From 08bff295a7e7ac66a35f42e92e97782b9af64cdc Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas
Date: Fri, 29 Aug 2014 14:19:34 +0300
Subject: Fix bug in compressed GIN data leaf page splitting code.

The list of posting lists it's dealing with can contain placeholders for
deleted posting lists. The placeholders are kept around so that they can
be WAL-logged, but we must be careful to not try to access them.

This fixes bug #11280, reported by Mårten Svantesson. Backpatch to 9.4,
where the compressed data leaf page code was added.
---
 src/backend/access/gin/gindatapage.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

(limited to 'src')

diff --git a/src/backend/access/gin/gindatapage.c b/src/backend/access/gin/gindatapage.c
index 272a9ca7c09..0ea4f3fe284 100644
--- a/src/backend/access/gin/gindatapage.c
+++ b/src/backend/access/gin/gindatapage.c
@@ -642,20 +642,24 @@ dataPlaceToPageLeaf(GinBtree btree, Buffer buf, GinBtreeStack *stack,
 			{
 				lastleftinfo = dlist_container(leafSegmentInfo, node, leaf->lastleft);
 
-				segsize = SizeOfGinPostingList(lastleftinfo->seg);
-				if (append)
+				/* ignore deleted segments */
+				if (lastleftinfo->action != GIN_SEGMENT_DELETE)
 				{
-					if ((leaf->lsize - segsize) - (leaf->lsize - segsize) < BLCKSZ / 4)
-						break;
+					segsize = SizeOfGinPostingList(lastleftinfo->seg);
+					if (append)
+					{
+						if ((leaf->lsize - segsize) - (leaf->lsize - segsize) < BLCKSZ / 4)
+							break;
+					}
+					else
+					{
+						if ((leaf->lsize - segsize) - (leaf->rsize + segsize) < 0)
+							break;
+					}
+
+					leaf->lsize -= segsize;
+					leaf->rsize += segsize;
 				}
-				else
-				{
-					if ((leaf->lsize - segsize) - (leaf->rsize + segsize) < 0)
-						break;
-				}
-
-				leaf->lsize -= segsize;
-				leaf->rsize += segsize;
 				leaf->lastleft = dlist_prev_node(&leaf->segments, leaf->lastleft);
 			}
 		}
-- 
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