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

On 9/21/18 12:44 PM, David Steele wrote:
> On 9/21/18 12:53 AM, Michael Paquier wrote:
>> On Thu, Sep 20, 2018 at 06:23:54PM -0700, Andres Freund wrote:
>>> 16*M*B, right? If so, that's normal - pg_settings just reports the
>>> values in the underlying unit - which is XLOG_BLCKSZ, compile-time
>>> defaulting to 8KB. 8192 * 2048 = 16MB. That's the same in various other
>>> settings.
>>
>> Would it bring less confusion if we append something like "When querying
>> pg_settings"? I can see David's point the current phrasing is
>> confusing: we don't know if this comes from pg_settings or from SHOW.
>> It obviously refers to the former, but one can understand that it refers
>> to the latter.
>>
>> A second parameter in config.sgml where this formulation is used is
>> segment_size.
>
> That's why I used a default of 16MB instead of the byte value, because
> segment_size used 1GB instead of the byte value.

Not sure where we are on this, but for the record I still think the
description in PG11 needs to be corrected as in the patch. It doesn't
need to be back-patched and the default seems correct to me.

Thanks,
--
-David
david(at)pgmasters(dot)net