When using an index to scan a database table, read column data from the index in preference to the table. This increases the likelihood that the table will not be required at all. (CVS 4580)
FossilOrigin-Name: 061608c72ac0a96eacf3b64d638235e4739f96ba
This commit is contained in:
danielk1977
@@ -1,5 +1,5 @@
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C Optimisations\sfor\sexpressions\sof\sthe\sform\s"<value>\sIN\s(SELECT\s<column>\sFROM\s<table>)".\s(CVS\s4579)
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D 2007-11-29T17:05:18
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C When\susing\san\sindex\sto\sscan\sa\sdatabase\stable,\sread\scolumn\sdata\sfrom\sthe\sindex\sin\spreference\sto\sthe\stable.\sThis\sincreases\sthe\slikelihood\sthat\sthe\stable\swill\snot\sbe\srequired\sat\sall.\s(CVS\s4580)
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D 2007-11-29T17:43:28
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F Makefile.arm-wince-mingw32ce-gcc ac5f7b2cef0cd850d6f755ba6ee4ab961b1fadf7
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F Makefile.in 35396fd58890420b29edcf27b6c0e2d054862a6b
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F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
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@@ -176,7 +176,7 @@ F src/vdbeblob.c 82f51cdf9b0c0af729732fde48c824e498c0a1ca
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F src/vdbefifo.c 334c838c8f42d61a94813d136019ee566b5dc2f6
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F src/vdbemem.c 123994fcd344993d2fb050a83b91b341bbbd08b4
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F src/vtab.c f819d55ef638d45e09ce00009d435da8bf16f528
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F src/where.c a03cd9da865f9ae9d750b01b45ad0bd82bd456f1
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F src/where.c 7ec7c7a5b3a534d5ccbe9d73690b8969ee6b3f08
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F tclinstaller.tcl 4356d9d94d2b5ed5e68f9f0c80c4df3048dd7617
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F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
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F test/all.test ee350b9ab15b175fc0a8fb51bf2141ed3a3b9cba
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@@ -336,7 +336,7 @@ F test/insert3.test 9a4ef3526fd3cca8b05278020ec3100448b4c677
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F test/insert4.test 6919ddacd79c2cfeb9785b0f84217f9cb14853b5
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F test/insert5.test e8d5ba31283db5b0315ada9774dd99b6e9fe2122
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F test/interrupt.test 81555fb0f8179bb2d0dc7151fd75428223f93cf2
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F test/intpkey.test af4fd826c4784ec5c93b444de07adea0254d0d30
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F test/intpkey.test 537669fd535f62632ca64828e435b9e54e8d677f
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F test/io.test 80a7a7f1a2792e037d447b03e8c22ee1f6eaf339
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F test/ioerr.test ae429185a3a11a318aa7ec64e2188e6119e43bca
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F test/ioerr2.test e3d52c40f43f9b61da9b38951a737e7b84ebae96
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@@ -509,7 +509,7 @@ F test/vtabA.test 9cb6b1afead6fdd91bbdf1ca65c44ccfd9b10936
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F test/vtab_alter.test b0c0f61a9588b509c2ba20dedc2db04999da6656
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F test/vtab_err.test 0d4d8eb4def1d053ac7c5050df3024fd47a3fbd8
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F test/vtab_shared.test d631d1f820c38c18939d53aab1fc35db5f0a8094
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F test/where.test 1bcde8984c63747ac6d6bafcacd20fd6e8a223de
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F test/where.test 5ff4a1bda6352b73354faf1a97706bbfa0d47dfe
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F test/where2.test 9bbf1cc675730954047d663e4c0dc5d4c9669ca4
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F test/where3.test 0a30fe9808b0fa01c46d0fcf4fac0bf6cf75bb30
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F test/where4.test 1b1cd72d5f205ce34d5a31f3c4918f833e5e6a63
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@@ -594,7 +594,7 @@ F www/tclsqlite.tcl 8be95ee6dba05eabcd27a9d91331c803f2ce2130
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F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
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F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
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F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
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P 221aee72be040769e8026b91648f03c6366a8821
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R 17bc1550023a2d1b2bcf36adaf1ceda3
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P 56d0e32677744df8570b519fae1c04da4ea4984d
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R 36e691e0ba7fd3d68c366765c689ffb2
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U danielk1977
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Z 90a3ecb3d9566cd903183cf31905697c
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Z 64a9f02b9181db1b1e3b35c33464441d
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+1
-1
@@ -1 +1 @@
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56d0e32677744df8570b519fae1c04da4ea4984d
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061608c72ac0a96eacf3b64d638235e4739f96ba
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+12
-10
@@ -16,7 +16,7 @@
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** so is applicable. Because this module is responsible for selecting
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** indices, you might also think of this module as the "query optimizer".
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**
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** $Id: where.c,v 1.264 2007/11/29 17:05:18 danielk1977 Exp $
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** $Id: where.c,v 1.265 2007/11/29 17:43:28 danielk1977 Exp $
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*/
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#include "sqliteInt.h"
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@@ -2215,10 +2215,6 @@ WhereInfo *sqlite3WhereBegin(
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VdbeComment((v, "# %s", pIx->zName));
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sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum,
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(char*)pKey, P3_KEYINFO_HANDOFF);
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}
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if( (pLevel->flags & (WHERE_IDX_ONLY|WHERE_COLUMN_RANGE))!=0 ){
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/* Only call OP_SetNumColumns on the index if we might later use
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** OP_Column on the index. */
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sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1);
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}
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sqlite3CodeVerifySchema(pParse, iDb);
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@@ -2742,8 +2738,12 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
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sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0);
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}
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/* Make cursor substitutions for cases where we want to use
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** just the index and never reference the table.
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/* If this scan uses an index, make code substitutions to read data
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** from the index in preference to the table. Sometimes, this means
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** the table need never be read from. This is a performance boost,
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** as the vdbe level waits until the table is read before actually
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** seeking the table cursor to the record corresponding to the current
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** position in the index.
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**
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** Calls to the code generator in between sqlite3WhereBegin and
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** sqlite3WhereEnd will have created code that references the table
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@@ -2751,10 +2751,11 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
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** that reference the table and converts them into opcodes that
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** reference the index.
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*/
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if( pLevel->flags & WHERE_IDX_ONLY ){
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if( pLevel->pIdx ){
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int k, j, last;
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VdbeOp *pOp;
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Index *pIdx = pLevel->pIdx;
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int useIndexOnly = pLevel->flags & WHERE_IDX_ONLY;
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assert( pIdx!=0 );
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pOp = sqlite3VdbeGetOp(v, pWInfo->iTop);
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@@ -2762,17 +2763,18 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
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for(k=pWInfo->iTop; k<last; k++, pOp++){
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if( pOp->p1!=pLevel->iTabCur ) continue;
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if( pOp->opcode==OP_Column ){
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pOp->p1 = pLevel->iIdxCur;
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for(j=0; j<pIdx->nColumn; j++){
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if( pOp->p2==pIdx->aiColumn[j] ){
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pOp->p2 = j;
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pOp->p1 = pLevel->iIdxCur;
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break;
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}
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}
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assert(!useIndexOnly || j<pIdx->nColumn);
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}else if( pOp->opcode==OP_Rowid ){
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pOp->p1 = pLevel->iIdxCur;
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pOp->opcode = OP_IdxRowid;
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}else if( pOp->opcode==OP_NullRow ){
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}else if( pOp->opcode==OP_NullRow && useIndexOnly ){
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pOp->opcode = OP_Noop;
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}
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}
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+2
-2
@@ -13,7 +13,7 @@
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# This file implements tests for the special processing associated
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# with INTEGER PRIMARY KEY columns.
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#
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# $Id: intpkey.test,v 1.23 2005/07/21 03:48:20 drh Exp $
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# $Id: intpkey.test,v 1.24 2007/11/29 17:43:28 danielk1977 Exp $
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set testdir [file dirname $argv0]
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source $testdir/tester.tcl
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@@ -293,7 +293,7 @@ do_test intpkey-3.8 {
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count {
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SELECT * FROM t1 WHERE c=='world' AND a>7;
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}
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} {11 hello world 5}
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} {11 hello world 4}
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do_test intpkey-3.9 {
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count {
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SELECT * FROM t1 WHERE 7<a;
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+7
-7
@@ -1,4 +1,4 @@
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# 2001 September 15
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# 4 2001 September 15
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#
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# The author disclaims copyright to this source code. In place of
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# a legal notice, here is a blessing:
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@@ -11,7 +11,7 @@
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# This file implements regression tests for SQLite library. The
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# focus of this file is testing the use of indices in WHERE clases.
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#
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# $Id: where.test,v 1.43 2007/06/25 16:29:34 danielk1977 Exp $
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# $Id: where.test,v 1.44 2007/11/29 17:43:28 danielk1977 Exp $
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set testdir [file dirname $argv0]
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source $testdir/tester.tcl
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@@ -184,7 +184,7 @@ do_test where-1.25 {
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do_test where-1.27 {
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count {SELECT w FROM t1 WHERE x=3 AND y+1==122}
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} {10 17}
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} {10 10}
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do_test where-1.28 {
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count {SELECT w FROM t1 WHERE x+1=4 AND y+1==122}
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@@ -358,7 +358,7 @@ ifcapable subquery {
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count {
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SELECT * FROM t1 WHERE rowid+0 IN (1,2,3,1234) order by 1;
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}
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} {1 0 4 2 1 9 3 1 16 199}
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} {1 0 4 2 1 9 3 1 16 102}
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do_test where-5.3 {
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count {
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SELECT * FROM t1 WHERE w IN (-1,1,2,3) order by 1;
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@@ -368,7 +368,7 @@ ifcapable subquery {
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count {
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SELECT * FROM t1 WHERE w+0 IN (-1,1,2,3) order by 1;
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}
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} {1 0 4 2 1 9 3 1 16 199}
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} {1 0 4 2 1 9 3 1 16 102}
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do_test where-5.5 {
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count {
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SELECT * FROM t1 WHERE rowid IN
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@@ -382,7 +382,7 @@ ifcapable subquery {
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(select rowid from t1 where rowid IN (-1,2,4))
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ORDER BY 1;
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}
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} {2 1 9 4 2 25 201}
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} {2 1 9 4 2 25 103}
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do_test where-5.7 {
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count {
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SELECT * FROM t1 WHERE w IN
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@@ -396,7 +396,7 @@ ifcapable subquery {
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(select rowid from t1 where rowid IN (-1,2,4))
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ORDER BY 1;
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}
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} {2 1 9 4 2 25 201}
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} {2 1 9 4 2 25 103}
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do_test where-5.9 {
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count {
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SELECT * FROM t1 WHERE x IN (1,7) ORDER BY 1;
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