From e2d7b24d0845001051956223cccd3eae73fcbd3e Mon Sep 17 00:00:00 2001 From: danielk1977 Date: Mon, 23 Feb 2009 17:33:49 +0000 Subject: [PATCH] Scan an index instead of a table for "SELECT count(*) FROM " queries. Because an index is usually smaller than a table on disk, this saves some IO. (CVS 6315) FossilOrigin-Name: 294ba6f743c9132dce0e73da480bd3c2071e7239 --- manifest | 26 +++++++++++++------------- manifest.uuid | 2 +- src/delete.c | 3 ++- src/expr.c | 3 ++- src/resolve.c | 20 ++++++++++++-------- src/sqliteInt.h | 3 ++- src/update.c | 3 ++- src/where.c | 27 +++++++++++++++++++++------ test/where9.test | 28 +++++++++++++++++++++++++++- 9 files changed, 82 insertions(+), 33 deletions(-) diff --git a/manifest b/manifest index 2d6a18ba59..5120ee23bd 100644 --- a/manifest +++ b/manifest @@ -1,5 +1,5 @@ -C Add\sthe\sreverse_unordered_selects\spragma.\s(CVS\s6314) -D 2009-02-23T16:52:08 +C Scan\san\sindex\sinstead\sof\sa\stable\sfor\s"SELECT\scount(*)\sFROM\s"\squeries.\sBecause\san\sindex\sis\susually\ssmaller\sthan\sa\stable\son\sdisk,\sthis\ssaves\ssome\sIO.\s(CVS\s6315) +D 2009-02-23T17:33:50 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0 F Makefile.in d64baddbf55cdf33ff030e14da837324711a4ef7 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654 @@ -110,8 +110,8 @@ F src/build.c a1db48aec62c95049d783f231195812ff97ae268 F src/callback.c 5f10bca853e59a2c272bbfd5b720303f8b69e520 F src/complete.c cb14e06dbe79dee031031f0d9e686ff306afe07c F src/date.c 0d804df3bbda46329946a01ff5c75c3f4f135218 -F src/delete.c d9172e23f8b524ad23b24cc0dd7cbde8f2aecb54 -F src/expr.c e22112c8db9b82748dd100c716b783cf5d9b6cc5 +F src/delete.c 06e78b6eb53f27acc809a0f69178ea719748bb42 +F src/expr.c 97545fa4058f86c67eb7cacadf60d2964300b00c F src/fault.c dc88c821842157460750d2d61a8a8b4197d047ff F src/func.c 2fb36cd7cc24e16845db203187d1e52811b0fa9c F src/global.c 448419c44ce0701104c2121b0e06919b44514c0c @@ -152,13 +152,13 @@ F src/pragma.c 22ed04836aab8ce134c53be1ca896f3ad20fabdb F src/prepare.c d0bbb4b1a8b9c1db6d13788929839bb63764680e F src/printf.c 9866a9a9c4a90f6d4147407f373df3fd5d5f9b6f F src/random.c 676b9d7ac820fe81e6fb2394ac8c10cff7f38628 -F src/resolve.c b3aa625ec135d53a7e80c86c25ad56de46e0b415 +F src/resolve.c 60a5f405540debee767d8c21ab78a5210b174fa2 F src/rowset.c ba9375f37053d422dd76965a9c370a13b6e1aac4 F src/select.c aa7328a23c0abe019f98bb7e1f4f63d62e20ba98 F src/shell.c f109ebbb50132926ebbc173a6c2d8838d5d78527 F src/sqlite.h.in 14f4d065bafed8500ea558a75a8e2be89c784d61 F src/sqlite3ext.h 1db7d63ab5de4b3e6b83dd03d1a4e64fef6d2a17 -F src/sqliteInt.h c682534d78d7af014c81b30d2c9e75661f4ef990 +F src/sqliteInt.h ac53d3b963c0c98b8f8c6df652a9cde2fd00e987 F src/sqliteLimit.h ffe93f5a0c4e7bd13e70cd7bf84cfb5c3465f45d F src/status.c 237b193efae0cf6ac3f0817a208de6c6c6ef6d76 F src/table.c 332ab0ea691e63862e2a8bdfe2c0617ee61062a3 @@ -195,7 +195,7 @@ F src/test_thread.c adb9175c466e1f487295b5b957603fc0a88ea293 F src/test_wsd.c c297d7d6b8a990239e1bd25935e81d612d8ae31d F src/tokenize.c 6987fb7f0d6a87ac53499aee568cabb05eb4bea8 F src/trigger.c 9957e16e5445478f2cc60e26ac1bc836bb18d21a -F src/update.c fce4fa2945be1a9b65af2acec929669f7d1ac706 +F src/update.c 9c11bc0bba520bcfce47e229a7235a9bc5f9121a F src/utf.c 1da9c832dba0fa8f865b5b902d93f420a1ee4245 F src/util.c 1363f64351f3b544790f3c523439354c02f8c4e9 F src/vacuum.c 4929a585ef0fb1dfaf46302f8a9c4aa30c2d9cf5 @@ -208,7 +208,7 @@ F src/vdbeblob.c 08d6bac666c1f6a5d67452f5fbf808cf1311d2c9 F src/vdbemem.c 543a79d722734d2f8b7ad70f08218c30bcc5bbf5 F src/vtab.c e39e011d7443a8d574b1b9cde207a35522e6df43 F src/walker.c 42bd3f00ca2ef5ae842304ec0d59903ef051412d -F src/where.c 72980baae14e7e71dc70c671b6cf34c4063dbd58 +F src/where.c 591db2b9bc4d65b60ab28554eb40dc357358c47a F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2 F test/alias.test 597662c5d777a122f9a3df0047ea5c5bd383a911 F test/all.test 14165b3e32715b700b5f0cbf8f6e3833dda0be45 @@ -673,7 +673,7 @@ F test/where6.test 42c4373595f4409d9c6a9987b4a60000ad664faf F test/where7.test 2487cda68faabf5edeb524289913f00f8d64e223 F test/where8.test 1b9152a086408ee789166d0a954abc597372f868 F test/where8m.test c1010d61826412ff66abd29bfb32e5d6b37d965c -F test/where9.test a46d394037a40b56e7855d29cce951f91108c353 +F test/where9.test 0e44fd96a838f7fa9ecd39a6569bfc4bd446faad F test/whereA.test ef8d699d87934bd747119c75fbb4711b584a8b60 F test/wherelimit.test 5e9fd41e79bb2b2d588ed999d641d9c965619b31 F test/zeroblob.test 792124852ec61458a2eb527b5091791215e0be95 @@ -701,7 +701,7 @@ F tool/speedtest16.c c8a9c793df96db7e4933f0852abb7a03d48f2e81 F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e -P 9b8acf8319ec760713773407a4d5a33dea8d75e8 -R 41bbb1216086db2d528bb92c681c2add -U drh -Z 08cd8c8feaad5119cbc7d91cd8c2e6b1 +P bc078e0007b6c3dc07722820bb53798b643212b3 +R 19edfff27399a21c42d0d895b28d7f0b +U danielk1977 +Z 309cb578835963c08d5f7f73ef6b305b diff --git a/manifest.uuid b/manifest.uuid index c78d008e84..1b5a46bce2 100644 --- a/manifest.uuid +++ b/manifest.uuid @@ -1 +1 @@ -bc078e0007b6c3dc07722820bb53798b643212b3 \ No newline at end of file +294ba6f743c9132dce0e73da480bd3c2071e7239 \ No newline at end of file diff --git a/src/delete.c b/src/delete.c index 5ad7327551..b70352c874 100644 --- a/src/delete.c +++ b/src/delete.c @@ -12,7 +12,7 @@ ** This file contains C code routines that are called by the parser ** in order to generate code for DELETE FROM statements. ** -** $Id: delete.c,v 1.193 2009/02/20 10:58:42 danielk1977 Exp $ +** $Id: delete.c,v 1.194 2009/02/23 17:33:50 danielk1977 Exp $ */ #include "sqliteInt.h" @@ -395,6 +395,7 @@ void sqlite3DeleteFrom( /* Collect rowids of every row to be deleted. */ sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet); + pTabList->a[0].usesRowid = 1; pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, WHERE_FILL_ROWSET, iRowSet); if( pWInfo==0 ) goto delete_from_cleanup; diff --git a/src/expr.c b/src/expr.c index af99382203..4b92d6c0f6 100644 --- a/src/expr.c +++ b/src/expr.c @@ -12,7 +12,7 @@ ** This file contains routines used for analyzing expressions and ** for generating VDBE code that evaluates expressions in SQLite. ** -** $Id: expr.c,v 1.414 2009/02/20 10:58:42 danielk1977 Exp $ +** $Id: expr.c,v 1.415 2009/02/23 17:33:50 danielk1977 Exp $ */ #include "sqliteInt.h" @@ -931,6 +931,7 @@ SrcList *sqlite3SrcListDup(sqlite3 *db, SrcList *p, int flags){ pNewItem->pOn = sqlite3ExprDup(db, pOldItem->pOn, flags); pNewItem->pUsing = sqlite3IdListDup(db, pOldItem->pUsing); pNewItem->colUsed = pOldItem->colUsed; + pNewItem->usesRowid = pOldItem->usesRowid; } return pNew; } diff --git a/src/resolve.c b/src/resolve.c index af44730eff..29f1f2b929 100644 --- a/src/resolve.c +++ b/src/resolve.c @@ -14,7 +14,7 @@ ** resolve all identifiers by associating them with a particular ** table and column. ** -** $Id: resolve.c,v 1.16 2009/02/19 14:39:25 danielk1977 Exp $ +** $Id: resolve.c,v 1.17 2009/02/23 17:33:50 danielk1977 Exp $ */ #include "sqliteInt.h" #include @@ -347,14 +347,18 @@ static int lookupName( ** column number is greater than the number of bits in the bitmask ** then set the high-order bit of the bitmask. */ - if( pExpr->iColumn>=0 && pMatch!=0 ){ - int n = pExpr->iColumn; - testcase( n==BMS-1 ); - if( n>=BMS ){ - n = BMS-1; + if( pMatch ){ + if( pExpr->iColumn>=0 ){ + int n = pExpr->iColumn; + testcase( n==BMS-1 ); + if( n>=BMS ){ + n = BMS-1; + } + assert( pMatch->iCursor==pExpr->iTable ); + pMatch->colUsed |= ((Bitmask)1)<usesRowid = 1; } - assert( pMatch->iCursor==pExpr->iTable ); - pMatch->colUsed |= ((Bitmask)1)<a[0].usesRowid = 1; pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, WHERE_ONEPASS_DESIRED, 0); if( pWInfo==0 ) goto update_cleanup; diff --git a/src/where.c b/src/where.c index ea6e00a802..e76fc11cb4 100644 --- a/src/where.c +++ b/src/where.c @@ -16,7 +16,7 @@ ** so is applicable. Because this module is responsible for selecting ** indices, you might also think of this module as the "query optimizer". ** -** $Id: where.c,v 1.371 2009/02/23 16:52:08 drh Exp $ +** $Id: where.c,v 1.372 2009/02/23 17:33:50 danielk1977 Exp $ */ #include "sqliteInt.h" @@ -1715,15 +1715,15 @@ static double bestVirtualIndex( ** * Whether or not there must be separate lookups in the ** index and in the main table. ** -** If there was an INDEXED BY clause attached to the table in the SELECT -** statement, then this function only considers plans using the +** If there was an INDEXED BY clause (pSrc->pIndex) attached to the table in +** the SQL statement, then this function only considers plans using the ** named index. If one cannot be found, then the returned cost is ** SQLITE_BIG_DBL. If a plan can be found that uses the named index, ** then the cost is calculated in the usual way. ** -** If a NOT INDEXED clause was attached to the table in the SELECT -** statement, then no indexes are considered. However, the selected -** plan may still take advantage of the tables built-in rowid +** If a NOT INDEXED clause (pSrc->notIndexed!=0) was attached to the table +** in the SELECT statement, then no indexes are considered. However, the +** selected plan may still take advantage of the tables built-in rowid ** index. */ static void bestIndex( @@ -2035,6 +2035,21 @@ static void bestIndex( } } + if( pCost->plan.wsFlags==0 && pSrc->colUsed==0 && pSrc->usesRowid==0 ){ + Index *pSmallest = 0; + assert( pSrc->pIndex==0 ); + for(pProbe=pSrc->pTab->pIndex; pProbe; pProbe=pProbe->pNext){ + if( !pSmallest || pProbe->nColumnnColumn ){ + pSmallest = pProbe; + } + } + if( pSmallest && pSmallest->nColumnpTab->nCol ){ + assert( pCost->plan.nEq==0 ); + pCost->plan.u.pIdx = pSmallest; + pCost->plan.wsFlags = WHERE_COLUMN_RANGE|WHERE_IDX_ONLY; + } + } + /* Report the best result */ pCost->plan.wsFlags |= eqTermMask; diff --git a/test/where9.test b/test/where9.test index c8921c7172..f0c7a61534 100644 --- a/test/where9.test +++ b/test/where9.test @@ -11,7 +11,7 @@ # This file implements regression tests for SQLite library. The # focus of this file is testing the multi-index OR clause optimizer. # -# $Id: where9.test,v 1.5 2009/01/08 21:00:03 drh Exp $ +# $Id: where9.test,v 1.6 2009/02/23 17:33:50 danielk1977 Exp $ set testdir [file dirname $argv0] source $testdir/tester.tcl @@ -802,4 +802,30 @@ do_test where9-6.8.2 { } } {1 {cannot use index: t1b}} +do_test where9-7.1 { + execsql { + CREATE TABLE t5(a, b, c); + EXPLAIN QUERY PLAN SELECT count(*) FROM t5; + } +} {0 0 {TABLE t5}} +do_test where9-7.2 { + execsql { + CREATE INDEX t5i1 ON t5(a, b); + EXPLAIN QUERY PLAN SELECT count(*) FROM t5; + } +} {0 0 {TABLE t5 WITH INDEX t5i1}} +do_test where9-7.3 { + execsql { + CREATE INDEX t5i2 ON t5(b); + EXPLAIN QUERY PLAN SELECT count(*) FROM t5; + } +} {0 0 {TABLE t5 WITH INDEX t5i2}} +do_test where9-7.4 { + execsql { + CREATE TABLE t6(a, b, c); + CREATE INDEX t6i1 ON t6(a, b, c); + EXPLAIN QUERY PLAN SELECT count(*) FROM t6; + } +} {0 0 {TABLE t6}} + finish_test