Re: Too rigorous assert in reorderbuffer.c

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Arseny Sher <a(dot)sher(at)postgrespro(dot)ru>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Lakhin <a(dot)lakhin(at)postgrespro(dot)ru>
Subject: Re: Too rigorous assert in reorderbuffer.c
Date: 2019-02-05 21:11:19
Message-ID: 20190205211118.GA30474@alvherre.pgsql
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On 2019-Jan-31, Arseny Sher wrote:

> My colleague Alexander Lakhin has noticed an assertion failure in
> reorderbuffer.c:1330. Here is a simple snippet reproducing it:
> SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
> create table t(k int);
> begin;
> savepoint a;
> alter table t alter column k type text;
> rollback to savepoint a;
> alter table t alter column k type bigint;
> commit;
> SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'include-xids', '0', 'skip-empty-xacts', '1');

Hmm, the new test introduced by your patch fails in early branches (at
least 9.4): the transaction is decoded like this:

! data
! -----------------------------------------------------
table public.tr_sub_ddl: INSERT: data[integer]:42
+ table public.pg_temp_16445: INSERT: data[bigint]:42
table public.tr_sub_ddl: INSERT: data[bigint]:43
! (5 rows)

note the additional pg_temp_XYZ row in the middle. This is caused by
the rewrite in ALTER TABLE. Peter E fixed that in Pg11 in commit
325f2ec55; I don't think there's much to do in the backbranches other
than hide the pesky record to avoid it breaking the test.

Álvaro Herrera
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2019-02-05 21:20:54 Re: Changing SQL Inlining Behaviour (or...?)
Previous Message AJG 2019-02-05 20:30:25 Re: Is zheap on track for PostgreSQL 12.0?