Re: proposal: CREATE DATABASE vs. (partial) CHECKPOINT

>
>
>>
> To solve #1, we could redesign CREATE DATABASE so that replaying the
> DBASE_CREATE record doesn't zap the old directory, and also doesn't copy
> any files. We could instead just assume that if the transaction commits,
> all the files have been copied and fsync'd already, like we assume that if
> a CREATE INDEX commits in wal_level=minimal, the underlying file was
> fsync'd before the commit.
>

Do you mean that during a recovery, we just let the database directory be
and assume that it is in good shape since the transaction committed
originally?

> I wonder if we should bite the bullet and start WAL-logging all the files
> that are copied from the template database to the new database. When the
> template database is small (template0 is 6.4MB currently), that wouldn't
> generate too much WAL. We could perhaps do that only if the template
> database is small, and do the checkpoints otherwise, although I wouldn't
> like to have subtly different behavior depending on database size like that.

For the sort of workload Tomas described above (creating a lot of databases
on the fly), we may end up with a lot of WAL eventually if we do this.

Regards,

Atri