Horton

Re: Dropped and generated columns might cause wrong data on subs when REPLICA IDENTITY FULL

Önder Kalacı <onderkalaci@gmail.com>

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From: Önder Kalacı <onderkalaci@gmail.com>
To: "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-03-21T12:02:58Z
Lists: pgsql-hackers

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Hi Shi Yu,

>
>
> 1.
>  $node_publisher->safe_psql(
>         'postgres', qq(
>                 ALTER TABLE dropped_cols DROP COLUMN b_drop;
> +               ALTER TABLE generated_cols DROP COLUMN b_gen;
>  ));
>  $node_subscriber->safe_psql(
>         'postgres', qq(
>                 ALTER TABLE dropped_cols DROP COLUMN b_drop;
> +               ALTER TABLE generated_cols DROP COLUMN b_gen;
>  ));
>
> I think we want to test generated columns, so we don't need to drop
> columns.
> Otherwise the generated column problem can't be detected.
>
>
Ow, what a mistake. Now changed (and ensured that without the patch
the test fails).



> 2.
> # The bug was that when the REPLICA IDENTITY FULL is used with dropped
> columns,
> # we fail to apply updates and deletes
>
> Maybe we should mention generated columns in comment of the test.
>
> makes sense


> 3.
> I ran pgindent and it modified some lines. Maybe we can improve the patch
> as the following.
>
> @@ -292,8 +292,8 @@ tuples_equal(TupleTableSlot *slot1, TupleTableSlot
> *slot2,
>                 att = TupleDescAttr(slot1->tts_tupleDescriptor, attrnum);
>
>                 /*
> -                * Ignore dropped and generated columns as the publisher
> -                * doesn't send those
> +                * Ignore dropped and generated columns as the publisher
> doesn't send
> +                * those
>                  */
>                 if (att->attisdropped || att->attgenerated)
>                         continue;
>
>  fixed


Attached patches again.


Thanks,
Onder KALACI

Commits

  1. Ignore generated columns during apply of update/delete.

  2. Ignore dropped columns during apply of update/delete.