From: drh <drh@noemail.net>
Date: Sat, 9 Jun 2018 14:13:46 +0000 (+0000)
Subject: Improved comments an presentation for the recent IN operator decision
X-Git-Tag: version-3.25.0~201
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a46ba6cca5102ade4689faeb67a499d56360ebb7;p=thirdparty%2Fsqlite.git

Improved comments an presentation for the recent IN operator decision
improvement.

FossilOrigin-Name: 31e480f68dfd887cfd9114f9f9fec53d751d3ecc27e36f55c0166b51b2fbb08c
---

diff --git a/manifest b/manifest
index 735c33f57b..2408ba2066 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Performance\simprovement\sto\ssqlite3WhereExprUsage().
-D 2018-06-09T02:49:11.362
+C Improved\scomments\san\spresentation\sfor\sthe\srecent\sIN\soperator\sdecision\nimprovement.
+D 2018-06-09T14:13:46.495
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in bfc40f350586923e0419d2ea4b559c37ec10ee4b6e210e08c14401f8e340f0da
@@ -579,7 +579,7 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c aa9cffc7a2bad6b826a86c8562dd4978398720ed41cb8ee7aa9d054eb8b456a0
 F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
 F src/walker.c da987a20d40145c0a03c07d8fefcb2ed363becc7680d0500d9c79915591f5b1f
-F src/where.c 9915929594a8c6bf8ca8d6e02a4f7e632948fa523712ab647490d18855a43656
+F src/where.c fe1a6f97c12cc9472ccce86166ba3f827cf61d6ae770c036a6396b63863baac4
 F src/whereInt.h b90ef9b9707ef750eab2a7a080c48fb4900315033274689def32d0cf5a81ebe4
 F src/wherecode.c 3317f2b083a66d3e65a03edf316ade4ccb0a99c9956273282ebb579b95d4ba96
 F src/whereexpr.c 6f022d6cc9daf56495f191b199352f783aff5cf268ba136b4d8cea3fb62d8c7d
@@ -1731,7 +1731,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P d735872ec383bbd220b08c61d25db9ff3675d2542b9e7867e7d6323a12e0cc23
-R 2ba2d88f21c46106179a39d7ea349a11
+P fd0934139076848f2f2edfd3d74d54608531031a05a60ca6ac1d7016dcd538df
+R b9ed4417ad4e47d1ad0ea2ffe1b71005
 U drh
-Z 5dc11e9a5cd95e10cd947ae661eb7994
+Z fc8a0aeffe4e41486a64c0cdfcf48c75
diff --git a/manifest.uuid b/manifest.uuid
index c6ce388e64..e6f6c75858 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fd0934139076848f2f2edfd3d74d54608531031a05a60ca6ac1d7016dcd538df
\ No newline at end of file
+31e480f68dfd887cfd9114f9f9fec53d751d3ecc27e36f55c0166b51b2fbb08c
\ No newline at end of file
diff --git a/src/where.c b/src/where.c
index 56d37be012..0e47dbf7ee 100644
--- a/src/where.c
+++ b/src/where.c
@@ -2451,7 +2451,6 @@ static int whereLoopAddBtreeIndex(
 
     if( eOp & WO_IN ){
       Expr *pExpr = pTerm->pExpr;
-      LogEst M, logK;
       if( ExprHasProperty(pExpr, EP_xIsSelect) ){
         /* "x IN (SELECT ...)":  TUNING: the SELECT returns 25 rows */
         int i;
@@ -2472,6 +2471,7 @@ static int whereLoopAddBtreeIndex(
                           ** changes "x IN (?)" into "x=?". */
       }
       if( pProbe->hasStat1 ){
+        LogEst M, logK, safetyMargin;
         /* Let:
         **   N = the total number of rows in the table
         **   K = the number of entries on the RHS of the IN operator
@@ -2493,7 +2493,8 @@ static int whereLoopAddBtreeIndex(
         */
         M = pProbe->aiRowLogEst[saved_nEq];
         logK = estLog(nIn);
-        if( M + logK + 10 < nIn + rLogSize ){
+        safetyMargin = 10;  /* TUNING: extra weight for indexed IN */
+        if( M + logK + safetyMargin < nIn + rLogSize ){
           WHERETRACE(0x40,
             ("Scan preferred over IN operator on column %d of \"%s\" (%d<%d)\n",
              saved_nEq, pProbe->zName, M+logK+10, nIn+rLogSize));