Date: Mon, 17 Aug 2020 16:21:01 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: [BUG] Error in BRIN summarization
Message-ID: <20200817202101.GA3895@alvherre.pgsql>
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On 2020-Aug-17, Alvaro Herrera wrote:

> Hmm, the only explanation I can see for this is that autovacuum managed
> to summarize the range before the test script did it.  So the solution
> would simply be to disable autovacuum for the table across the whole
> script.
> 
> I'm running the scripts and dependencies to verify that fix, but under
> CLOBBER_CACHE_ALWAYS that takes quite a bit.

I ran a subset of tests a few times, but was unable to reproduce the
problem.  I'll just push this to all branches and hope for the best.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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 filename="0001-Disable-autovacuum-for-BRIN-test-table.patch"

From 6e70443edacfc86674995c0c10ade0aec7a4fddf Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Mon, 17 Aug 2020 16:20:06 -0400
Subject: [PATCH] Disable autovacuum for BRIN test table

This should improve stability in the tests.

Per buildfarm member hyrax (CLOBBER_CACHE_ALWAYS) via Tom Lane.

Discussion: https://postgr.es/m/871534.1597503261@sss.pgh.pa.us
---
 src/test/regress/expected/brin.out | 2 +-
 src/test/regress/sql/brin.sql      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/test/regress/expected/brin.out b/src/test/regress/expected/brin.out
index 0b14c73fc6..18403498df 100644
--- a/src/test/regress/expected/brin.out
+++ b/src/test/regress/expected/brin.out
@@ -26,7 +26,7 @@ CREATE TABLE brintest (byteacol bytea,
 	int4rangecol int4range,
 	lsncol pg_lsn,
 	boxcol box
-) WITH (fillfactor=10);
+) WITH (fillfactor=10, autovacuum_enabled=off);
 INSERT INTO brintest SELECT
 	repeat(stringu1, 8)::bytea,
 	substr(stringu1, 1, 1)::"char",
diff --git a/src/test/regress/sql/brin.sql b/src/test/regress/sql/brin.sql
index 1289e76ecb..d1a82474f3 100644
--- a/src/test/regress/sql/brin.sql
+++ b/src/test/regress/sql/brin.sql
@@ -26,7 +26,7 @@ CREATE TABLE brintest (byteacol bytea,
 	int4rangecol int4range,
 	lsncol pg_lsn,
 	boxcol box
-) WITH (fillfactor=10);
+) WITH (fillfactor=10, autovacuum_enabled=off);
 
 INSERT INTO brintest SELECT
 	repeat(stringu1, 8)::bytea,
-- 
2.20.1


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