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Overview
Comment: | Rearrange fields of the BtCursor object so that it is smaller and requires less initialization, for a small performance improvement. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
0ddf5292cc0411ec6fcb7399ecf2904c |
User & Date: | drh 2018-01-24 16:04:21.587 |
Context
2018-01-24
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18:28 | Reorganize spellfix.c to make it easier to edit automatically (e.g. using a script). No changes to functionality. (check-in: 090a64faaa user: dan tags: trunk) | |
16:04 | Rearrange fields of the BtCursor object so that it is smaller and requires less initialization, for a small performance improvement. (check-in: 0ddf5292cc user: drh tags: trunk) | |
15:07 | Add the normalize.c extension. (check-in: 16ebe558d2 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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4341 4342 4343 4344 4345 4346 4347 | ** ** The simple approach here would be to memset() the entire object ** to zero. But it turns out that the apPage[] and aiIdx[] arrays ** do not need to be zeroed and they are large, so we can save a lot ** of run-time by skipping the initialization of those elements. */ void sqlite3BtreeCursorZero(BtCursor *p){ | | | 4341 4342 4343 4344 4345 4346 4347 4348 4349 4350 4351 4352 4353 4354 4355 | ** ** The simple approach here would be to memset() the entire object ** to zero. But it turns out that the apPage[] and aiIdx[] arrays ** do not need to be zeroed and they are large, so we can save a lot ** of run-time by skipping the initialization of those elements. */ void sqlite3BtreeCursorZero(BtCursor *p){ memset(p, 0, offsetof(BtCursor, BTCURSOR_FIRST_UNINIT)); } /* ** Close a cursor. The read lock on the database file is released ** when the last cursor is closed. */ int sqlite3BtreeCloseCursor(BtCursor *pCur){ |
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4664 4665 4666 4667 4668 4669 4670 | ** The aOverflow[] array is sized at one entry for each overflow page ** in the overflow chain. The page number of the first overflow page is ** stored in aOverflow[0], etc. A value of 0 in the aOverflow[] array ** means "not yet known" (the cache is lazily populated). */ if( (pCur->curFlags & BTCF_ValidOvfl)==0 ){ int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize; | | > > < | 4664 4665 4666 4667 4668 4669 4670 4671 4672 4673 4674 4675 4676 4677 4678 4679 4680 4681 4682 4683 4684 4685 4686 | ** The aOverflow[] array is sized at one entry for each overflow page ** in the overflow chain. The page number of the first overflow page is ** stored in aOverflow[0], etc. A value of 0 in the aOverflow[] array ** means "not yet known" (the cache is lazily populated). */ if( (pCur->curFlags & BTCF_ValidOvfl)==0 ){ int nOvfl = (pCur->info.nPayload-pCur->info.nLocal+ovflSize-1)/ovflSize; if( pCur->aOverflow==0 || nOvfl*sizeof(Pgno) > sqlite3MallocSize(pCur->aOverflow) ){ Pgno *aNew = (Pgno*)sqlite3Realloc( pCur->aOverflow, nOvfl*2*sizeof(Pgno) ); if( aNew==0 ){ return SQLITE_NOMEM_BKPT; }else{ pCur->aOverflow = aNew; } } memset(pCur->aOverflow, 0, nOvfl*sizeof(Pgno)); pCur->curFlags |= BTCF_ValidOvfl; }else{ /* If the overflow page-list cache has been allocated and the |
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Changes to src/btreeInt.h.
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499 500 501 502 503 504 505 | ** eState==FAULT: Cursor fault with skipNext as error code. */ struct BtCursor { u8 eState; /* One of the CURSOR_XXX constants (see below) */ u8 curFlags; /* zero or more BTCF_* flags defined below */ u8 curPagerFlags; /* Flags to send to sqlite3PagerGet() */ u8 hints; /* As configured by CursorSetHints() */ | | > < < < < < < < > > > > > > | 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 | ** eState==FAULT: Cursor fault with skipNext as error code. */ struct BtCursor { u8 eState; /* One of the CURSOR_XXX constants (see below) */ u8 curFlags; /* zero or more BTCF_* flags defined below */ u8 curPagerFlags; /* Flags to send to sqlite3PagerGet() */ u8 hints; /* As configured by CursorSetHints() */ int skipNext; /* Prev() is noop if negative. Next() is noop if positive. ** Error code if eState==CURSOR_FAULT */ Btree *pBtree; /* The Btree to which this cursor belongs */ Pgno *aOverflow; /* Cache of overflow page locations */ void *pKey; /* Saved key that was cursor last known position */ /* All fields above are zeroed when the cursor is allocated. See ** sqlite3BtreeCursorZero(). Fields that follow must be manually ** initialized. */ #define BTCURSOR_FIRST_UNINIT pBt /* Name of first uninitialized field */ BtShared *pBt; /* The BtShared this cursor points to */ BtCursor *pNext; /* Forms a linked list of all cursors */ CellInfo info; /* A parse of the cell we are pointing at */ i64 nKey; /* Size of pKey, or last integer key */ Pgno pgnoRoot; /* The root page of this tree */ i8 iPage; /* Index of current page in apPage */ u8 curIntKey; /* Value of apPage[0]->intKey */ u16 ix; /* Current index for apPage[iPage] */ u16 aiIdx[BTCURSOR_MAX_DEPTH-1]; /* Current index in apPage[i] */ struct KeyInfo *pKeyInfo; /* Arg passed to comparison function */ MemPage *pPage; /* Current page */ MemPage *apPage[BTCURSOR_MAX_DEPTH-1]; /* Stack of parents of current page */ |
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