Message-ID: <f3e61e27-19d0-5e40-3eb2-53282fa0532a@gmail.com>
Date: Sun, 31 Mar 2024 12:00:00 +0300
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Subject: Re: ALTER TABLE SET ACCESS METHOD on partitioned tables
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To: Alvaro Herrera <alvherre@alvh.no-ip.org>,
 Justin Pryzby <pryzby@telsasoft.com>
Cc: Michael Paquier <michael@paquier.xyz>,
 Peter Eisentraut <peter@eisentraut.org>,
 Soumyadeep Chakraborty <soumyadeep2007@gmail.com>,
 Zhihong Yu <zyu@yugabyte.com>, pgsql-hackers@postgresql.org,
 Ashwin Agrawal <ashwinstar@gmail.com>, vanjared@vmware.com
References: <202403281558.xk5pgf7ur3dq@alvherre.pgsql>
From: Alexander Lakhin <exclusion@gmail.com>
In-Reply-To: <202403281558.xk5pgf7ur3dq@alvherre.pgsql>
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Hello Alvaro,

28.03.2024 18:58, Alvaro Herrera wrote:
> Grumble.  I don't like initialization at declare time, so far from the
> code that depends on the value.  But the alternative would have been to
> assign right where this blocks starts, an additional line.  I pushed it
> like you had it.

I've stumbled upon a test failure caused by the test query added in that
commit:
--- .../src/test/regress/expected/create_am.out      2024-03-28 12:14:11.700764888 -0400
+++ .../src/test/recovery/tmp_check/results/create_am.out 2024-03-31 03:10:28.172244122 -0400
@@ -549,7 +549,10 @@
  ERROR:  access method "btree" is not of type TABLE
  -- Other weird invalid cases that cause problems
  CREATE FOREIGN TABLE fp PARTITION OF pg_am DEFAULT SERVER x;
-ERROR:  "pg_am" is not partitioned
+ERROR:  deadlock detected
+DETAIL:  Process 3076180 waits for AccessShareLock on relation 1259 of database 16386; blocked by process 3076181.
+Process 3076181 waits for AccessShareLock on relation 2601 of database 16386; blocked by process 3076180.
+HINT:  See server log for query details.
  -- Drop table access method, which fails as objects depends on it
  DROP ACCESS METHOD heap2;
  ERROR:  cannot drop access method heap2 because other objects depend on it

027_stream_regress_primary.log contains:
2024-03-31 03:10:26.728 EDT [3076181] pg_regress/vacuum LOG: statement: VACUUM FULL pg_class;
...
2024-03-31 03:10:26.797 EDT [3076180] pg_regress/create_am LOG: statement: CREATE FOREIGN TABLE fp PARTITION OF pg_am 
DEFAULT SERVER x;
...
2024-03-31 03:10:28.183 EDT [3076181] pg_regress/vacuum LOG: statement: VACUUM FULL pg_database;

This simple demo confirms the issue:
for ((i=1;i<=20;i++)); do
echo "iteration $i"
echo "VACUUM FULL pg_class;" | psql >psql-1.log &
echo "CREATE FOREIGN TABLE fp PARTITION OF pg_am DEFAULT SERVER x;" | psql >psql-2.log &
wait
done

...
iteration 15
ERROR:  "pg_am" is not partitioned
iteration 16
ERROR:  deadlock detected
DETAIL:  Process 2556377 waits for AccessShareLock on relation 1259 of database 16384; blocked by process 2556378.
Process 2556378 waits for AccessShareLock on relation 2601 of database 16384; blocked by process 2556377.
HINT:  See server log for query details.
...

Best regards,
Alexander