Fujii Masao <masao.fujii@gmail.com> writes:
> Hi,
>
> When multiple relations are deleted at the same transaction,
> the files of those relations are deleted by one call to smgrdounlinkall(),
> which leads to scan whole shared_buffers only one time. OTOH,
> during recovery, smgrdounlink() (not smgrdounlinkall()) is called
> for each file to delete, which leads to scan shared_buffers multiple times.
> Obviously this can cause to increase the WAL replay time very much
> especially when shared_buffers is huge.
Forgot to mention version in my TLDR prev reply :-)
version
------------------------------------------------------------------------------------------------------------------------------------------------
PostgreSQL 9.5.12 on x86_64-pc-linux-gnu (Ubuntu 9.5.12-1.pgdg16.04+1), compiled by gcc (Ubuntu
5.4.0-6ubuntu1~16.04.9)5.4.0 20160609, 64-bit
(1 row)
>
> To alleviate this situation, I'd like to propose to change the recovery
> so that it also calls smgrdounlinkall() only one time to delete multiple
> relation files. Patch attached. Thought?
>
> Regards,
--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net
p: 312.241.7800
