c5c0e76eb47f593
+P 64386fa339adb91439da979d74062f67a6ec68fd
+R a08f482677879c74e73ef75af70e8b9f
+T *branch * skip-scan-improvement
+T *sym-skip-scan-improvement *
+T -sym-trunk *
 U drh
-Z ce8b779f1a9ea7c56d4a99bdf5d3c13f
+Z 08bae61bde61749b6ce2ce908b2beeb6
diff --git a/manifest.uuid b/manifest.uuid
index e6907d43a9..e2a870a8f3 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-64386fa339adb91439da979d74062f67a6ec68fd
\ No newline at end of file
+38e837e605076124b73235e1fd832838d9545cb2
\ No newline at end of file
diff --git a/src/wherecode.c b/src/wherecode.c
index bb48e5dc70..34e166bc48 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -1212,17 +1212,19 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       start_constraints = 1;
     }
     codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);
-    op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
-    assert( op!=0 );
-    sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
-    VdbeCoverage(v);
-    VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
-    VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
-    VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
-    VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
-    VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
-    VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );
-
+    if( pLoop->nSkip==0 || nConstraint>pLoop->nSkip ){
+      op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
+      assert( op!=0 );
+      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
+      VdbeCoverage(v);
+      VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
+      VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
+      VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
+      VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
+      VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
+      VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );
+    }
+    
     /* Load the value for the inequality constraint at the end of the
     ** range (if any).
     */