Re: [BUGS] Breakage with VACUUM ANALYSE + partitions

On Mon, May 2, 2016 at 12:41 PM, Andres Freund <andres@anarazel.de> wrote:
> On 2016-05-02 12:29:45 -0400, Robert Haas wrote:
>> On Fri, Apr 29, 2016 at 7:58 PM, Andres Freund <andres@anarazel.de> wrote:
>> > Basically the reason for the problem is that mdsync() needs to access
>> > "formally non-existant segments" (as in ones where previous segments are
>> > < RELSEG_SIZE), because we queue (and the might be preexistant) fsync
>> > requests via register_dirty_segment() in mdtruncate().
>>
>> Shouldn't we just throw those flush requests away?
>
> Well, we explicity make them for truncations (register_dirty_segment()
> calls in mdtruncate()).  There's no comment as to why - I suspect the
> idea is that you want to make sure the truncation sticks in case of
> crash?

I dunno, I don't understand this well enough yet.

> FWIW, falling back to _mdfd_openseg() fixes the issue.

Can you post a patch?

-- 
Robert Haas
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