diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtpage.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtpage.c | 54 |
1 files changed, 42 insertions, 12 deletions
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c index 5e9e7b9270c..25fdcd289c8 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 1.123 2010/07/06 19:18:55 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.124 2010/08/29 19:33:14 tgl Exp $ * * NOTES * Postgres btree pages look like ordinary relation pages. The opaque @@ -1175,6 +1175,13 @@ _bt_pagedel(Relation rel, Buffer buf, BTStack stack) */ rightsib = opaque->btpo_next; rbuf = _bt_getbuf(rel, rightsib, BT_WRITE); + page = BufferGetPage(rbuf); + opaque = (BTPageOpaque) PageGetSpecialPointer(page); + if (opaque->btpo_prev != target) + elog(ERROR, "right sibling's left-link doesn't match: " + "block %u links to %u instead of expected %u in index \"%s\"", + rightsib, opaque->btpo_prev, target, + RelationGetRelationName(rel)); /* * Next find and write-lock the current parent of the target page. This is @@ -1253,6 +1260,38 @@ _bt_pagedel(Relation rel, Buffer buf, BTStack stack) } /* + * Check that the parent-page index items we're about to delete/overwrite + * contain what we expect. This can fail if the index has become + * corrupt for some reason. We want to throw any error before entering + * the critical section --- otherwise it'd be a PANIC. + * + * The test on the target item is just an Assert because _bt_getstackbuf + * should have guaranteed it has the expected contents. The test on the + * next-child downlink is known to sometimes fail in the field, though. + */ + page = BufferGetPage(pbuf); + opaque = (BTPageOpaque) PageGetSpecialPointer(page); + +#ifdef USE_ASSERT_CHECKING + itemid = PageGetItemId(page, poffset); + itup = (IndexTuple) PageGetItem(page, itemid); + Assert(ItemPointerGetBlockNumber(&(itup->t_tid)) == target); +#endif + + if (!parent_half_dead) + { + OffsetNumber nextoffset; + + nextoffset = OffsetNumberNext(poffset); + itemid = PageGetItemId(page, nextoffset); + itup = (IndexTuple) PageGetItem(page, itemid); + if (ItemPointerGetBlockNumber(&(itup->t_tid)) != rightsib) + elog(ERROR, "right sibling %u of block %u is not next child %u of block %u in index \"%s\"", + rightsib, target, ItemPointerGetBlockNumber(&(itup->t_tid)), + parent, RelationGetRelationName(rel)); + } + + /* * Here we begin doing the deletion. */ @@ -1265,8 +1304,6 @@ _bt_pagedel(Relation rel, Buffer buf, BTStack stack) * to copy the right sibling's downlink over the target downlink, and then * delete the following item. */ - page = BufferGetPage(pbuf); - opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (parent_half_dead) { PageIndexTupleDelete(page, poffset); @@ -1278,23 +1315,16 @@ _bt_pagedel(Relation rel, Buffer buf, BTStack stack) itemid = PageGetItemId(page, poffset); itup = (IndexTuple) PageGetItem(page, itemid); - Assert(ItemPointerGetBlockNumber(&(itup->t_tid)) == target); ItemPointerSet(&(itup->t_tid), rightsib, P_HIKEY); nextoffset = OffsetNumberNext(poffset); - /* This part is just for double-checking */ - itemid = PageGetItemId(page, nextoffset); - itup = (IndexTuple) PageGetItem(page, itemid); - if (ItemPointerGetBlockNumber(&(itup->t_tid)) != rightsib) - elog(PANIC, "right sibling %u of block %u is not next child of %u in index \"%s\"", - rightsib, target, BufferGetBlockNumber(pbuf), - RelationGetRelationName(rel)); PageIndexTupleDelete(page, nextoffset); } /* * Update siblings' side-links. Note the target page's side-links will - * continue to point to the siblings. + * continue to point to the siblings. Asserts here are just rechecking + * things we already verified above. */ if (BufferIsValid(lbuf)) { |