diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/commands/vacuum.c | 15 | ||||
| -rw-r--r-- | src/backend/commands/vacuumlazy.c | 4 |
2 files changed, 13 insertions, 6 deletions
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 1e3a420c364..9813183cb95 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -13,7 +13,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.314 2005/09/02 19:02:19 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.315 2005/09/22 17:32:58 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1273,10 +1273,14 @@ scan_heap(VRelStats *vacrelstats, Relation onerel, page = BufferGetPage(buf); /* - * We don't bother to do LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE) - * because we assume that holding exclusive lock on the relation - * will keep other backends from looking at the page. + * Since we are holding exclusive lock on the relation, no other + * backend can be accessing the page; however it is possible that + * the background writer will try to write the page if it's already + * marked dirty. To ensure that invalid data doesn't get written to + * disk, we must take exclusive buffer lock wherever we potentially + * modify pages. */ + LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE); vacpage->blkno = blkno; vacpage->offsets_used = 0; @@ -1297,6 +1301,7 @@ scan_heap(VRelStats *vacrelstats, Relation onerel, vacpagecopy = copy_vac_page(vacpage); vpage_insert(vacuum_pages, vacpagecopy); vpage_insert(fraged_pages, vacpagecopy); + LockBuffer(buf, BUFFER_LOCK_UNLOCK); WriteBuffer(buf); continue; } @@ -1312,6 +1317,7 @@ scan_heap(VRelStats *vacrelstats, Relation onerel, vacpagecopy = copy_vac_page(vacpage); vpage_insert(vacuum_pages, vacpagecopy); vpage_insert(fraged_pages, vacpagecopy); + LockBuffer(buf, BUFFER_LOCK_UNLOCK); ReleaseBuffer(buf); continue; } @@ -1520,6 +1526,7 @@ scan_heap(VRelStats *vacrelstats, Relation onerel, else empty_end_pages = 0; + LockBuffer(buf, BUFFER_LOCK_UNLOCK); if (pgchanged) WriteBuffer(buf); else diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c index f324b726734..88ff2d4da46 100644 --- a/src/backend/commands/vacuumlazy.c +++ b/src/backend/commands/vacuumlazy.c @@ -31,7 +31,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.58 2005/09/02 19:02:20 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.59 2005/09/22 17:32:58 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -299,7 +299,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats, * or temp relation, but it's probably not worth the code space * to check that, since this surely isn't a critical path. * - * Note: the comparable code in vacuum.c need not do all this + * Note: the comparable code in vacuum.c need not worry * because it's got exclusive lock on the whole relation. */ LockBuffer(buf, BUFFER_LOCK_UNLOCK); |