From: Tom Lane <tgl@sss.pgh.pa.us>
To: Josh Berkus <josh@agliodbs.com>
cc: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>,
	Jeff Davis <pgsql@j-davis.com>
Subject: Re: Index usage for tstzrange?
In-reply-to: <514A5088.6060101@agliodbs.com>
References: <514A5088.6060101@agliodbs.com>
Comments: In-reply-to Josh Berkus <josh@agliodbs.com>
	message dated "Wed, 20 Mar 2013 17:12:56 -0700"
Date: Wed, 20 Mar 2013 23:58:50 -0400
Message-ID: <1326.1363838330@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

Josh Berkus <josh@agliodbs.com> writes:
> I just noticed that if I use a tstzrange for convenience, a standard
> btree index on a timestamp won't get used for it.  Example:

> table a (
> 	id int,
> 	val text,
> 	ts timestamptz
> );
> index a_ts on a(ts);

> SELECT * FROM a WHERE ts <@ tstzrange('2013-01-01','2013-01-01 00:10:00')

> ... will NOT use the index a_ts.

Well, no.  <@ is not a btree-indexable operator.

What I find more disturbing is that this is what I get from the example
in HEAD:

regression=# explain SELECT * FROM a WHERE ts <@ tstzrange('2013-01-01','2013-01-01 00:10:00');
ERROR:  XX000: type 1184 is not a range type
LOCATION:  range_get_typcache, rangetypes.c:1451

Haven't traced through it to determine exactly what's happening, but
isn't this a legitimate usage?  And if it isn't, surely a more
user-facing error ought to be getting thrown somewhere upstream of here.

			regards, tom lane


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