copy databases from two differend backups to one cluster

On 11/18/22 06:33, Joseph Kennedy wrote:

I would like to copy databases from two different pg_basebackup backups to
one lab environment database cluster on another server. Is it possible ?

It's a good idea to do it in that way.

Databases has your oid in pg_basebackup we can find it id in base
directory for example:

 base/

1

125859

14042

14043

2315410

2321461

2321462

2321463

Database OID (and directory name) we can find by :

SELECT oid from pg_database where datname = 'database name';

 Steps:

create empty databases on destination server (database oid they will be
probably different then on source databases)

stop Postgresql

cleanup destination directories eg. 2315410, 2321461, 2321462, 2321463

copy eg. content from pg_bassebackup01 base/(some OID) to 2315410 and 2321461

copy eg. content from pg_bassebackup02 base/(some OID) to 2321462 and 2321463

start postgresql

Is it a good or  very bad idea ?

Why can't you do pg_dump/pg_restore?

--
Angular momentum makes the world go 'round.

On 11/18/22 04:33, Joseph Kennedy wrote:

I would like to copy databases from two different pg_basebackup backups
to one lab environment database cluster on another server. Is it possible ?

It's a good idea to do it in that way.

Databases has your oid in pg_basebackup we can find it id in base
directory for example:

Is it a good or  very bad idea ?

Bad idea.

For why see:

https://www.postgresql.org/docs/current/storage-file-layout.html

and

https://www.postgresql.org/docs/current/storage-page-layout.html

There is more to a cluster then what is found in a given databases
directory. You can't, at the file(binary) level, just rip a database out
of one cluster and graft it into another.

If you want to do this then the options are:

1) As Ron suggested dump/restore.

2) Setting up logical replication.

--
Adrian Klaver
adrian.klaver@aklaver.com