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Overview
Comment: | Small performance increase and size decrease in the btreeInitPage() routine. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
6f415833e0554706dcf04f68ecba4ca2 |
User & Date: | drh 2017-05-25 21:35:56.813 |
Context
2017-05-27
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22:42 | Smaller and faster vdbeSorterCompareText(). (check-in: 542dc4c5eb user: drh tags: trunk) | |
2017-05-25
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21:35 | Small performance increase and size decrease in the btreeInitPage() routine. (check-in: 6f415833e0 user: drh tags: trunk) | |
17:27 | Merge the LEFT JOIN query flattener fixes from 3.19.2. (check-in: 6513e4a121 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 | ** Return SQLITE_OK on success. If we see that the page does ** not contain a well-formed database page, then return ** SQLITE_CORRUPT. Note that a return of SQLITE_OK does not ** guarantee that the page is well-formed. It only shows that ** we failed to detect any corruption. */ static int btreeInitPage(MemPage *pPage){ assert( pPage->pBt!=0 ); assert( pPage->pBt->db!=0 ); assert( sqlite3_mutex_held(pPage->pBt->mutex) ); assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) ); assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) ); assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) ); | > > > > > > > > > > < | < < < < < < < < < < | < | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | < | 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 | ** Return SQLITE_OK on success. If we see that the page does ** not contain a well-formed database page, then return ** SQLITE_CORRUPT. Note that a return of SQLITE_OK does not ** guarantee that the page is well-formed. It only shows that ** we failed to detect any corruption. */ static int btreeInitPage(MemPage *pPage){ int pc; /* Address of a freeblock within pPage->aData[] */ u8 hdr; /* Offset to beginning of page header */ u8 *data; /* Equal to pPage->aData */ BtShared *pBt; /* The main btree structure */ int usableSize; /* Amount of usable space on each page */ u16 cellOffset; /* Offset from start of page to first cell pointer */ int nFree; /* Number of unused bytes on the page */ int top; /* First byte of the cell content area */ int iCellFirst; /* First allowable cell or freeblock offset */ int iCellLast; /* Last possible cell or freeblock offset */ assert( pPage->pBt!=0 ); assert( pPage->pBt->db!=0 ); assert( sqlite3_mutex_held(pPage->pBt->mutex) ); assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) ); assert( pPage == sqlite3PagerGetExtra(pPage->pDbPage) ); assert( pPage->aData == sqlite3PagerGetData(pPage->pDbPage) ); assert( pPage->isInit==0 ); pBt = pPage->pBt; hdr = pPage->hdrOffset; data = pPage->aData; /* EVIDENCE-OF: R-28594-02890 The one-byte flag at offset 0 indicating ** the b-tree page type. */ if( decodeFlags(pPage, data[hdr]) ) return SQLITE_CORRUPT_BKPT; assert( pBt->pageSize>=512 && pBt->pageSize<=65536 ); pPage->maskPage = (u16)(pBt->pageSize - 1); pPage->nOverflow = 0; usableSize = pBt->usableSize; pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize; pPage->aDataEnd = &data[usableSize]; pPage->aCellIdx = &data[cellOffset]; pPage->aDataOfst = &data[pPage->childPtrSize]; /* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates ** the start of the cell content area. A zero value for this integer is ** interpreted as 65536. */ top = get2byteNotZero(&data[hdr+5]); /* EVIDENCE-OF: R-37002-32774 The two-byte integer at offset 3 gives the ** number of cells on the page. */ pPage->nCell = get2byte(&data[hdr+3]); if( pPage->nCell>MX_CELL(pBt) ){ /* To many cells for a single page. The page must be corrupt */ return SQLITE_CORRUPT_BKPT; } testcase( pPage->nCell==MX_CELL(pBt) ); /* EVIDENCE-OF: R-24089-57979 If a page contains no cells (which is only ** possible for a root page of a table that contains no rows) then the ** offset to the cell content area will equal the page size minus the ** bytes of reserved space. */ assert( pPage->nCell>0 || top==usableSize || CORRUPT_DB ); /* A malformed database page might cause us to read past the end ** of page when parsing a cell. ** ** The following block of code checks early to see if a cell extends ** past the end of a page boundary and causes SQLITE_CORRUPT to be ** returned if it does. */ iCellFirst = cellOffset + 2*pPage->nCell; iCellLast = usableSize - 4; if( pBt->db->flags & SQLITE_CellSizeCk ){ int i; /* Index into the cell pointer array */ int sz; /* Size of a cell */ if( !pPage->leaf ) iCellLast--; for(i=0; i<pPage->nCell; i++){ pc = get2byteAligned(&data[cellOffset+i*2]); testcase( pc==iCellFirst ); testcase( pc==iCellLast ); if( pc<iCellFirst || pc>iCellLast ){ return SQLITE_CORRUPT_BKPT; } sz = pPage->xCellSize(pPage, &data[pc]); testcase( pc+sz==usableSize ); if( pc+sz>usableSize ){ return SQLITE_CORRUPT_BKPT; } } if( !pPage->leaf ) iCellLast++; } /* Compute the total free space on the page ** EVIDENCE-OF: R-23588-34450 The two-byte integer at offset 1 gives the ** start of the first freeblock on the page, or is zero if there are no ** freeblocks. */ pc = get2byte(&data[hdr+1]); nFree = data[hdr+7] + top; /* Init nFree to non-freeblock free space */ if( pc>0 ){ u32 next, size; if( pc<iCellFirst ){ /* EVIDENCE-OF: R-55530-52930 In a well-formed b-tree page, there will ** always be at least one cell before the first freeblock. */ return SQLITE_CORRUPT_BKPT; } while( 1 ){ if( pc>iCellLast ){ return SQLITE_CORRUPT_BKPT; /* Freeblock off the end of the page */ } next = get2byte(&data[pc]); size = get2byte(&data[pc+2]); nFree = nFree + size; if( next<=pc+size+3 ) break; pc = next; } if( next>0 ){ return SQLITE_CORRUPT_BKPT; /* Freeblock not in ascending order */ } if( pc+size>(unsigned int)usableSize ){ return SQLITE_CORRUPT_BKPT; /* Last freeblock extends past page end */ } } /* At this point, nFree contains the sum of the offset to the start ** of the cell-content area plus the number of free bytes within ** the cell-content area. If this is greater than the usable-size ** of the page, then the page must be corrupted. This check also ** serves to verify that the offset to the start of the cell-content ** area, according to the page header, lies within the page. */ if( nFree>usableSize ){ return SQLITE_CORRUPT_BKPT; } pPage->nFree = (u16)(nFree - iCellFirst); pPage->isInit = 1; return SQLITE_OK; } /* ** Set up a raw page so that it looks like a database page holding ** no entries. */ |
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3356 3357 3358 3359 3360 3361 3362 | int i; /* Counter variable */ int nCell; /* Number of cells in page pPage */ int rc; /* Return code */ BtShared *pBt = pPage->pBt; Pgno pgno = pPage->pgno; assert( sqlite3_mutex_held(pPage->pBt->mutex) ); | | | 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 | int i; /* Counter variable */ int nCell; /* Number of cells in page pPage */ int rc; /* Return code */ BtShared *pBt = pPage->pBt; Pgno pgno = pPage->pgno; assert( sqlite3_mutex_held(pPage->pBt->mutex) ); rc = pPage->isInit ? SQLITE_OK : btreeInitPage(pPage); if( rc!=SQLITE_OK ) return rc; nCell = pPage->nCell; for(i=0; i<nCell; i++){ u8 *pCell = findCell(pPage, i); ptrmapPutOvflPtr(pPage, pCell, &rc); |
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3407 3408 3409 3410 3411 3412 3413 | } put4byte(pPage->aData, iTo); }else{ int i; int nCell; int rc; | | | 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 | } put4byte(pPage->aData, iTo); }else{ int i; int nCell; int rc; rc = pPage->isInit ? SQLITE_OK : btreeInitPage(pPage); if( rc ) return rc; nCell = pPage->nCell; for(i=0; i<nCell; i++){ u8 *pCell = findCell(pPage, i); if( eType==PTRMAP_OVERFLOW1 ){ CellInfo info; |
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