Re: logical decoding / rewrite map vs. maxAllocatedDescs

On 08/10/2018 11:13 PM, Andres Freund wrote:
> On 2018-08-10 22:57:57 +0200, Tomas Vondra wrote:
>>
>>
>> On 08/09/2018 07:47 PM, Alvaro Herrera wrote:
>>> On 2018-Aug-09, Tomas Vondra wrote:
>>>
>>>> I suppose there are reasons why it's done this way, and admittedly the test
>>>> that happens to trigger this is a bit extreme (essentially running pgbench
>>>> concurrently with 'vacuum full pg_class' in a loop). I'm not sure it's
>>>> extreme enough to deem it not an issue, because people using many temporary
>>>> tables often deal with bloat by doing frequent vacuum full on catalogs.
>>>
>>> Actually, it seems to me that ApplyLogicalMappingFile is just leaking
>>> the file descriptor for no good reason. There's a different
>>> OpenTransientFile call in ReorderBufferRestoreChanges that is not
>>> intended to be closed immediately, but the other one seems a plain bug,
>>> easy enough to fix.
>>>
>>
>> Indeed. Adding a CloseTransientFile to ApplyLogicalMappingFile
>> solves the issue with hitting maxAllocatedDecs. Barring objections
>> I'll commit this shortly.
>
> Yea, that's clearly a bug. I've not seen a patch, so I can't quite
> formally sign off, but it seems fairly obvious.
>

I think the fix can be as simple as attached ... I'm mostly afk for the
weekend, so I'll commit & backpatch on Monday or so.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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