Re: Proposal: Generic WAL logical messages - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Proposal: Generic WAL logical messages
Date
Msg-id 20160406142912.ny3lo3y425xzs2mq@alap3.anarazel.de
Whole thread Raw
In response to Re: Proposal: Generic WAL logical messages  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Proposal: Generic WAL logical messages  (Simon Riggs <simon@2ndQuadrant.com>)
List pgsql-hackers
On 2016-04-06 10:24:52 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2016-04-06 10:15:59 -0400, Tom Lane wrote:
> >> Well, that's something worth thinking about.  I assume that
> >> pg_logical_slot_get_changes could be executed in a database different from
> >> the one where a change was originated?
> 
> > You can execute it, but you'll get an error:
> 
> Oh good.  I was afraid we had an unrecognized can o' worms here.

As posted nearby, there's a hole in that defense; for the messages
only. Pretty easy to solve though.

Allowing logical decoding from a difference would have a lot of
problems; primarily we couldn't actually look up any catalog state. But
even leaving that aside, it'd end up being pretty hard to interpret
database contents without knowledge about encoding.

Andres



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