diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtpage.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtpage.c | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c index 927860030c8..8464d5478f6 100644 --- a/src/backend/access/nbtree/nbtpage.c +++ b/src/backend/access/nbtree/nbtpage.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.88 2005/10/15 02:49:09 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.88.2.1 2005/11/22 18:23:04 momjian Exp $ * * NOTES * Postgres btree pages look like ordinary relation pages. The opaque @@ -440,21 +440,21 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access) * have been re-used between the time the last VACUUM scanned it and * the time the VACUUM made its FSM updates.) * - * In fact, it's worse than that: we can't even assume that it's safe to - * take a lock on the reported page. If somebody else has a lock on - * it, or even worse our own caller does, we could deadlock. (The + * In fact, it's worse than that: we can't even assume that it's safe + * to take a lock on the reported page. If somebody else has a lock + * on it, or even worse our own caller does, we could deadlock. (The * own-caller scenario is actually not improbable. Consider an index * on a serial or timestamp column. Nearly all splits will be at the * rightmost page, so it's entirely likely that _bt_split will call us - * while holding a lock on the page most recently acquired from FSM. - * A VACUUM running concurrently with the previous split could well - * have placed that page back in FSM.) + * while holding a lock on the page most recently acquired from FSM. A + * VACUUM running concurrently with the previous split could well have + * placed that page back in FSM.) * - * To get around that, we ask for only a conditional lock on the reported - * page. If we fail, then someone else is using the page, and we may - * reasonably assume it's not free. (If we happen to be wrong, the - * worst consequence is the page will be lost to use till the next - * VACUUM, which is no big problem.) + * To get around that, we ask for only a conditional lock on the + * reported page. If we fail, then someone else is using the page, + * and we may reasonably assume it's not free. (If we happen to be + * wrong, the worst consequence is the page will be lost to use till + * the next VACUUM, which is no big problem.) */ for (;;) { @@ -803,12 +803,12 @@ _bt_pagedel(Relation rel, Buffer buf, bool vacuum_full) * We have to lock the pages we need to modify in the standard order: * moving right, then up. Else we will deadlock against other writers. * - * So, we need to find and write-lock the current left sibling of the target - * page. The sibling that was current a moment ago could have split, so - * we may have to move right. This search could fail if either the - * sibling or the target page was deleted by someone else meanwhile; if - * so, give up. (Right now, that should never happen, since page deletion - * is only done in VACUUM and there shouldn't be multiple VACUUMs + * So, we need to find and write-lock the current left sibling of the + * target page. The sibling that was current a moment ago could have + * split, so we may have to move right. This search could fail if either + * the sibling or the target page was deleted by someone else meanwhile; + * if so, give up. (Right now, that should never happen, since page + * deletion is only done in VACUUM and there shouldn't be multiple VACUUMs * concurrently on the same table.) */ if (leftsib != P_NONE) |