Re: Conflict detection for update_deleted in logical replication

On Tue, Sep 2, 2025 at 3:30 PM shveta malik <shveta.malik@gmail.com> wrote:
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> > > Here is V70 patch set.
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Please find a few comments on v70-003:

1)
Doc of dead_tuple_retention_active says:
True if retain_dead_tuples is enabled and the retention duration for
information used in conflict detection is within
max_retention_duration

Doc of subretentionactive says:
The retention status of information (e.g., dead tuples, commit
timestamps, and origins) useful for conflict detection. True if
retain_dead_tuples is enabled, and the retention duration has not
exceeded max_retention_duration, when defined.

There is hardly any difference between the two. Do we really need to
have 'dead_tuple_retention_active' when we already have
'subretentionactive'?

2)
Doc wise, there is no difference between the two, but there is a small
window when sub's subretentionactive will show true while stat's
dead_tuple_retention_active will show false. This will be when worker
is waiting for the launcher to assign its oldest-xid after it has
marked itself as 'resuming'.
If we decide to retain 'dead_tuple_retention_active', then do we need
to indicate the small difference between the 2 fields in the doc?

3)
We can add a test when we stop-retention to see if this is showing
false. Currently there are 2 places in the test where we check this
field to see if it is true. I think we can shift both in the same
test. One check before stop-retention, one check after stop-retention.

thanks
Shveta