Tom Lane [tgl@xxxxxxxxxxxxx] wrote:
Some experimentation suggests that it might help to provide a 2-column
index on (ts_id, ts_interval_start_time). This is still going to be
scanned in order by ts_id, but it will be possible to check the
ts_interval_start_time condition in the index, eliminating a large
number of useless trips to the heap. Whether this type of query is
important enough to justify maintaining an extra index for is something
you'll have to decide for yourself...
Thanks to all for the analysis and suggestions. Since the number of rows
in an hour < ~500,000, brute force looks to be a fast solution:
select ts_id from ... where ts_interval_start_time >= ... and ...
This query runs very fast as does a single pass through the ids to find
the min and max.
Brian
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