Re: About dropped notifications

tgl(at)sss(dot)pgh(dot)pa(dot)us (Tom Lane) writes:
> CSN <cool_screen_name90001(at)yahoo(dot)com> writes:
>> I'm considering setting up a script that listens for
>> notifications for a table and if a row is deleted the
>> script will delete that row's corresponding files. If
>> there are thousands of rows in the table, and I do
>> "delete from table", or even "delete from table where
>> id >1000 and id<2000", will the script be notified of
>> the deletion of each and every row (and subsequently
>> be able to delete that row's files), or will only one
>> notify event be received (or some number less than the
>> actual number of rows deleted)?
>
> Depends where you are doing the notify from ... but I think
> with the current implementation, a transaction will emit only
> one notify per notify event name, even if NOTIFY is executed
> many times within the transaction.

An interesting question is whether or not the relevant tuple in
pg_listener gets invalidated once, or whether doing 2500 attempted
NOTIFY requests blows through 2500 copies.
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