Re: pgsql: Make WAL segment size configurable at initdb time.

On 9/20/18 7:59 PM, Michael Paquier wrote:
> On Thu, Sep 20, 2018 at 11:48:08AM -0400, David Steele wrote:
>>        </term>
>>        <listitem>
>>         <para>
>> -        Reports the number of blocks (pages) in a WAL segment file.
>> -        The total size of a WAL segment file in bytes is equal to
>> -        <varname>wal_segment_size</varname> multiplied by <varname>wal_block_size</varname>;
>> -        by default this is 16MB.  See <xref linkend="wal-configuration"/> for
>> +        Reports the size of write ahead log segments.
>> +        The default value is 16MB. See <xref linkend="wal-configuration"/> for
>>          more information.
>>         </para>
>>        </listitem>
>
> The GUC wal_segment_size reports as well 16MB in v10 or older versions,
> so shouldn't the mention to wal_block_size be removed even further down?

Oddly, the GUC reports 16GB on `show wal_segment_size` but you get 2048
when querying pg_settings.  I thought that was just the normal behavior
for older versions -- and it might be a problem to change it.

--
-David
david@pgmasters.net