| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Vacuum: allow usage of more than 1GB of work mem |
| Date: | 2016-09-06 06:45:45 |
| Message-ID: | CANP8+j+HfQf8+P2PQiZPKAShgc5LLXLW9+8+ZNy+urrdfHf7EQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 5 September 2016 at 21:58, Claudio Freire <klaussfreire(at)gmail(dot)com> wrote:
>>>> How long does that part ever take? Is there any substantial gain from this?
> Btw, without a further patch to prefetch pages on the backward scan
> for truncate, however, my patience ran out before it finished
> truncating. I haven't submitted that patch because there was an
> identical patch in an older thread that was discussed and more or less
> rejected since it slightly penalized SSDs.
OK, thats enough context. Sorry for being forgetful on that point.
Please post that new patch also.
This whole idea of backwards scanning to confirm truncation seems
wrong. What we want is an O(1) solution. Thinking.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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