From: PG Bug reporting form <noreply@postgresql.org>
To: pgsql-bugs@lists.postgresql.org
Cc: washwithcare@gmail.com
Subject: BUG #19031: pg_trgm infinite loop on certain cases
Date: Mon, 25 Aug 2025 21:27:04 +0000
Message-ID: <19031-0638148643d25548@postgresql.org> (raw)
The following bug has been logged on the website:
Bug reference: 19031
Logged by: Tim Wood
Email address: washwithcare@gmail.com
PostgreSQL version: 17.6
Operating system: MacOS
Description:
When querying against a column with a gin_trgm_ops index, using <% with a
string without any trigrams followed by a string with trigrams causes what
appears to be an infinite loop, and the query cannot be canceled, and the
process must be restarted in order to kill the long running query.
Simplified use case:
```
create extension if not exists pg_trgm with schema public;
create temp table simple_case (name text);
create index simple_case_name_index on simple_case using gin (name
gin_trgm_ops);
-- generate enough records for the optimizer to choose the index
insert into simple_case (name) select 'two and' || i::text from
generate_series(1, 1000000) as t(i);
select * from simple_case; -- returns normally
explain select * from simple_case where (',' <% name);
select * from simple_case where (',' <% name); -- returns normally
explain select * from simple_case where ('a' <% name) and (',' <% name);
select * from simple_case where ('a' <% name) and (',' <% name); -- returns
normally
explain select * from simple_case where ('a' <% name) and (',' <% name) and
('a' <% name);
select * from simple_case where ('a' <% name) and (',' <% name) and ('a' <%
name); -- returns normally
explain select * from simple_case where (',' <% name) and ('a' <% name);
select * from simple_case where (',' <% name) and ('a' <% name); -- infinite
loop
select * from simple_case where ('' <% name) and ('a' <% name); -- infinite
loop
```
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-bugs@postgresql.org
Cc: noreply@postgresql.org, pgsql-bugs@lists.postgresql.org, washwithcare@gmail.com
Subject: Re: BUG #19031: pg_trgm infinite loop on certain cases
In-Reply-To: <19031-0638148643d25548@postgresql.org>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox