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Overview
| Comment: | Simplification and performance tweaks in vdbeSorterMerge(). |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | merge-sort |
| Files: | files | file ages | folders |
| SHA1: |
99e34bdce4ccca15b79159b03b96787e |
| User & Date: | drh 2011-09-03 16:42:38 |
Context
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2011-09-03
| ||
| 17:07 | Performance improvements to the external merge-sorter. Keep content on an in-memory linked lists rather than an ephemeral table prior to spilling to disk. Use the external merge-sorter to implement ORDER BY and GROUP BY in addition to CREATE INDEX. (check-in: 4c43e8b2 user: drh tags: trunk) | |
| 16:42 | Simplification and performance tweaks in vdbeSorterMerge(). (Closed-Leaf check-in: 99e34bdc user: drh tags: merge-sort) | |
| 14:36 | Reduce the number of VdbeRecordUnpack() calls made in vdbesort.c. (check-in: 666c2c3c user: dan tags: merge-sort) | |
Changes
Changes to src/vdbesort.c.
486 486 SorterRecord *p1, /* First list to merge */ 487 487 SorterRecord *p2, /* Second list to merge */ 488 488 SorterRecord **ppOut /* OUT: Head of merged list */ 489 489 ){ 490 490 int rc = SQLITE_OK; 491 491 SorterRecord *pFinal = 0; 492 492 SorterRecord **pp = &pFinal; 493 - int bKey2InSpace = 0; /* True if pCsr->aSpace contains key2 */ 493 + void *pVal2 = p2 ? p2->pVal : 0; 494 494 495 - while( p1 || p2 ){ 496 - if( p1==0 ){ 497 - *pp = p2; 498 - p2 = 0; 499 - }else if( p2==0 ){ 495 + while( p1 && p2 ){ 496 + int res; 497 + rc = vdbeSorterCompare(pCsr, 0, p1->pVal, p1->nVal, pVal2, p2->nVal, &res); 498 + if( rc!=SQLITE_OK ){ 499 + *pp = 0; 500 + vdbeSorterRecordFree(db, p1); 501 + vdbeSorterRecordFree(db, p2); 502 + vdbeSorterRecordFree(db, pFinal); 503 + *ppOut = 0; 504 + return rc; 505 + } 506 + if( res<=0 ){ 500 507 *pp = p1; 501 - p1 = 0; 508 + pp = &p1->pNext; 509 + p1 = p1->pNext; 510 + pVal2 = 0; 502 511 }else{ 503 - int res; 504 - rc = vdbeSorterCompare(pCsr, 0, 505 - p1->pVal, p1->nVal, (bKey2InSpace ? 0 : p2->pVal), p2->nVal, &res 506 - ); 507 - if( rc!=SQLITE_OK ){ 508 - vdbeSorterRecordFree(db, p1); 509 - vdbeSorterRecordFree(db, p2); 510 - vdbeSorterRecordFree(db, pFinal); 511 - pFinal = 0; 512 - break; 513 - } 514 - if( res<=0 ){ 515 - *pp = p1; 516 - pp = &p1->pNext; 517 - p1 = p1->pNext; 518 - bKey2InSpace = 1; 519 - }else{ 520 - *pp = p2; 521 - pp = &p2->pNext; 522 - p2 = p2->pNext; 523 - bKey2InSpace = 0; 524 - } 525 - *pp = 0; 512 + *pp = p2; 513 + pp = &p2->pNext; 514 + p2 = p2->pNext; 515 + if( p2==0 ) break; 516 + pVal2 = p2->pVal; 526 517 } 527 518 } 519 + *pp = p1 ? p1 : p2; 528 520 529 521 *ppOut = pFinal; 530 - return rc; 522 + return SQLITE_OK; 531 523 } 532 524 533 525 /* 534 526 ** Sort the linked list of records headed at pCsr->pRecord. Return SQLITE_OK 535 527 ** if successful, or an SQLite error code (i.e. SQLITE_NOMEM) if an error 536 528 ** occurs. 537 529 */