Re: Performance suggestions? - Mailing list pgsql-general

From Paul Tillotson
Subject Re: Performance suggestions?
Date
Msg-id 41C0DCE1.7090103@shentel.net
Whole thread Raw
In response to Performance suggestions?  ("Harvey, Allan AC" <HarveyA@OneSteel.com>)
List pgsql-general
Allan,

Postgres is probably not the ideal solution to this problem.  If you'd
like to try this though, two points:

- If the table really only has 20 rows, drop the index.  If the table
really only has 20 active rows at a
time, then the planner will never use that index.
(run EXPLAIN on your query to see if it is using your index.  If not, it
is only slowing you down.)

- As said before, VACUUM frequently, maybe even every 10 seconds
(experiment with different intervals.)

Paul Tillotson

>I have a small table about 20 rows, a constant, that is receiving
>about 160 updates per second.
>The table is used to share gathered data to other process asynchronously.
>After 5 min it is 12 updates per second.
>Performance returns after a vacuum analyse.
>
>I'm using 7.4.5.
>This is the table structure
>               Table "public.lastscan"
>  Column   |            Type             | Modifiers
>-----------+-----------------------------+-----------
> pointnum  | integer                     | not null
> parameter | character varying(8)        | not null
> value     | double precision            | not null
> dt        | timestamp without time zone | not null
>Indexes:
>    "lsindex" btree (pointnum, parameter)
>
>
>


pgsql-general by date:

Previous
From: Alvaro Herrera
Date:
Subject: Re: Can a database notify all clients when something changes?
Next
From: Mike Rylander
Date:
Subject: Re: WAL/pg_xlog on Another Disk: Redundancy?