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From: Atapys Sharsh <[email protected]>
To: [email protected]
Subject: Changing column filter for existing publication with WAL backlog
Date: Fri, 7 Mar 2025 15:25:54 +0000
Message-ID: <CANrdvu3jMWU6wE7vghiuOUoA5OMo7no3uuYjsnG8RN_03H_cJA@mail.gmail.com> (raw)

Hi,

Recently, I decided to add column filtering for our publication. The
commands I used were:
ALTER SUBSCRIPTION mysub DISABLE;

ALTER PUBLICATION mypub SET TABLE public.my_table(id, first_column,
another_column), TABLE public.other_table; -- excluding third_column

ALTER SUBSCRIPTION mysub ENABLE;

When I tested this approach in our staging environment, it worked as
expected – I stopped seeing updates to third_column. However, in production
I still see updates to that column. I also ran ALTER SUBSCRIPTION mysub
REFRESH PUBLICATION after noticing that updates were still being replicated.

Could this behavior be due to the large WAL backlog in production? At the
time I applied the column filter, the replication lag was around 4 TB (with
total storage being 16 TB). Should I expect that once production catches up
to WAL records generated after the change, updates to third_column will
eventually stop replicating?

Thanks in advance for your help.

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