Re: Adding REPACK [concurrently] - Mailing list pgsql-hackers

From Antonin Houska
Subject Re: Adding REPACK [concurrently]
Date
Msg-id 121156.1775818667@localhost
Whole thread Raw
In response to Re: Adding REPACK [concurrently]  (Alexander Lakhin <exclusion@gmail.com>)
List pgsql-hackers
Alexander Lakhin <exclusion@gmail.com> wrote:

> Could you please look at an assertion failure produced by the following
> script, starting from 0d3dba38c:?
> createdb db1
> createdb db2
> 
> echo "
> CREATE TABLE t0 (a text);
> BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
> INSERT INTO t0 VALUES ('a');
> SELECT pg_sleep(1);
> " | psql db1 &
> 
> echo "
> CREATE TABLE t1 (id int PRIMARY KEY);
> CREATE TABLE t2 (id int PRIMARY KEY, a TEXT, FOREIGN KEY (id) REFERENCES t1);
> SET min_parallel_table_scan_size = 1;
> REPACK (CONCURRENTLY) t2;
> " | psql db2
> wait
> 
> It triggers for me:
> TRAP: failed Assert("TransactionIdPrecedesOrEquals(TransactionXmin, RecentXmin)"), File: "procarray.c", Line: 2071,
PID:3529520
 

Attached is a fix that works for me.

Nevertheless, REPACK (CONCURRENTLY) in your test goes ahead only due to commit
0d3dba38c7, which will probably be reverted [1]. Then REPACK will wait for the
transaction in the other database (db1) to complete before it can actually
start.

Thanks for the report!

[1] https://www.postgresql.org/message-id/cdgw4sbbfcgk6du3iv54r2dgiy4tfywoklbotlmj4irxavdcr3@glxfw5jj277q

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com


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