| From: | Michael Paquier <michael(at)paquier(dot)xyz> |
|---|---|
| To: | Fujii Masao <fujii(at)postgresql(dot)org> |
| Cc: | pgsql-committers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: pgsql: Make DROP DATABASE command generate less WAL records. |
| Date: | 2019-11-21 12:17:40 |
| Message-ID: | 20191121121740.GA1651@paquier.xyz |
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| Thread: | |
| Lists: | pgsql-committers |
On Thu, Nov 21, 2019 at 12:11:58PM +0000, Fujii Masao wrote:
> Make DROP DATABASE command generate less WAL records.
>
> Previously DROP DATABASE generated as many XLOG_DBASE_DROP WAL records
> as the number of tablespaces that the database to drop uses. This caused
> the scans of shared_buffers as many times as the number of the tablespaces
> during recovery because WAL replay of one XLOG_DBASE_DROP record needs
> that full scan. This could make the recovery time longer especially
> when shared_buffers is large.
>
> This commit changes DROP DATABASE so that it generates only one
> XLOG_DBASE_DROP record, and registers the information of all the tablespaces
> into it. Then, WAL replay of XLOG_DBASE_DROP record needs full scan of
> shared_buffers only once, and which may improve the recovery performance.
Fujii-san, you have forgotten to bump XLOG_PAGE_MAGIC in
xlog_internal.h?
--
Michael
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