Re: Recovery performance of DROP DATABASE with many tablespaces

On Mon, Jun 4, 2018 at 9:46 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:

> Generally the recovery performance of DROP DATABASE is not critical
> for many users. But unfortunately my colleague's project might need to
> sometimes drop the database using multiple tablespaces, for some reasons.
> So, if the fix is not so complicated, I think that it's worth applying
> that.
>

Agree, in isolation need for this improvement is not felt, but yes any
improvements for single serialized replay process is definitely helpful.

> The straight approach to avoid such unnecessary scans is to change
> DROP DATABASE so that it generates only one XLOG_DBASE_DROP record,
> and register the information of all the tablespace into it. Then, WAL
> replay
> of XLOG_DBASE_DROP record scans shared_buffers once and deletes
> all tablespaces. POC patch is attached.
>

Also, irrespective of performance improvement looks better to just have
single xlog record for the same.