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Disable the PagerDontWrite() optimization for temp tables. It can cause database corruption if a page passed to PagerDontWrite() is dirty at the start of a transaction that is subsequently rolled back.

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FossilOrigin-Name: 6341ab2ffef298ca16b323358afbea4a4c1fb0e1
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dan
2016-05-04 11:28:03 +00:00
parent 12b35ea980
commit c88ae52d86
4 changed files with 93 additions and 9 deletions
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8
src/pager.c
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@@ -6008,10 +6008,16 @@ int sqlite3PagerIswriteable(DbPage *pPg){
**
** Tests show that this optimization can quadruple the speed of large
** DELETE operations.
**
** This optimization cannot be used with a temp-file, as the page may
** have been dirty at the start of the transaction. In that case, if
** memory pressure forces page pPg out of the cache, the data does need
** to be written out to disk so that it may be read back in if the
** current transaction is rolled back.
*/
void sqlite3PagerDontWrite(PgHdr *pPg){
Pager *pPager = pPg->pPager;
if( (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
if( !pPager->tempFile && (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
pPg->flags |= PGHDR_DONT_WRITE;