Re: logical replication busy-waiting on a lock

On Thu, Jun 1, 2017 at 2:28 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2017-06-01 14:17:44 +0200, Petr Jelinek wrote:
>> Thinking more about this, I am not convinced it's a good idea to change
>> exports this late in the cycle. I still think it's best to do the xid
>> assignment only when the snapshot is actually exported but don't assign
>> xid when the export is only used by the local session (the new option in
>> PG10). That's one line change which impacts only logical
>> replication/decoding as opposed to everything else which uses exported
>> snapshots.
>
> I'm not quite convinced by this argument. Exported snapshot contents
> are ephemeral, we can change the format at any time. The wait is fairly
> annoying for every user of logical decoding. For me the combination of
> those two fact implies that we should rather fix this properly.

+1. The change Andres is proposing doesn't sound like it will be
terribly high-impact, and I think we'll be happier in the long run if
we install real fixes instead of kludging it.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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