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Re: pg_get__*_ddl consolidation

David G. Johnston <david.g.johnston@gmail.com>

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From: "David G. Johnston" <david.g.johnston@gmail.com>
To: Japin Li <japinli@hotmail.com>
Cc: Andrew Dunstan <andrew@dunslane.net>, Zsolt Parragi <zsolt.parragi@percona.com>, Euler Taveira <euler@eulerto.com>, Álvaro Herrera <alvherre@kurilemu.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-04-02T13:35:59Z
Lists: pgsql-hackers 
On Thursday, April 2, 2026, Japin Li <japinli@hotmail.com> wrote:

>
> v3-0004
> ========
>
> 1.
> +       append_ddl_option(&buf, pretty, 4, "WITH TEMPLATE = template0");
>
> I'm curious why WITH TEMPLATE = template0 is hardcoded. For example:
>
>   [local]:1374846 postgres=# create database db01 IS_TEMPLATE true;
>   CREATE DATABASE
>   [local]:1374846 postgres=# create database db02 template db01;
>   CREATE DATABASE
>   [local]:1374846 postgres=# select pg_get_database_ddl('db02');
>                                                  pg_get_database_ddl
>   ------------------------------------------------------------
> -----------------------------------------------------
>    CREATE DATABASE db02 WITH TEMPLATE = template0 ENCODING = 'UTF8'
> LOCALE_PROVIDER = libc LOCALE = 'en_US.UTF-8';
>    ALTER DATABASE db02 OWNER TO japin;
>   (2 rows)
>
> Is this working as expected?
>
> It seems there's no way to reconstruct the WITH TEMPLATE clause, right?
> A comment here would help.


There is no way or use in constructing the original template clause, though
I agree it’s worth a comment.  At the end of the day the catalog data that
was found in the db01 database already exists in the db02 database when
executing these DLL reconstruction functions against the existing db02
database.  Taking nothing from the template is the correct behavior - hence
template0.

David J.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Use named boolean parameters for pg_get_*_ddl option arguments

  2. Convert ddlutils regression tests to TAP tests.

  3. Fix pfree crash in pg_get_role_ddl() and pg_get_database_ddl().

  4. Fixups for a4f774cf1c7

  5. Add infrastructure for pg_get_*_ddl functions

  6. Add pg_get_database_ddl() function

  7. Add pg_get_role_ddl() function

  8. Add pg_get_tablespace_ddl() function