From: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Ants Aasma <ants(dot)aasma(at)eesti(dot)ee>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Andres Freund <andres(at)anarazel(dot)de>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Reviewing freeze map code |
Date: | 2016-05-11 02:40:23 |
Message-ID: | CAD21AoBU1LB76Hgc_KQ5T=SWGcu-dM8LovtF0MZk0u4Ua87Odw@mail.gmail.com |
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Lists: | pgsql-hackers |
On Tue, May 10, 2016 at 11:30 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Mon, May 9, 2016 at 7:40 PM, Ants Aasma <ants(dot)aasma(at)eesti(dot)ee> wrote:
>> On Mon, May 9, 2016 at 10:53 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Sun, May 8, 2016 at 10:42 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>>> Attached draft patch adds SCANALL option to VACUUM in order to scan
>>>> all pages forcibly while ignoring visibility map information.
>>>> The option name is SCANALL for now but we could change it after got consensus.
>>>
>>> If we're going to go that way, I'd say it should be scan_all rather
>>> than scanall. Makes it clearer, at least IMHO.
>>
>> Just to add some diversity to opinions, maybe there should be a
>> separate command for performing integrity checks. Currently the best
>> ways to actually verify database correctness do so as a side effect.
>> The question that I get pretty much every time after I explain why we
>> have data checksums, is "how do I check that they are correct" and we
>> don't have a nice answer for that now. We could also use some ways to
>> sniff out corrupted rows that don't involve crashing the server in a
>> loop. Vacuuming pages that supposedly don't need vacuuming just to
>> verify integrity seems very much in the same vein.
>>
>> I know right now isn't exactly the best time to hastily slap on such a
>> feature, but I just wanted the thought to be out there for
>> consideration.
>
> I think that it's quite reasonable to have ways of performing an
> integrity check that are separate from VACUUM, but this is about
> having a way to force VACUUM to scan all-frozen pages
Or second way I came up with is having tool to remove particular _vm
file safely, which is executed via SQL or client tool like
pg_resetxlog.
Attached updated VACUUM SCAN_ALL patch.
Please find it.
Regards,
--
Masahiko Sawada
Attachment | Content-Type | Size |
---|---|---|
vacuum_scanall_v2.patch | text/x-patch | 11.1 KB |
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