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Overview
Comment: | Bias the b-tree binary search toward the high end. The common case is to append data and this heuristic makes append run much faster because there are fewer comparisons. (CVS 3740) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
a9877f616b24737152627841fcbd80cc |
User & Date: | drh 2007-03-29 04:43:26.000 |
Context
2007-03-29
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05:51 | Change BtreeMoveto so that it can be biased to the right or to the center. Use a right bias when appending and a center bias when searching. This gives about a 15% reduction in calls to sqlite3VdbeRecordCompare. (CVS 3741) (check-in: ad4a6b1a91 user: drh tags: trunk) | |
04:43 | Bias the b-tree binary search toward the high end. The common case is to append data and this heuristic makes append run much faster because there are fewer comparisons. (CVS 3740) (check-in: a9877f616b user: drh tags: trunk) | |
02:26 | Get LEMON working again when YYSTACKDEPTH is greater than zero. (CVS 3739) (check-in: e72c81dbb3 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
1 2 3 4 5 6 7 8 9 10 11 | /* ** 2004 April 6 ** ** 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. ** ************************************************************************* | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | /* ** 2004 April 6 ** ** 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. ** ************************************************************************* ** $Id: btree.c,v 1.344 2007/03/29 04:43:26 drh Exp $ ** ** This file implements a external (disk-based) database using BTrees. ** For a detailed discussion of BTrees, refer to ** ** Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3: ** "Sorting And Searching", pages 473-480. Addison-Wesley ** Publishing Company, Reading, Massachusetts. |
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3301 3302 3303 3304 3305 3306 3307 | ** exactly matches pKey. ** ** *pRes>0 The cursor is left pointing at an entry that ** is larger than pKey. */ int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){ int rc; | < < > | < < < < < | 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 | ** exactly matches pKey. ** ** *pRes>0 The cursor is left pointing at an entry that ** is larger than pKey. */ int sqlite3BtreeMoveto(BtCursor *pCur, const void *pKey, i64 nKey, int *pRes){ int rc; rc = moveToRoot(pCur); if( rc ) return rc; assert( pCur->pPage ); assert( pCur->pPage->isInit ); if( pCur->eState==CURSOR_INVALID ){ *pRes = -1; assert( pCur->pPage->nCell==0 ); return SQLITE_OK; } for(;;){ int lwr, upr; Pgno chldPg; MemPage *pPage = pCur->pPage; int c = -1; /* pRes return if table is empty must be -1 */ lwr = 0; upr = pPage->nCell-1; if( !pPage->intKey && pKey==0 ){ return SQLITE_CORRUPT_BKPT; } pCur->idx = upr; if( lwr<=upr ) for(;;){ void *pCellKey; i64 nCellKey; pCur->info.nSize = 0; if( pPage->intKey ){ u8 *pCell; pCell = findCell(pPage, pCur->idx) + pPage->childPtrSize; if( pPage->hasData ){ u32 dummy; pCell += getVarint32(pCell, &dummy); } getVarint(pCell, (u64 *)&nCellKey); if( nCellKey<nKey ){ c = -1; }else if( nCellKey>nKey ){ c = +1; }else{ c = 0; } }else{ int available; pCellKey = (void *)fetchPayload(pCur, &available, 0); nCellKey = pCur->info.nKey; |
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3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 | } } if( c<0 ){ lwr = pCur->idx+1; }else{ upr = pCur->idx-1; } } assert( lwr==upr+1 ); assert( pPage->isInit ); if( pPage->leaf ){ chldPg = 0; }else if( lwr>=pPage->nCell ){ chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]); | > > > > | 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 | } } if( c<0 ){ lwr = pCur->idx+1; }else{ upr = pCur->idx-1; } if( lwr>upr ){ break; } pCur->idx = (lwr+upr)/2; } assert( lwr==upr+1 ); assert( pPage->isInit ); if( pPage->leaf ){ chldPg = 0; }else if( lwr>=pPage->nCell ){ chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]); |
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