[Pgpool-hackers] Partial replication

[Guillaume Lelarge]

Le 18/02/2011 02:21, Tatsuo Ishii a écrit :
> Hi hackes,
> 
> After my talk of pgpool-II V3 at FOSDEM 2011, I got a question about
> the idea "partial replication", which allows to replicate part of
> a database cluster in replication mode.
> 
> This has been on my personal TODO list for years, and I start to think
> about the implementation design again.
> 
> - We could have "database level partial replication" and "table level
>   partial replication".
> 
> - "Database level partial replication" is easy to do. Just having a
>   list of databases to replicate (or not to replicate) and
>   pool_where_to_send() will look it. However cross database tables
>   such as pg_database must be always replicated.
> 
> - "Table level partial replication" is not so easy. In addition to
>   having a list of tables to replicate (or not to replicate), we would
>   want to have such a list for schemas.
> 
> - If we have such a schema list, we need to know which schema the
>   table belogs to. This is not super easy if the table is not schema
>   qualified but doable.
> 
> - Functions would be troublesome because we cannot know which table it
>   is going to write.
> 
> Just my memorandum. Please feel free to add comments.

As you say, databases would be easy.

I don't see an easy way to configure table names. Using a text file
would be a burden if the user has a big number of tables. If you want to
have such a feature, we need to provide a way to easyly configure the
replication feature. We already have a system DB available. We could
probably use it to "register" the tables to replicate.


-- 
Guillaume
 http://www.postgresql.fr
 http://dalibo.com