BUG #18616: Long-running hash index build can not be interrupted

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From: PG Bug reporting form <noreply@postgresql.org>

To: pgsql-bugs@lists.postgresql.org

Cc: exclusion@gmail.com

Date: 2024-09-13T10:00:00Z

Lists: pgsql-bugs

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Allow _h_indexbuild() to be interrupted.
- fae55f0bb385 18.0 landed
- 418c6a2c72d2 17.0 landed
- e0857898b87b 15.9 landed
- d23109f4bd65 16.5 landed
- b49013f2e86a 14.14 landed
- b27215dbb42b 13.17 landed
- 813ade54806c 12.21 landed

The following bug has been logged on the website:

Bug reference:      18616
Logged by:          Alexander Lakhin
Email address:      exclusion@gmail.com
PostgreSQL version: 17rc1
Operating system:   Ubuntu 22.04
Description:        

The following script:
CREATE TABLE t(i int);
INSERT INTO t SELECT 1 FROM generate_series(1, 10000000);

SET maintenance_work_mem = '1GB';

SET statement_timeout = '90s';
CREATE INDEX hi ON t USING hash (i);

reaches a state, when the backend can not be interrupted.

gdb shows that the code execution loops inside:
#0  _h_indexbuild (...) at hashsort.c:151
#1  0x0000557f3671cbf3 in hashbuild (...)
    at hash.c:183
...
with tups_done increasing slowly (given the total number of tuples).

Reproduced on all supported versions.