Re: BUG #14771: "Logical decoding" does not cover the impact of "TRUNCATE TABLE" command

2017-08-07 9:20 GMT-03:00 <hillel(dot)eilat(at)attunity(dot)com>:
> PostgreSQL version: 9.4.4
> Operating system: Windows 7
> Description:
>
I advise you to use a recent version (10?) because logical decoding
has been improved in the last years.

> I work on a mission of synchronizing data between PostgreSQL database and a
> "foreign" target database of choice.
>
This is not a bug.

> From "Logical Decoding" perspective - "TRUNCATE TABLE" is logically
> equivalent to "DELETE FROM TABLE".
> Both affect the contents of the PostgreSQL database identically.
> However - "DELETE FROM TABLE" will be reflected at the target database
> properly - as expected - while "TRUNCATE" will NOT!!.
>
TRUNCATE is a DDL command. DDL commands are not supported (yet) by
logical decoding.

> "TRUNCATE" stands for a case where change in data contents at PostgreSQL are
> not handled by "Logical Decoding", hence synchronization is not achieved.
> Did I miss something?
> Is it the only case?
> How can one cope with this deficiency?
>
You have at least 4 options:

(i) block TRUNCATE statement (via REVOKE);
(ii) write a plugin using ProcessUtility_hook to block TRUNCATE statement;
(iii) write a plugin using ProcessUtility_hook to convert it into
DELETE FROM table;
(iv) modify postgres to support TRUNCATE (logical) replication.

--
Euler Taveira Timbira -
http://www.timbira.com.br/
PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento