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Overview
Comment: | 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) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
061608c72ac0a96eacf3b64d638235e4 |
User & Date: | danielk1977 2007-11-29 17:43:28.000 |
Context
2007-11-29
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18:36 | Add the optional (and experimental) mmap() memory allocator in the mem4.c module. (CVS 4581) (check-in: cfd683ac80 user: drh tags: trunk) | |
17:43 | 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) (check-in: 061608c72a user: danielk1977 tags: trunk) | |
17:05 |
Optimisations for expressions of the form "<value> IN (SELECT <column> FROM | |
Changes
Changes to src/where.c.
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12 13 14 15 16 17 18 | ** This module contains C code that generates VDBE code used to process ** the WHERE clause of SQL statements. This module is reponsible for ** generating the code that loops through a table looking for applicable ** rows. Indices are selected and used to speed the search when doing ** so is applicable. Because this module is responsible for selecting ** indices, you might also think of this module as the "query optimizer". ** | | | 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | ** This module contains C code that generates VDBE code used to process ** the WHERE clause of SQL statements. This module is reponsible for ** generating the code that loops through a table looking for applicable ** rows. Indices are selected and used to speed the search when doing ** 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 1.265 2007/11/29 17:43:28 danielk1977 Exp $ */ #include "sqliteInt.h" /* ** The number of bits in a Bitmask. "BMS" means "BitMask Size". */ #define BMS (sizeof(Bitmask)*8) |
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2211 2212 2213 2214 2215 2216 2217 | if( (pIx = pLevel->pIdx)!=0 ){ KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx); assert( pIx->pSchema==pTab->pSchema ); sqlite3VdbeAddOp(v, OP_Integer, iDb, 0); VdbeComment((v, "# %s", pIx->zName)); sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum, (char*)pKey, P3_KEYINFO_HANDOFF); | < < < < | 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 | if( (pIx = pLevel->pIdx)!=0 ){ KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx); assert( pIx->pSchema==pTab->pSchema ); sqlite3VdbeAddOp(v, OP_Integer, iDb, 0); VdbeComment((v, "# %s", pIx->zName)); sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum, (char*)pKey, P3_KEYINFO_HANDOFF); sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1); } sqlite3CodeVerifySchema(pParse, iDb); } pWInfo->iTop = sqlite3VdbeCurrentAddr(v); /* Generate the code to do the search. Each iteration of the for |
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2738 2739 2740 2741 2742 2743 2744 | if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){ sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0); } if( pLevel->pIdx!=0 ){ sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0); } | | > > > > | | > < > > | | 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 | if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){ sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0); } if( pLevel->pIdx!=0 ){ sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0); } /* If this scan uses an index, make code substitutions to read data ** from the index in preference to the table. Sometimes, this means ** the table need never be read from. This is a performance boost, ** as the vdbe level waits until the table is read before actually ** seeking the table cursor to the record corresponding to the current ** position in the index. ** ** Calls to the code generator in between sqlite3WhereBegin and ** sqlite3WhereEnd will have created code that references the table ** directly. This loop scans all that code looking for opcodes ** that reference the table and converts them into opcodes that ** reference the index. */ if( pLevel->pIdx ){ int k, j, last; VdbeOp *pOp; Index *pIdx = pLevel->pIdx; int useIndexOnly = pLevel->flags & WHERE_IDX_ONLY; assert( pIdx!=0 ); pOp = sqlite3VdbeGetOp(v, pWInfo->iTop); last = sqlite3VdbeCurrentAddr(v); for(k=pWInfo->iTop; k<last; k++, pOp++){ if( pOp->p1!=pLevel->iTabCur ) continue; if( pOp->opcode==OP_Column ){ for(j=0; j<pIdx->nColumn; j++){ if( pOp->p2==pIdx->aiColumn[j] ){ pOp->p2 = j; pOp->p1 = pLevel->iIdxCur; break; } } assert(!useIndexOnly || j<pIdx->nColumn); }else if( pOp->opcode==OP_Rowid ){ pOp->p1 = pLevel->iIdxCur; pOp->opcode = OP_IdxRowid; }else if( pOp->opcode==OP_NullRow && useIndexOnly ){ pOp->opcode = OP_Noop; } } } } /* Final cleanup */ whereInfoFree(pWInfo); return; } |
Changes to test/intpkey.test.
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9 10 11 12 13 14 15 | # #*********************************************************************** # This file implements regression tests for SQLite library. # # This file implements tests for the special processing associated # with INTEGER PRIMARY KEY columns. # | | | 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | # #*********************************************************************** # This file implements regression tests for SQLite library. # # This file implements tests for the special processing associated # with INTEGER PRIMARY KEY columns. # # $Id: intpkey.test,v 1.24 2007/11/29 17:43:28 danielk1977 Exp $ set testdir [file dirname $argv0] source $testdir/tester.tcl # Create a table with a primary key and a datatype other than # integer # |
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289 290 291 292 293 294 295 | SELECT * FROM t1 WHERE c=='world'; } } {5 hello world 11 hello world 5} do_test intpkey-3.8 { count { SELECT * FROM t1 WHERE c=='world' AND a>7; } | | | 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 | SELECT * FROM t1 WHERE c=='world'; } } {5 hello world 11 hello world 5} do_test intpkey-3.8 { count { SELECT * FROM t1 WHERE c=='world' AND a>7; } } {11 hello world 4} do_test intpkey-3.9 { count { SELECT * FROM t1 WHERE 7<a; } } {11 hello world 1} # Test inequality constraints on integer primary keys and rowids |
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Changes to test/where.test.
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| | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | # 4 2001 September 15 # # The author disclaims copyright to this source code. In place of # a legal notice, here is a blessing: # # May you do good and not evil. # May you find forgiveness for yourself and forgive others. # May you share freely, never taking more than you give. # #*********************************************************************** # This file implements regression tests for SQLite library. The # focus of this file is testing the use of indices in WHERE clases. # # $Id: where.test,v 1.44 2007/11/29 17:43:28 danielk1977 Exp $ set testdir [file dirname $argv0] source $testdir/tester.tcl # Build some test data # do_test where-1.0 { |
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180 181 182 183 184 185 186 | # # do_test where-1.26 { # count {SELECT w FROM t1 WHERE x=3 AND y BETWEEN 121 AND 196} # } {10 11 12 13 9} do_test where-1.27 { count {SELECT w FROM t1 WHERE x=3 AND y+1==122} | | | 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 | # # do_test where-1.26 { # count {SELECT w FROM t1 WHERE x=3 AND y BETWEEN 121 AND 196} # } {10 11 12 13 9} do_test where-1.27 { count {SELECT w FROM t1 WHERE x=3 AND y+1==122} } {10 10} do_test where-1.28 { count {SELECT w FROM t1 WHERE x+1=4 AND y+1==122} } {10 99} do_test where-1.29 { count {SELECT w FROM t1 WHERE y==121} } {10 99} |
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354 355 356 357 358 359 360 | SELECT * FROM t1 WHERE rowid IN (1,2,3,1234) order by 1; } } {1 0 4 2 1 9 3 1 16 4} do_test where-5.2 { count { SELECT * FROM t1 WHERE rowid+0 IN (1,2,3,1234) order by 1; } | | | | | | 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 | SELECT * FROM t1 WHERE rowid IN (1,2,3,1234) order by 1; } } {1 0 4 2 1 9 3 1 16 4} do_test where-5.2 { count { SELECT * FROM t1 WHERE rowid+0 IN (1,2,3,1234) order by 1; } } {1 0 4 2 1 9 3 1 16 102} do_test where-5.3 { count { SELECT * FROM t1 WHERE w IN (-1,1,2,3) order by 1; } } {1 0 4 2 1 9 3 1 16 14} do_test where-5.4 { count { SELECT * FROM t1 WHERE w+0 IN (-1,1,2,3) order by 1; } } {1 0 4 2 1 9 3 1 16 102} do_test where-5.5 { count { SELECT * FROM t1 WHERE rowid IN (select rowid from t1 where rowid IN (-1,2,4)) ORDER BY 1; } } {2 1 9 4 2 25 3} do_test where-5.6 { count { SELECT * FROM t1 WHERE rowid+0 IN (select rowid from t1 where rowid IN (-1,2,4)) ORDER BY 1; } } {2 1 9 4 2 25 103} do_test where-5.7 { count { SELECT * FROM t1 WHERE w IN (select rowid from t1 where rowid IN (-1,2,4)) ORDER BY 1; } } {2 1 9 4 2 25 9} do_test where-5.8 { count { SELECT * FROM t1 WHERE w+0 IN (select rowid from t1 where rowid IN (-1,2,4)) ORDER BY 1; } } {2 1 9 4 2 25 103} do_test where-5.9 { count { SELECT * FROM t1 WHERE x IN (1,7) ORDER BY 1; } } {2 1 9 3 1 16 7} do_test where-5.10 { count { |
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