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Subject: Re: max_slot_wal_keep_size and wal_keep_segments
To: Fujii Masao <masao.fujii@oss.nttdata.com>,
 Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: alvherre@2ndquadrant.com, pgsql-hackers@postgresql.org
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From: David Steele <david@pgmasters.net>
Message-ID: <6479e9a4-0a9d-0772-0401-2c5d0de03ea7@pgmasters.net>
Date: Fri, 17 Jul 2020 07:24:07 -0400
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On 7/17/20 5:11 AM, Fujii Masao wrote:
> 
> 
> On 2020/07/14 20:30, David Steele wrote:
>> On 7/14/20 12:00 AM, Fujii Masao wrote:
>>>
>>> The patch was no longer applied cleanly because of recent commit.
>>> So I updated the patch. Attached.
>>>
>>> Barring any objection, I will commit this patch.
>>
>> This doesn't look right:
>>
>> +   the <xref linkend="guc-wal-keep-size"/> most recent megabytes
>> +   WAL files plus one WAL file are
>>
>> How about:
>>
>> +   <xref linkend="guc-wal-keep-size"/> megabytes of
>> +   WAL files plus one WAL file are
> 
> Thanks for the comment! Isn't it better to keep "most recent" part?
> If so, what about either of the followings?
> 
> 1. <xref linkend="guc-wal-keep-size"/> megabytes of WAL files plus
>      one WAL file that were most recently generated are kept all time.
> 
> 2. <xref linkend="guc-wal-keep-size"/> megabytes + <xref 
> linkend="guc-wal-segment-size"> bytes
>      of WAL files that were most recently generated are kept all time.

"most recent" seemed implied to me, but I see your point.

How about:

+   the most recent <xref linkend="guc-wal-keep-size"/> megabytes of
+   WAL files plus one additional WAL file are

Regards,
-- 
-David
david@pgmasters.net