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Overview
Comment: | Simplification to the insertCell() routine in btree.c, resulting in a performance boost and a very small size decrease. It turns out that the extra work involved in sometimes avoiding an memcpy() of the first four bytes of a record takes more time than just unconditionally copying those four bytes. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
66de15580d3c289601e67debfe1edee2 |
User & Date: | drh 2014-10-11 17:22:55.486 |
Context
2014-10-11
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23:31 | Performance optimization and very slight size reduction for OP_Column. (check-in: 869c30e45c user: drh tags: trunk) | |
17:22 | Simplification to the insertCell() routine in btree.c, resulting in a performance boost and a very small size decrease. It turns out that the extra work involved in sometimes avoiding an memcpy() of the first four bytes of a record takes more time than just unconditionally copying those four bytes. (check-in: 66de15580d user: drh tags: trunk) | |
10:52 | Require the SQLITE_ENABLE_RTREE compile-time option in speedtest1.c in order to enable the R-Tree tests. (check-in: 5d29a033b0 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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5841 5842 5843 5844 5845 5846 5847 | ** If the cell content will fit on the page, then put it there. If it ** will not fit, then make a copy of the cell content into pTemp if ** pTemp is not null. Regardless of pTemp, allocate a new entry ** in pPage->apOvfl[] and make it point to the cell content (either ** in pTemp or the original pCell) and also record its index. ** Allocating a new entry in pPage->aCell[] implies that ** pPage->nOverflow is incremented. | < < < < < < | | 5841 5842 5843 5844 5845 5846 5847 5848 5849 5850 5851 5852 5853 5854 5855 5856 5857 5858 5859 5860 5861 5862 5863 5864 5865 5866 5867 5868 5869 5870 5871 5872 5873 5874 5875 5876 5877 5878 5879 5880 5881 5882 5883 5884 5885 5886 5887 5888 | ** If the cell content will fit on the page, then put it there. If it ** will not fit, then make a copy of the cell content into pTemp if ** pTemp is not null. Regardless of pTemp, allocate a new entry ** in pPage->apOvfl[] and make it point to the cell content (either ** in pTemp or the original pCell) and also record its index. ** Allocating a new entry in pPage->aCell[] implies that ** pPage->nOverflow is incremented. */ static void insertCell( MemPage *pPage, /* Page into which we are copying */ int i, /* New cell becomes the i-th cell of the page */ u8 *pCell, /* Content of the new cell */ int sz, /* Bytes of content in pCell */ u8 *pTemp, /* Temp storage space for pCell, if needed */ Pgno iChild, /* If non-zero, replace first 4 bytes with this value */ int *pRC /* Read and write return code from here */ ){ int idx = 0; /* Where to write new cell content in data[] */ int j; /* Loop counter */ int end; /* First byte past the last cell pointer in data[] */ int ins; /* Index in data[] where new cell pointer is inserted */ int cellOffset; /* Address of first cell pointer in data[] */ u8 *data; /* The content of the whole page */ if( *pRC ) return; assert( i>=0 && i<=pPage->nCell+pPage->nOverflow ); assert( MX_CELL(pPage->pBt)<=10921 ); assert( pPage->nCell<=MX_CELL(pPage->pBt) || CORRUPT_DB ); assert( pPage->nOverflow<=ArraySize(pPage->apOvfl) ); assert( ArraySize(pPage->apOvfl)==ArraySize(pPage->aiOvfl) ); assert( sqlite3_mutex_held(pPage->pBt->mutex) ); /* The cell should normally be sized correctly. However, when moving a ** malformed cell from a leaf page to an interior page, if the cell size ** wanted to be less than 4 but got rounded up to 4 on the leaf, then size ** might be less than 8 (leaf-size + pointer) on the interior node. Hence ** the term after the || in the following assert(). */ assert( sz==cellSizePtr(pPage, pCell) || (sz==8 && iChild>0) ); if( pPage->nOverflow || sz+2>pPage->nFree ){ if( pTemp ){ memcpy(pTemp, pCell, sz); pCell = pTemp; } if( iChild ){ put4byte(pCell, iChild); } j = pPage->nOverflow++; assert( j<(int)(sizeof(pPage->apOvfl)/sizeof(pPage->apOvfl[0])) ); |
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5909 5910 5911 5912 5913 5914 5915 | if( rc ){ *pRC = rc; return; } /* The allocateSpace() routine guarantees the following two properties ** if it returns success */ assert( idx >= end+2 ); assert( idx+sz <= (int)pPage->pBt->usableSize ); pPage->nCell++; pPage->nFree -= (u16)(2 + sz); | | | 5903 5904 5905 5906 5907 5908 5909 5910 5911 5912 5913 5914 5915 5916 5917 | if( rc ){ *pRC = rc; return; } /* The allocateSpace() routine guarantees the following two properties ** if it returns success */ assert( idx >= end+2 ); assert( idx+sz <= (int)pPage->pBt->usableSize ); pPage->nCell++; pPage->nFree -= (u16)(2 + sz); memcpy(&data[idx], pCell, sz); if( iChild ){ put4byte(&data[idx], iChild); } memmove(&data[ins+2], &data[ins], end-ins); put2byte(&data[ins], idx); put2byte(&data[pPage->hdrOffset+3], pPage->nCell); #ifndef SQLITE_OMIT_AUTOVACUUM |
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