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(at)pgmasters(dot)net