From: drh <drh@noemail.net>
Date: Fri, 16 Nov 2018 19:19:58 +0000 (+0000)
Subject: Update the explain virtual table to make use of SQLITE_CONSTRAINT.
X-Git-Tag: version-3.26.0~31
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d16f26a7088719f75b00f5a433d635770fcb941d;p=thirdparty%2Fsqlite.git

Update the explain virtual table to make use of SQLITE_CONSTRAINT.

FossilOrigin-Name: b2d41ff7027b44ccb5dffc303c47d42f1f6fd66ce22e90450d3a666c73fe8b8e
---

diff --git a/ext/misc/explain.c b/ext/misc/explain.c
index dc0c9d7669..7a2fc4776a 100644
--- a/ext/misc/explain.c
+++ b/ext/misc/explain.c
@@ -18,6 +18,10 @@
 **     .load ./explain
 **     SELECT p2 FROM explain('SELECT * FROM sqlite_master')
 **      WHERE opcode='OpenRead';
+**
+** This module was originally written to help simplify SQLite testing,
+** by providing an easier means of verifying certain patterns in the
+** generated bytecode.
 */
 #if !defined(SQLITEINT_H)
 #include "sqlite3ext.h"
@@ -232,23 +236,31 @@ static int explainBestIndex(
   sqlite3_vtab *tab,
   sqlite3_index_info *pIdxInfo
 ){
-  int i;
+  int i;                  /* Loop counter */
+  int idx = -1;           /* Index of a usable == constraint against SQL */
+  int unusable = 0;       /* True if there are unusable constraints on SQL */
 
-  pIdxInfo->estimatedCost = (double)1000000;
   pIdxInfo->estimatedRows = 500;
   for(i=0; i<pIdxInfo->nConstraint; i++){
     struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[i];
-    if( p->usable
-     && p->iColumn==EXPLN_COLUMN_SQL
-     && p->op==SQLITE_INDEX_CONSTRAINT_EQ
-    ){
-      pIdxInfo->estimatedCost = 10.0;
-      pIdxInfo->idxNum = 1;
-      pIdxInfo->aConstraintUsage[i].argvIndex = 1;
-      pIdxInfo->aConstraintUsage[i].omit = 1;
-      break;
+    if( p->iColumn!=EXPLN_COLUMN_SQL ) continue;
+    if( !p->usable ){
+      unusable = 1;
+    }else if( p->op==SQLITE_INDEX_CONSTRAINT_EQ ){
+      idx = i;
     }
   }
+  if( idx>=0 ){
+    /* There exists a usable == constraint against the SQL column */
+    pIdxInfo->estimatedCost = 10.0;
+    pIdxInfo->idxNum = 1;
+    pIdxInfo->aConstraintUsage[idx].argvIndex = 1;
+    pIdxInfo->aConstraintUsage[idx].omit = 1;
+  }else if( unusable ){
+    /* There are unusable constraints against the SQL column.  Do not allow
+    ** this plan to continue forward. */
+    return SQLITE_CONSTRAINT;
+  }
   return SQLITE_OK;
 }
 
diff --git a/manifest b/manifest
index 18b3168a74..559a5ebd89 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sthe\sJSON\stable-valued\sfunctions\sto\smake\suse\sof\sSQLITE_CONSTRAINT.
-D 2018-11-16T16:04:50.796
+C Update\sthe\sexplain\svirtual\stable\sto\smake\suse\sof\sSQLITE_CONSTRAINT.
+D 2018-11-16T19:19:58.887
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in b730006b54c990461d864c5387f2e6f13aadb0236804555fb010ed6865a5f058
@@ -281,7 +281,7 @@ F ext/misc/compress.c dd4f8a6d0baccff3c694757db5b430f3bbd821d8686d1fc24df55cf9f0
 F ext/misc/csv.c 88333dc9f7dcf6a8148406f10ae04261e24e3b4c721550ae33e9e71f1265c1f1
 F ext/misc/dbdump.c 12389a10c410fadf1e68eeb382def92d5a7fa9ce7cce4fb86a736fa2bac1000a
 F ext/misc/eval.c 6ea9b22a5fa0dd973b67ca4e53555be177bc0b7b263aadf1024429457c82c0e3
-F ext/misc/explain.c c82dd86f1156d32b284e0523a4bf6a93a85ab2a812caed48963e0774f3327185
+F ext/misc/explain.c d5c12962d79913ef774b297006872af1fccda388f61a11d37758f9179a09551f
 F ext/misc/fileio.c e3153b04433897a18a3d17185845f286892e96fdf87f4301290d09c36ae1759f
 F ext/misc/fuzzer.c 7c64b8197bb77b7d64eff7cac7848870235d4c25
 F ext/misc/ieee754.c f190d0cc5182529acb15babd177781be1ac1718c
@@ -1778,7 +1778,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P cd13b499a20a7d476edb8500537edef4c5151410ba0300469ebf0f7ba16964b8
-R 11042163bdaf90fd68f04b94be6dfff4
+P 3f34f4f561c77f8ec88906818f2984dcf8f17d1645bac175e9027595517560bc
+R bb2adeaa580d1c642edf2f21d75f48f2
 U drh
-Z 7ed31881cc0f31c278a8f140145ccdcf
+Z f6b6b46a521f0bb21911f77fd6557c2e
diff --git a/manifest.uuid b/manifest.uuid
index 2d3c3f40b3..fa71cc2fab 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-3f34f4f561c77f8ec88906818f2984dcf8f17d1645bac175e9027595517560bc
\ No newline at end of file
+b2d41ff7027b44ccb5dffc303c47d42f1f6fd66ce22e90450d3a666c73fe8b8e
\ No newline at end of file