Re: [HACKERS] generated columns - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: [HACKERS] generated columns
Date
Msg-id CANP8+jJwr02Yt_ZD6XtAg-y8eQ5vg4VSEpXTkNM8P4t0iqHtYg@mail.gmail.com
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In response to Re: [HACKERS] generated columns  (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>)
Responses Re: [HACKERS] generated columns
List pgsql-hackers
On Tue, 6 Nov 2018 at 04:31, Peter Eisentraut <peter.eisentraut@2ndquadrant.com> wrote:
On 31/10/2018 08:58, Erikjan Rijkers wrote:
> I have also noticed that logical replication isn't possible on tables
> with a generated column.  That's a shame but I suppsoe that is as
> expected.

This is an issue we need to discuss.  How should this work?

The simplest solution would be to exclude generated columns from the
replication stream altogether.

IMHO...

Virtual generated columns need not be WAL-logged, or sent.

Stored generated columns should be treated just like we'd treat a column value added by a trigger.

e.g. if we had a Timestamp column called LastUpdateTimestamp we would want to send that value
 
Similar considerations also apply to foreign tables.  What is the
meaning of a stored generated column on a foreign table?

--
Simon Riggs                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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