| From: | Petr Jelinek <petr(at)2ndquadrant(dot)com> |
|---|---|
| To: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: Logical decoding slots can go backwards when used from SQL, docs are wrong |
| Date: | 2016-03-14 09:56:06 |
| Message-ID: | 56E68AB6.6000004@2ndquadrant.com |
| Views: | Whole Thread | Raw Message | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 14/03/16 10:48, Craig Ringer wrote:
>
> You btw can emulate asking for the specific LSN in SQL interface by
> first calling the pg_logical_slot_get_changes function with upto_lsn
> set to whatever lsn you expect to start at, but it's ugly.
>
>
> Ugh.
>
> I didn't realise pg_logical_slot_get_changes could backtrack by setting
> an upto_lsn in the past. That doesn't seem like something we should
> really be doing - if it's a limit, and we're already past that limit, we
> should just be returning the empty set.
>
Not past, future from the point of old confirmed_lsn at least. The point
was that the next call will start from whatever lsn you specified as
upto_lsn.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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