| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com>,Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Turning off HOT/Cleanup sometimes |
| Date: | 2014-09-19 20:30:34 |
| Message-ID: | 8e5dfcd2-800c-4998-8732-7fcb7aebc928@email.android.com |
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| Lists: | pgsql-hackers |
On September 19, 2014 10:16:35 PM CEST, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>On 19 September 2014 13:04, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
>> What I'm thinking about is that the smarts to enable pruning is all
>in
>> the executor nodes. So anything that updates the catalog without
>> going through the executor will never be subject to pruning. That
>> includes nearly all catalog-modifying code throughout the backend.
>
>Are you saying this is a problem or a benefit? (and please explain
>why).
I have no idea what Robert is thinking of, but I'd imagine its horrible for workloads with catalog bloat. Like ones involving temp tables.
I generally have serious doubts about disabling it generally for read workloads. I imagine it e.g. will significantly penalize workloads where its likely that a cleanup lock can't be acquired every time...
Andres
---
Please excuse brevity and formatting - I am writing this on my mobile phone.
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