| From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
|---|---|
| To: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Block level parallel vacuum WIP |
| Date: | 2016-08-23 12:41:21 |
| Message-ID: | CAB7nPqTZ9e+vLMQ0wiR4eiEGTAvmfSsNuyWV9o2252fMkvDLnA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Aug 23, 2016 at 8:02 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> As for PoC, I implemented parallel vacuum so that each worker
> processes both 1 and 2 phases for particular block range.
> Suppose we vacuum 1000 blocks table with 4 workers, each worker
> processes 250 consecutive blocks in phase 1 and then reclaims dead
> tuples from heap and indexes (phase 2).
So each worker is assigned a range of blocks, and processes them in
parallel? This does not sound performance-wise. I recall Robert and
Amit emails on the matter for sequential scan that this would suck
performance out particularly for rotating disks.
--
Michael
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