Re: draft RFC: concept for partial, wal-based replication

On Nov 30, 2009, at 1:55 AM, Craig Ringer
<craig(at)postnewspapers(dot)com(dot)au> wrote:

> Boszormenyi Zoltan wrote:
>
>> c. splitting wal into different replication sets
>
> Just a side note: in addition to its use for partial replication, this
> might have potential for performance-prioritizing databases or
> tablespaces.
>
> Being able to separate WAL logging so that different DBs, tablespaces,
> etc went to different sets of WAL logs would allow a DBA to give some
> databases or tablespaces dedicated WAL logging space on faster
> storage.
> If partial recovery is implemented, it might also permit less
> important
> databases to be logged to fast-but-unsafe storage such as a non-BBU
> disk
> controller with write cache enabled, without putting more important
> databases in the same cluster in danger.

The danger here is that if we make crash recovery more complex, we'll
introduce subtle bugs that will only be discovered after someone's
data is toast.

...Robert