Re: Query is taking too long i intermittent

Justin Pryzby <pryzby@telsasoft.com> writes:
> On Mon, Jun 06, 2022 at 03:28:43PM +0530, Mayank Kandari wrote:
>> SELECT event_id FROM event WHERE (event_sec > time.seconds) OR
>> ((event_sec=time.seconds) AND (event_usec>=time.useconds) ORDER BY
>> event_sec, event_usec LIMIT 1

> I think it'd be better if the column was a float storing the fractional number
> of seconds.  Currently, it may be hard for the planner to estimate rowcounts if
> the conditions are not independent.  I don't know if it's related to this
> problem, though.

Also, even if you can't change the data representation, there's a more
idiomatic way to do that in SQL: use a row comparison.

SELECT ...
WHERE row(event_sec, event_usec) >= row(time.seconds, time.useconds) ...

I doubt this is notably more execution-efficient, but if you're getting a
bad rowcount estimate it should help with that.  It's easier to read too.

            regards, tom lane