From: PG Bug reporting form <noreply@postgresql.org>
To: pgsql-bugs@lists.postgresql.org
Cc: zuming.jiang@inf.ethz.ch
Subject: BUG #18030: Large memory consumption caused by in-clause subqueries
Date: Wed, 19 Jul 2023 08:49:38 +0000
Message-ID: <18030-2a563b7ccc7d6152@postgresql.org> (raw)
The following bug has been logged on the website:
Bug reference: 18030
Logged by: Zuming Jiang
Email address: zuming.jiang@inf.ethz.ch
PostgreSQL version: 16beta2
Operating system: Ubuntu 20.04
Description:
My fuzzer finds a potential bug in Postgres, which consumes lots of memory
and finally kills the Postgres server on my machine.
--- Test case ---
create table t0 (vkey int4, c0 int4, c5 text);
create table t4 (c28 text);
insert into t0 values (16, -32, 'hCV');
insert into t0 values (18, 59, '#;y=+');
insert into t0 values (33, 16, 'xyOG;');
insert into t0 values (40, -38, 'I|f');
insert into t0 values (44, -58, 'F');
insert into t0 values (47, 88, 'I');
insert into t0 values (52, -0, 'BGrK');
insert into t0 values (53, -7, ' T*k');
insert into t4 values ('E');
insert into t4 values ('l&^');
insert into t4 values ('');
insert into t4 values ('Z@~');
insert into t4 values (null::text);
insert into t4 values ('ngL@');
insert into t4 values (null::text);
insert into t4 values ('M+');
select * from t0
where
lpad(t0.c5, int4mi(t0.vkey, t0.c0 << t0.c0)) in (
select
ref_0.c28 as c_0
from
t4 as ref_0
where t0.vkey >= 0)
---
--- Expected behavior ---
The test case should be executed successfully.
--- Actual behavior ---
Postgres server consumes lots of memories and finally gets killed
--- Postgres version ---
Github commit: 8fab4b34801331f1c59352cb0a248be436b60aef
Version: PostgreSQL 17devel on x86_64-pc-linux-gnu, compiled by clang
version 10.0.0-4ubuntu1 , 64-bit
--- Platform information ---
Platform: Ubuntu 20.04
Kernel: Linux 5.4.0-147-generic
--- Note ---
After I replace "where t0.vkey >= 0" with "where true" (which does not
change semantics because t0.vkey is always larger than 0), the SELECT query
is much faster and consumes much less memories.
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To: pgsql-bugs@postgresql.org
Cc: noreply@postgresql.org, pgsql-bugs@lists.postgresql.org, zuming.jiang@inf.ethz.ch
Subject: Re: BUG #18030: Large memory consumption caused by in-clause subqueries
In-Reply-To: <18030-2a563b7ccc7d6152@postgresql.org>
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