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Change the name ZERO_DAMAGE to the more descriptive POWERSAFE_OVERWRITE.

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The query parameter used to control this device characteristic is now "psow".

FossilOrigin-Name: 6191c5e45175f5c6040e891843b0725a929d6dd7
This commit is contained in:
drh
2011-12-23 01:04:17 +00:00
parent bec7c97899
commit cb15f35f3b
13 changed files with 137 additions and 117 deletions
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15
src/pager.c
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@@ -2516,20 +2516,21 @@ static int pager_truncate(Pager *pPager, Pgno nPage){
** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
** is greater than MAX_SECTOR_SIZE.
**
** If the file has the SQLITE_IOCAP_ZERO_DAMAGE property, then set the
** effective sector size to its minimum value (512). The purpose of
** If the file has the SQLITE_IOCAP_POWERSAFE_OVERWRITE property, then set
** the effective sector size to its minimum value (512). The purpose of
** pPager->sectorSize is to define the "blast radius" of bytes that
** might change if a crash occurs while writing to a single byte in
** that range. But with ZERO_DAMAGE, the blast radius is zero, so
** we minimize the sector size. For backwards compatibility of the
** rollback journal file format, we cannot reduce the effective sector
** size below 512.
** that range. But with POWERSAFE_OVERWRITE, the blast radius is zero
** (that is what POWERSAFE_OVERWRITE means), so we minimize the sector
** size. For backwards compatibility of the rollback journal file format,
** we cannot reduce the effective sector size below 512.
*/
static void setSectorSize(Pager *pPager){
assert( isOpen(pPager->fd) || pPager->tempFile );
if( pPager->tempFile
|| (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_ZERO_DAMAGE)!=0
|| (sqlite3OsDeviceCharacteristics(pPager->fd) &
SQLITE_IOCAP_POWERSAFE_OVERWRITE)!=0
){
/* Sector size doesn't matter for temporary files. Also, the file
** may not have been opened yet, in which case the OsSectorSize()