Re: Too rigorous assert in reorderbuffer.c

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
! -----------------------------------------------------
BEGIN
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
COMMIT
! (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 https://www.2ndQuadrant.com/
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