Re: stale WAL files? - Mailing list pgsql-general

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Subject Re: stale WAL files?
Date
Msg-id 24253F34-C773-4DA7-8189-321CA54AB535@gmail.com
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In response to Re: stale WAL files?  (Michael Paquier <michael@paquier.xyz>)
List pgsql-general

> On Mar 29, 2019, at 6:58 AM, Michael Paquier <michael@paquier.xyz> wrote:
>
>> On Thu, Mar 28, 2019 at 09:53:16AM -0600, Rob Sargent wrote:
>> This is pg10 so it's pg_wal.  ls -ltr
>>
>>
>> -rw-------. 1 postgres postgres 16777216 Mar 16 16:33
>> 0000000100000CEA000000B1
>> -rw-------. 1 postgres postgres 16777216 Mar 16 16:33
>> 0000000100000CEA000000B2
>>
>>  ... 217 more on through to ...
>>
>> -rw-------. 1 postgres postgres 16777216 Mar 16 17:01
>> 0000000100000CEA000000E8
>> -rw-------. 1 postgres postgres 16777216 Mar 16 17:01
>> 0000000100000CEA000000E9
>> -rw-------. 1 postgres postgres 16777216 Mar 28 09:46
>> 0000000100000CEA0000000E
>
> In Postgres 10 and older versions, the server keeps WAL segment for
> the last completed segment, and the previous completed segment.  So
> even if a checkpoint is issued, the current WAL insert point is never
> really going to be on the first segment in pg_wal.  Isn't that the
> origin of what you think is a problem?  So, say, if you issue a
> checkpoint again, don't you see 0000000100000CEA000000B1 going away?
I had CEA000000015, generated today, as only entry since Mar 16. Issued checkpoint, soon had CEA0000016 and 15.  Five
minuteslater I still hav 15 and 16 (and of course all 271 from Mar 16). 

>
> In Postgres 11, WAL segments worth only one checkpoint are kept
> around.
> --
> Michael



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