| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com> |
| Cc: | Claudio Freire <klaussfreire(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Vacuum: allow usage of more than 1GB of work mem |
| Date: | 2016-09-16 13:59:32 |
| Message-ID: | CA+Tgmobjqu4ocSfkMTF+S4Xn4dx1tBxbNrXzPjhKiFPMN1t4ug@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Sep 16, 2016 at 9:47 AM, Pavan Deolasee
<pavan(dot)deolasee(at)gmail(dot)com> wrote:
> On Fri, Sep 16, 2016 at 7:03 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Thu, Sep 15, 2016 at 11:39 PM, Pavan Deolasee
>> <pavan(dot)deolasee(at)gmail(dot)com> wrote:
>> > But I actually wonder if we are over engineering things and
>> > overestimating
>> > cost of memmove etc. How about this simpler approach:
>>
>> Don't forget that you need to handle the case where
>> maintenance_work_mem is quite small.
>
> How small? The default IIRC these days is 64MB and minimum is 1MB. I think
> we can do some special casing for very small values and ensure that things
> at the very least work and hopefully don't regress for them.
Sounds like you need to handle values as small as 1MB, then.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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