Hi John,
How many rows are in the table? If the table is small with respect to
row count, and the pages are not very fragmented, ie, not many pages,
then PG is just doing the right thing here: seq scan is less expensive
than index scan in those cases. You can turn off enable_seqscan to just
make sure it does use the index.
Regards,
Michael Vitale
John Scalia wrote on 3/16/2020 12:26 PM:
> I’m a bit confused on an explain plan I just generated for a select statement. The plan’s first line begins with the
word“Append” followed by the usual (cost....) data. What in the world is an Append doing here? I’ve recently performed
anotheranalyze on the table, btw.
>
> Also, the query does not seem to be using an index, as the explain shows a pair of sequential scans, speaking of
which,the second sequential scan shows it’s on a table, called <table>_test. Which is a little strange, considering
thatdoes not exist.
>
> The query’s where clause is on a varchar(25) field. And that field has both a btree index and a trigram index on it.
I’vetried using where =, like, and ~ in order to see if I can get it to use an index. All attempts continue to say
sequentialscan.
> —
> Jay
> Sent from my iPad
>