From dd951dc34a2ecde28cd8d686cd06de1d21f474a0 Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Thu, 13 Dec 2018 06:12:31 +0300 Subject: Prevent GIN deleted pages from being reclaimed too early When GIN vacuum deletes a posting tree page, it assumes that no concurrent searchers can access it, thanks to ginStepRight() locking two pages at once. However, since 9.4 searches can skip parts of posting trees descending from the root. That leads to the risk that page is deleted and reclaimed before concurrent search can access it. This commit prevents the risk of above by waiting for every transaction, which might wait to reference this page, to finish. Due to binary compatibility we can't change GinPageOpaqueData to store corresponding transaction id. Instead we reuse page header pd_prune_xid field, which is unused in index pages. Discussion: https://postgr.es/m/31a702a.14dd.166c1366ac1.Coremail.chjischj%40163.com Author: Andrey Borodin, Alexander Korotkov Reviewed-by: Alexander Korotkov Backpatch-through: 9.4 --- src/backend/access/gin/ginxlog.c | 1 + 1 file changed, 1 insertion(+) (limited to 'src/backend/access/gin/ginxlog.c') diff --git a/src/backend/access/gin/ginxlog.c b/src/backend/access/gin/ginxlog.c index b626a219dec..b84ecf2ab15 100644 --- a/src/backend/access/gin/ginxlog.c +++ b/src/backend/access/gin/ginxlog.c @@ -531,6 +531,7 @@ ginRedoDeletePage(XLogReaderState *record) page = BufferGetPage(dbuffer); Assert(GinPageIsData(page)); GinPageGetOpaque(page)->flags = GIN_DELETED; + GinPageSetDeleteXid(page, data->deleteXid); PageSetLSN(page, lsn); MarkBufferDirty(dbuffer); } -- cgit v1.2.3