From 8607fdf0337051ca1da493ded5db15c41da08d66 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Mon, 17 Nov 2014 18:42:04 +0200 Subject: [PATCH] Fix WAL-logging of B-tree "unlink halfdead page" operation. There was some confusion on how to record the case that the operation unlinks the last non-leaf page in the branch being deleted. _bt_unlink_halfdead_page set the "topdead" field in the WAL record to the leaf page, but the redo routine assumed that it would be an invalid block number in that case. This commit fixes _bt_unlink_halfdead_page to do what the redo routine expected. This code is new in 9.4, so backpatch there. --- src/backend/access/nbtree/nbtpage.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c index b71f65de2c1..a7664524580 100644 --- a/src/backend/access/nbtree/nbtpage.c +++ b/src/backend/access/nbtree/nbtpage.c @@ -1565,7 +1565,6 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) int targetlevel; ItemPointer leafhikey; BlockNumber nextchild; - BlockNumber topblkno; page = BufferGetPage(leafbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); @@ -1589,11 +1588,10 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) */ if (ItemPointerIsValid(leafhikey)) { - topblkno = ItemPointerGetBlockNumber(leafhikey); - target = topblkno; + target = ItemPointerGetBlockNumber(leafhikey); /* fetch the block number of the topmost parent's left sibling */ - buf = _bt_getbuf(rel, topblkno, BT_READ); + buf = _bt_getbuf(rel, target, BT_READ); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); leftsib = opaque->btpo_prev; @@ -1607,7 +1605,6 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) } else { - topblkno = InvalidBlockNumber; target = leafblkno; buf = leafbuf; @@ -1692,9 +1689,11 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) elog(ERROR, "half-dead page changed status unexpectedly in block %u of index \"%s\"", target, RelationGetRelationName(rel)); - /* remember the next child down in the branch. */ + /* remember the next non-leaf child down in the branch. */ itemid = PageGetItemId(page, P_FIRSTDATAKEY(opaque)); nextchild = ItemPointerGetBlockNumber(&((IndexTuple) PageGetItem(page, itemid))->t_tid); + if (nextchild == leafblkno) + nextchild = InvalidBlockNumber; } /* @@ -1780,7 +1779,7 @@ _bt_unlink_halfdead_page(Relation rel, Buffer leafbuf, bool *rightsib_empty) */ if (target != leafblkno) { - if (nextchild == leafblkno) + if (nextchild == InvalidBlockNumber) ItemPointerSetInvalid(leafhikey); else ItemPointerSet(leafhikey, nextchild, P_HIKEY); -- 2.39.5