Postgresql crash (signal 11). keywords: distinct, subselect, union

From: "Magnus Naeslund(f)" <mag(at)fbab(dot)net>
To: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Postgresql crash (signal 11). keywords: distinct, subselect, union
Date: 2006-02-13 14:04:38
Message-ID: 43F091F6.60107@fbab.net
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I just wanted to check if this has been fixed in any recent v8.1.x
release, since I'm using v8.1.0 now.

Backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x08152448 in qual_is_pushdown_safe ()
(gdb) bt
#0 0x08152448 in qual_is_pushdown_safe ()
#1 0x08151e47 in set_subquery_pathlist ()
#2 0x08151a3c in set_base_rel_pathlists ()
#3 0x08151960 in make_one_rel ()
#4 0x0815dcaf in query_planner ()
#5 0x0815ea19 in grouping_planner ()
#6 0x0815e2e4 in subquery_planner ()
#7 0x0815dfaa in planner ()
#8 0x08197b7c in pg_plan_query ()
#9 0x08197c39 in pg_plan_queries ()
#10 0x08197e3d in exec_simple_query ()
#11 0x0819a6fe in PostgresMain ()
#12 0x08176356 in BackendRun ()
#13 0x08175c77 in BackendStartup ()
#14 0x08173ee2 in ServerLoop ()
#15 0x08173723 in PostmasterMain ()
#16 0x08139f90 in main ()
#17 0x400dc14f in __libc_start_main () from /lib/libc.so.6

The crashing query is below, if I remove the "not is null" test it
doesn't crash.

How to reproduce:

create table snicker_whatever(
id SERIAL primary key
);

create table snicker (
id SERIAL primary key,
name_singular text not null unique,
name_plural text not null unique
);

create table snicker_group (
id SERIAL primary key,
title varchar(64) not null,
snicker_id integer not null references snicker_whatever(id)
);

create table snicker_group_mapping (
id SERIAL primary key,
snicker_group_id integer not null references snicker_group(id),
snicker_id integer references snicker(id)
);

SELECT DISTINCT
*
FROM
(
SELECT
vtgm.snicker_id
FROM snicker_group_mapping vtgm
WHERE exists
(
SELECT
*
FROM snicker_group vtg
WHERE vtgm.snicker_group_id = vtg.id
AND lower(vtg.title) ~* 'test'
)
UNION
SELECT
snicker.id
FROM snicker
WHERE lower(snicker.name_singular) ~* 'test'
OR lower(snicker.name_plural) ~* 'test'
) AS vt_id
WHERE vt_id is not null;

Regards,
Magnus

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