From c04ea80f64ea05beec16cbaf2dbb98a105bf96b6 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Thu, 13 Apr 2017 19:48:29 +0000
Subject: [PATCH] Simplification of the skip-ahead-distinct logic.  There is
 still an issue with handling COLLATE.

FossilOrigin-Name: 57c5173b6376a76013b0611ce9770100bd8c04e80402e35d821d8614709f4795
---
 manifest      | 14 +++++++-------
 manifest.uuid |  2 +-
 src/where.c   | 31 +++++++++++++++----------------
 3 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/manifest b/manifest
index 3c64591e00..b74a3d4f87 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C New\stest\scases\sand\sminor\sfixes\sfor\sthe\soptimization\son\sthis\sbranch.
-D 2017-04-13T18:33:33.610
+C Simplification\sof\sthe\sskip-ahead-distinct\slogic.\s\sThere\sis\sstill\san\sissue\nwith\shandling\sCOLLATE.
+D 2017-04-13T19:48:29.675
 F Makefile.in 1cc758ce3374a32425e4d130c2fe7b026b20de5b8843243de75f087c0a2661fb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc a4c0613a18663bda56d8cf76079ab6590a7c3602e54befb4bbdef76bcaa38b6a
@@ -482,7 +482,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 40c543f0a2195d1b0dc88ef12142bea690009344
 F src/wal.h 06b2a0b599cc0f53ea97f497cf8c6b758c999f71
 F src/walker.c b71a992b413b3a022572eccf29ef4b4890223791
-F src/where.c b08b998bea4474754bbb54a4d22e9689e4372672f9cd8ccc4d41640ef5efecbf
+F src/where.c 2b88a9abe28584178a395f286479dda0b103a758c3bf3c70e52a0560f40b467d
 F src/whereInt.h 7a21ef633e26acbf46df04add2eba6e0a2100c78dc5879049e93f981fc3344df
 F src/wherecode.c 943e32e9dccd0af802e0683ae11071c8bd808364e5908a5fb66758bd404c8681
 F src/whereexpr.c e913aaa7b73ffcce66abcea5f197e2c538d48b5df78d0b7bba8ff4d73cc2e745
@@ -1572,7 +1572,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0cf16decd534bf2d66620c293f8c8987f356305f2d97f8fd12d260bda1571385
-R 576a06d609b733a5644f1c6a0bebf58e
-U dan
-Z e29dec34fd75469b8282367092cf6782
+P 70ac9ea1a6cb2f4906f00f1a04f668e5ba5eeed8d4d0fa4be57a9c9eb0683697
+R a148756c1ff7d66b58143c3257e91f62
+U drh
+Z 90de4c6922e024a076aa3621c058524e
diff --git a/manifest.uuid b/manifest.uuid
index 05244214c1..b718a572c9 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-70ac9ea1a6cb2f4906f00f1a04f668e5ba5eeed8d4d0fa4be57a9c9eb0683697
\ No newline at end of file
+57c5173b6376a76013b0611ce9770100bd8c04e80402e35d821d8614709f4795
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index a846e2e822..dbb8111d14 100644
--- a/src/where.c
+++ b/src/where.c
@@ -3437,7 +3437,7 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
 }
 
 /*
-** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
+** Examine a WherePath (with the addition of the extra WhereLoop of the 6th
 ** parameters) to see if it outputs rows in the requested ORDER BY
 ** (or GROUP BY) without requiring a separate sort operation.  Return N:
 ** 
@@ -4849,6 +4849,7 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
     pLoop = pLevel->pWLoop;
     if( pLevel->op!=OP_Noop ){
 #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
+      int addrSeek = 0;
       int n = -1;
       int j, k, op;
       int r1 = pParse->nMem+1;
@@ -4897,25 +4898,23 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
         }
         pParse->nMem += n;
         op = pLevel->op==OP_Prev ? OP_SeekLT : OP_SeekGT;
-        k = sqlite3VdbeAddOp4Int(v, op, pLevel->iIdxCur, 0, r1, n);
+        addrSeek = sqlite3VdbeAddOp4Int(v, op, pLevel->iIdxCur, 0, r1, n);
         VdbeCoverageIf(v, op==OP_SeekLT);
         VdbeCoverageIf(v, op==OP_SeekGT);
         sqlite3VdbeAddOp2(v, OP_Goto, 1, pLevel->p2);
-        sqlite3VdbeResolveLabel(v, pLevel->addrCont);
-        sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
-        sqlite3VdbeJumpHere(v, k);
-      }else
-#endif /* SQLITE_DISABLE_SKIPAHEAD_DISTINCT */
-      {
-        /* The common case: Advance to the next row */
-        sqlite3VdbeResolveLabel(v, pLevel->addrCont);
-        sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
-        sqlite3VdbeChangeP5(v, pLevel->p5);
-        VdbeCoverage(v);
-        VdbeCoverageIf(v, pLevel->op==OP_Next);
-        VdbeCoverageIf(v, pLevel->op==OP_Prev);
-        VdbeCoverageIf(v, pLevel->op==OP_VNext);
       }
+#endif /* SQLITE_DISABLE_SKIPAHEAD_DISTINCT */
+      /* The common case: Advance to the next row */
+      sqlite3VdbeResolveLabel(v, pLevel->addrCont);
+      sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
+      sqlite3VdbeChangeP5(v, pLevel->p5);
+      VdbeCoverage(v);
+      VdbeCoverageIf(v, pLevel->op==OP_Next);
+      VdbeCoverageIf(v, pLevel->op==OP_Prev);
+      VdbeCoverageIf(v, pLevel->op==OP_VNext);
+#ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
+      if( addrSeek ) sqlite3VdbeJumpHere(v, addrSeek);
+#endif
     }else{
       sqlite3VdbeResolveLabel(v, pLevel->addrCont);
     }