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Overview
| Comment: | In the balance_nonroot() routine, protect the values in aPgno[] array from change during the page sort, so that aPgno[] can be used to avoid unnecessary pointer-map updates for auto_vacuum databases. |
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| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
69c3924fe834a78d4a8d86833626bf5f |
| User & Date: | drh 2014-10-31 00:05:23.983 |
Context
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2014-10-31
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| 02:51 | Remove an unnecessary branch from balance_nonroot(). (check-in: 9fc7c88e3f user: drh tags: trunk) | |
| 00:05 | In the balance_nonroot() routine, protect the values in aPgno[] array from change during the page sort, so that aPgno[] can be used to avoid unnecessary pointer-map updates for auto_vacuum databases. (check-in: 69c3924fe8 user: drh tags: trunk) | |
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2014-10-30
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| 23:14 | Improvements to the wording of some comments. Reinstate an assert() that is only true for non-corrupt database files by adding an "|| CORRUPT_DB" term. (check-in: 67adb44838 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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6529 6530 6531 6532 6533 6534 6535 6536 6537 6538 6539 6540 6541 6542 | int szNew[NB+2]; /* Combined size of cells placed on i-th page */ u8 **apCell = 0; /* All cells begin balanced */ u16 *szCell; /* Local size of all cells in apCell[] */ u8 *aSpace1; /* Space for copies of dividers cells */ Pgno pgno; /* Temp var to store a page number in */ u8 abDone[NB+2]; /* True after i'th new page is populated */ Pgno aPgno[NB+2]; /* Page numbers of new pages before shuffling */ u16 aPgFlags[NB+2]; /* flags field of new pages before shuffling */ memset(abDone, 0, sizeof(abDone)); pBt = pParent->pBt; assert( sqlite3_mutex_held(pBt->mutex) ); assert( sqlite3PagerIswriteable(pParent->pDbPage) ); | > | 6529 6530 6531 6532 6533 6534 6535 6536 6537 6538 6539 6540 6541 6542 6543 | int szNew[NB+2]; /* Combined size of cells placed on i-th page */ u8 **apCell = 0; /* All cells begin balanced */ u16 *szCell; /* Local size of all cells in apCell[] */ u8 *aSpace1; /* Space for copies of dividers cells */ Pgno pgno; /* Temp var to store a page number in */ u8 abDone[NB+2]; /* True after i'th new page is populated */ Pgno aPgno[NB+2]; /* Page numbers of new pages before shuffling */ Pgno aPgOrder[NB+2]; /* Copy of aPgno[] used for sorting pages */ u16 aPgFlags[NB+2]; /* flags field of new pages before shuffling */ memset(abDone, 0, sizeof(abDone)); pBt = pParent->pBt; assert( sqlite3_mutex_held(pBt->mutex) ); assert( sqlite3PagerIswriteable(pParent->pDbPage) ); |
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6855 6856 6857 6858 6859 6860 6861 |
** An O(n^2) insertion sort algorithm is used, but since n is never more
** than (NB+2) (a small constant), that should not be a problem.
**
** When NB==3, this one optimization makes the database about 25% faster
** for large insertions and deletions.
*/
for(i=0; i<nNew; i++){
| | | | | | 6856 6857 6858 6859 6860 6861 6862 6863 6864 6865 6866 6867 6868 6869 6870 6871 6872 6873 6874 6875 6876 6877 6878 6879 6880 6881 6882 6883 6884 6885 6886 6887 6888 6889 6890 6891 6892 6893 |
** An O(n^2) insertion sort algorithm is used, but since n is never more
** than (NB+2) (a small constant), that should not be a problem.
**
** When NB==3, this one optimization makes the database about 25% faster
** for large insertions and deletions.
*/
for(i=0; i<nNew; i++){
aPgOrder[i] = aPgno[i] = apNew[i]->pgno;
aPgFlags[i] = apNew[i]->pDbPage->flags;
for(j=0; j<i; j++){
if( aPgno[j]==aPgno[i] ){
/* This branch is taken if the set of sibling pages somehow contains
** duplicate entries. This can happen if the database is corrupt.
** It would be simpler to detect this as part of the loop below, but
** we do the detection here in order to avoid populating the pager
** cache with two separate objects associated with the same
** page number. */
assert( CORRUPT_DB );
rc = SQLITE_CORRUPT_BKPT;
goto balance_cleanup;
}
}
}
for(i=0; i<nNew; i++){
int iBest = 0; /* aPgno[] index of page number to use */
Pgno pgno; /* Page number to use */
for(j=1; j<nNew; j++){
if( aPgOrder[j]<aPgOrder[iBest] ) iBest = j;
}
pgno = aPgOrder[iBest];
aPgOrder[iBest] = 0xffffffff;
if( iBest!=i ){
if( iBest>i ){
sqlite3PagerRekey(apNew[iBest]->pDbPage, pBt->nPage+iBest+1, 0);
}
sqlite3PagerRekey(apNew[i]->pDbPage, pgno, aPgFlags[iBest]);
apNew[i]->pgno = pgno;
}
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