Re: row filtering for logical replication

PSA my new incremental patch (v28-0002) that introduces row filter
validation for the publish mode "delete". The validation requires that
any columns referred to in the filter expression must also be part of
REPLICA IDENTITY or PK.

[This v28-0001 is identical to the most recently posted rebased base
patch. It is included again here only so the cfbot will be happy]

~~

A requirement for some filter validation like this has been mentioned
several times in this thread [1][2][3][4][5].

I also added some test code for various kinds of replica identity.

A couple of existing tests had to be modified so they could continue
to work (e.g. changed publish = "insert" or REPLICA IDENTITY FULL)

Feedback is welcome.

~~

NOTE: This validation currently only checks when the filters are first
created. Probably there are many other scenarios that need to be
properly handled. What to do if something which impacts the existing
filter is changed?

e.g.
- what if the user changes the publish parameter using ALTER
PUBLICATION set (publish="delete") etc?
- what if the user changes the replication identity?
- what if the user changes the filter using ALTER PUBLICATION in a way
that is no longer compatible with the necessary cols?
- what if the user changes the table (e.g. removes a column referred
to by a filter)?
- what if the user changes a referred column name?
- more...

(None of those are addressed yet - thoughts?)

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[1] https://www.postgresql.org/message-id/92e5587d-28b8-5849-2374-5ca3863256f1%402ndquadrant.com
[2] https://www.postgresql.org/message-id/CAA4eK1JL2q%2BHENgiCf1HLRU7nD9jCcttB9sEqV1tech4mMv_0A%40mail.gmail.com
[3] https://www.postgresql.org/message-id/202107132106.wvjgvjgcyezo%40alvherre.pgsql
[4] https://www.postgresql.org/message-id/202107141452.edncq4ot5zkg%40alvherre.pgsql
[5] https://www.postgresql.org/message-id/CAA4eK1Kyax-qnVPcXzODu3JmA4vtgAjUSYPUK1Pm3vBL5gC81g%40mail.gmail.com

Kind Regards,
Peter Smith.
Fujitsu Australia