On 7/14/21 4:48 PM, Dilip Kumar wrote:
On Wed, Jul 14, 2021 at 8:04 PM Tomas Vondra
<tomas.von...@enterprisedb.com> wrote:
Perhaps the best way forward is to stick to the approach that INSERT
uses new, DELETE uses old and UPDATE works as DELETE+INSERT (probably),
and leave anything fancier (like being able to reference both versions
of the row) for a future patch.
If UPDATE works as DELETE+ INSERT, does that mean both the OLD row and
the NEW row should satisfy the filter, then only it will be sent?
That means if we insert a row that is not satisfying the condition
(which is not sent to the subscriber) and later if we update that row
and change the values such that the modified value matches the filter
then we will not send it because only the NEW row is satisfying the
condition but OLD row doesn't. I am just trying to understand your
idea. Or you are saying that in this case, we will not send anything
for the OLD row as it was not satisfying the condition but the
modified row will be sent as an INSERT operation because this is
satisfying the condition?
Good questions. I'm not sure, I probably have not thought it through.
So yeah, I think we should probably stick to the principle that what we
send needs to match the filter condition, which applied to this case
would mean we should be looking at the new row version.
The more elaborate scenarios can be added later by a patch allowing to
explicitly reference the old/new row versions.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
