From: | Melvin Davidson <melvin6925(at)gmail(dot)com> |
---|---|
To: | Adam Brusselback <adambrusselback(at)gmail(dot)com> |
Cc: | Tom Smith <tomsmith1989sk(at)gmail(dot)com>, PostgreSQL General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: first_value/last_value |
Date: | 2016-05-19 02:42:50 |
Message-ID: | CANu8FixVmZpbhRoH9VmX=9P1jw66wF_9_dmbRDFZE1x+o7nnxg@mail.gmail.com |
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On Wed, May 18, 2016 at 10:36 PM, Adam Brusselback <
adambrusselback(at)gmail(dot)com> wrote:
> Here is an example that works in a single query. Since you have two
> different orders you want the data back in, you need to use subqueries to
> get the proper data back, but it works, and is very fast.
>
> CREATE TEMPORARY TABLE foo AS
> SELECT generate_series as bar
> FROM generate_series(1, 1000000);
>
> CREATE INDEX idx_foo_bar ON foo (bar);
>
>
> SELECT *
> FROM (
> SELECT bar
> FROM foo
> ORDER BY bar asc
> LIMIT 1
> ) x
> UNION ALL
> SELECT *
> FROM (
> SELECT bar
> FROM foo
> ORDER BY bar desc
> LIMIT 1
> ) y;
>
> DROP TABLE foo;
>
Seems to me SELECT min(<column>), max(<column>) FROM deja.vu ; would also
work.
--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.
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