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Overview
| Comment: | Size and performance optimization in btreeInitPage() in the freeblock validation step. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
57deb1b412e0c328528f2b4d697e326b |
| User & Date: | drh 2016-12-12 01:30:01.538 |
Context
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2016-12-12
| ||
| 01:53 | Updates to the tokenizer for EBCDIC. No changes for standard builds. (check-in: 4fc6580ffa user: drh tags: trunk) | |
| 01:30 | Size and performance optimization in btreeInitPage() in the freeblock validation step. (check-in: 57deb1b412 user: drh tags: trunk) | |
| 00:58 | Change the order of comparison for divider cell overflow in balance non-root to avoid a (harmless) reference to an uninitialized variable. (check-in: f9f2e23bbd user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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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) );
if( !pPage->isInit ){
| | | 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 |
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) );
if( !pPage->isInit ){
u32 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 */
|
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/* 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 */
| | | | < < > > > > | | > | > > > | < > > | < < | 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 |
/* 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>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
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