Question

My web application needs to get the results of all the items which have their time value for this minute. My table has a time attributes

id, message, time, ...,

where time is of type timestamp with timezone.
I need to get a list of all entries where the time is the current minute. Comparing the entire value does not match because the timestamp has microsecond resolution.

Currently I am using the following query to return this list and it works, but I think there should be a more efficient way of doing this.

SELECT * FROM notification WHERE 
 date_part('year', time) = date_part('year', current_date) AND 
 date_part('month', time) = date_part('month', current_date) AND 
 date_part('day', time) = date_part('day', current_date) AND 
 date_part('hour', time) = date_part('hour', current_time) AND 
 date_part('minute', time) = date_part('minute', current_time);

I’d also like to know how to get the results for the this and the previous minute or the last ‘n’ minutes.
Database is PostgreSQL 8.4.3

Thanks

Answer 1

I’d try something like this:

WHERE
    time >= date_trunc('minute', now()) AND
    time < date_trunc('minute', now()) + INTERVAL '1 minute';

This will define the boundaries and search for times within that range, which means it still can use the index you have (or should have) on the time column.