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Overview
Comment: | Another performance tweak: Split the sqlite3BtreeCursorHasMoved() routine into two with the second routine named sqlite3BtreeCursorRestore(). The first now only reports whether or not the cursor has moved and the second tries to restore the cursor. This allows the sqlite3VdbeCursorMoveto() routine to be refactored to avoid stack pointer movements, for a noticable performance gain. |
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Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
ce123b5c592556a8cd38b01fcc91ba76 |
User & Date: | drh 2014-08-22 23:33:03.189 |
Context
2014-08-23
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17:21 | Performance optimization in the applyAffinity() logic inside the VDBE. (check-in: 25f2246be4 user: drh tags: trunk) | |
2014-08-22
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23:33 | Another performance tweak: Split the sqlite3BtreeCursorHasMoved() routine into two with the second routine named sqlite3BtreeCursorRestore(). The first now only reports whether or not the cursor has moved and the second tries to restore the cursor. This allows the sqlite3VdbeCursorMoveto() routine to be refactored to avoid stack pointer movements, for a noticable performance gain. (check-in: ce123b5c59 user: drh tags: trunk) | |
22:26 | Factor the saveAllCursors() routine of btree.c into two separate routines, for a noticable performance improvement. (check-in: 3eb0843903 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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758 759 760 761 762 763 764 | #define restoreCursorPosition(p) \ (p->eState>=CURSOR_REQUIRESEEK ? \ btreeRestoreCursorPosition(p) : \ SQLITE_OK) /* | | > | | > | < | < > > | > > | < > | > | > > > > > > > > | > | < < < | | | | 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 | #define restoreCursorPosition(p) \ (p->eState>=CURSOR_REQUIRESEEK ? \ btreeRestoreCursorPosition(p) : \ SQLITE_OK) /* ** Determine whether or not a cursor has moved from the position where ** it was last placed, or has been invalidated for any other reason. ** Cursors can move when the row they are pointing at is deleted out ** from under them, for example. Cursor might also move if a btree ** is rebalanced. ** ** Calling this routine with a NULL cursor pointer returns false. ** ** Use the separate sqlite3BtreeCursorRestore() routine to restore a cursor ** back to where it ought to be if this routine returns true. */ int sqlite3BtreeCursorHasMoved(BtCursor *pCur){ return pCur && pCur->eState!=CURSOR_VALID; } /* ** This routine restores a cursor back to its original position after it ** has been moved by some outside activity (such as a btree rebalance or ** a row having been deleted out from under the cursor). ** ** On success, the *pDifferentRow parameter is false if the cursor is left ** pointing at exactly the same row. *pDifferntRow is the row the cursor ** was pointing to has been deleted, forcing the cursor to point to some ** nearby row. ** ** This routine should only be called for a cursor that just returned ** TRUE from sqlite3BtreeCursorHasMoved(). */ int sqlite3BtreeCursorRestore(BtCursor *pCur, int *pDifferentRow){ int rc; assert( pCur!=0 ); assert( pCur->eState!=CURSOR_VALID ); rc = restoreCursorPosition(pCur); if( rc ){ *pDifferentRow = 1; return rc; } if( pCur->eState!=CURSOR_VALID || NEVER(pCur->skipNext!=0) ){ *pDifferentRow = 1; }else{ *pDifferentRow = 0; } return SQLITE_OK; } #ifndef SQLITE_OMIT_AUTOVACUUM /* ** Given a page number of a regular database page, return the page |
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Changes to src/btree.h.
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165 166 167 168 169 170 171 | int sqlite3BtreeMovetoUnpacked( BtCursor*, UnpackedRecord *pUnKey, i64 intKey, int bias, int *pRes ); | | > | 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 | int sqlite3BtreeMovetoUnpacked( BtCursor*, UnpackedRecord *pUnKey, i64 intKey, int bias, int *pRes ); int sqlite3BtreeCursorHasMoved(BtCursor*); int sqlite3BtreeCursorRestore(BtCursor*, int*); int sqlite3BtreeDelete(BtCursor*); int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey, const void *pData, int nData, int nZero, int bias, int seekResult); int sqlite3BtreeFirst(BtCursor*, int *pRes); int sqlite3BtreeLast(BtCursor*, int *pRes); int sqlite3BtreeNext(BtCursor*, int *pRes); |
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Changes to src/vdbeaux.c.
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2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 | if( p->pNext ){ p->pNext->pPrev = p->pPrev; } p->magic = VDBE_MAGIC_DEAD; p->db = 0; sqlite3DbFree(db, p); } /* ** Make sure the cursor p is ready to read or write the row to which it ** was last positioned. Return an error code if an OOM fault or I/O error ** prevents us from positioning the cursor to its correct position. ** ** If a MoveTo operation is pending on the given cursor, then do that ** MoveTo now. If no move is pending, check to see if the row has been ** deleted out from under the cursor and if it has, mark the row as ** a NULL row. ** ** If the cursor is already pointing to the correct row and that row has ** not been deleted out from under the cursor, then this routine is a no-op. */ int sqlite3VdbeCursorMoveto(VdbeCursor *p){ if( p->deferredMoveto ){ | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > < < < < < < < < < < < < < | < < < < < < < < | > > | 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 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 | if( p->pNext ){ p->pNext->pPrev = p->pPrev; } p->magic = VDBE_MAGIC_DEAD; p->db = 0; sqlite3DbFree(db, p); } /* ** The cursor "p" has a pending seek operation that has not yet been ** carried out. Seek the cursor now. If an error occurs, return ** the appropriate error code. */ static int SQLITE_NOINLINE handleDeferredMoveto(VdbeCursor *p){ int res, rc; #ifdef SQLITE_TEST extern int sqlite3_search_count; #endif assert( p->deferredMoveto ); assert( p->isTable ); rc = sqlite3BtreeMovetoUnpacked(p->pCursor, 0, p->movetoTarget, 0, &res); if( rc ) return rc; p->lastRowid = p->movetoTarget; if( res!=0 ) return SQLITE_CORRUPT_BKPT; p->rowidIsValid = 1; #ifdef SQLITE_TEST sqlite3_search_count++; #endif p->deferredMoveto = 0; p->cacheStatus = CACHE_STALE; return SQLITE_OK; } /* ** Something has moved cursor "p" out of place. Maybe the row it was ** pointed to was deleted out from under it. Or maybe the btree was ** rebalanced. Whatever the cause, try to restore "p" to the place it ** is suppose to be pointing. If the row was deleted out from under the ** cursor, set the cursor to point to a NULL row. */ static int SQLITE_NOINLINE handleMovedCursor(VdbeCursor *p){ int isDifferentRow, rc; assert( p->pCursor!=0 ); assert( sqlite3BtreeCursorHasMoved(p->pCursor) ); rc = sqlite3BtreeCursorRestore(p->pCursor, &isDifferentRow); p->cacheStatus = CACHE_STALE; if( isDifferentRow ) p->nullRow = 1; return rc; } /* ** Make sure the cursor p is ready to read or write the row to which it ** was last positioned. Return an error code if an OOM fault or I/O error ** prevents us from positioning the cursor to its correct position. ** ** If a MoveTo operation is pending on the given cursor, then do that ** MoveTo now. If no move is pending, check to see if the row has been ** deleted out from under the cursor and if it has, mark the row as ** a NULL row. ** ** If the cursor is already pointing to the correct row and that row has ** not been deleted out from under the cursor, then this routine is a no-op. */ int sqlite3VdbeCursorMoveto(VdbeCursor *p){ if( p->deferredMoveto ){ return handleDeferredMoveto(p); } if( sqlite3BtreeCursorHasMoved(p->pCursor) ){ return handleMovedCursor(p); } return SQLITE_OK; } /* ** The following functions: ** |
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