Re: Include sequence relation support in logical replication

On Wed, Mar 25, 2020 at 12:27:28PM -0700, Andres Freund wrote:
> On 2020-03-24 16:19:21 -0700, Cary Huang wrote:
>> For the replication to make sense, the patch actually disables the WAL
>> update at every 32 nextval() calls, so every call to nextval() will
>> emit a WAL update for proper replication. This is done by setting
>> SEQ_LOG_VALS to 0 in sequence.c
>
> Why is that needed? ISTM updating in increments of 32 is fine for
> replication purposes? It's good imo, because sending out more granular
> increments would increase the size of the WAL stream?

Once upon a time, I was looking at the effects of playing with the
limit of a WAL record generated every 32 increments for a sequence,
and the performance difference is huge and noticeable.
--
Michael