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commit    8782ea2f36a2468e08c227c8d7907a5a1a9f5e32
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Wed Aug 12 19:33:36 2020 +0000
First released in: 14.0, 9.5.24, 9.6.20, 10.15, 11.10, 12.5, 13.0

    BRIN: Handle concurrent desummarization properly
    
    If a page range is desummarized at just the right time concurrently with
    an index walk, BRIN would raise an error indicating index corruption.
    This is scary and unhelpful; silently returning that the page range is
    not summarized is sufficient reaction.
    
    This bug was introduced by commit 975ad4e602ff as additional protection
    against a bug whose actual fix was elsewhere.  Backpatch equally.
    
    Reported-By: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
    Diagnosed-By: Alexander Lakhin <exclusion@gmail.com>
    Discussion: https://postgr.es/m/2588667e-d07d-7e10-74e2-7e1e46194491@postgrespro.ru
    Backpatch: 9.5 - master


 src/backend/access/brin/brin_revmap.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/brin/brin_revmap.c b/src/backend/access/brin/brin_revmap.c
index e8b8308f82e..35746714a7c 100644
--- a/src/backend/access/brin/brin_revmap.c
+++ b/src/backend/access/brin/brin_revmap.c
@@ -282,10 +282,17 @@ brinGetTupleForHeapBlock(BrinRevmap *revmap, BlockNumber heapBlk,
 		/* If we land on a revmap page, start over */
 		if (BRIN_IS_REGULAR_PAGE(page))
 		{
+			/*
+			 * If the offset number is greater than what's in the page, it's
+			 * possible that the range was desummarized concurrently. Just
+			 * return NULL to handle that case.
+			 */
 			if (*off > PageGetMaxOffsetNumber(page))
-				ereport(ERROR,
-						(errcode(ERRCODE_INDEX_CORRUPTED),
-						 errmsg_internal("corrupted BRIN index: inconsistent range map")));
+			{
+				LockBuffer(*buf, BUFFER_LOCK_UNLOCK);
+				return NULL;
+			}
+
 			lp = PageGetItemId(page, *off);
 			if (ItemIdIsUsed(lp))
 			{


[parent: 1754a71986e8]