Re: Performance related to size of tables

If you want to speed up the elapsed times, then the first thing would be
to attempt to reduce the IO using some indexes, e.g. on test1(anumber),
test2(anumber), test3((anumber%13)), test3((anumber%5)) and
test4((anumber%27))

However if you wish to keep hammering the IO then the you would not use
any indexes. However elapsed times for operations like:

CREATE TABLE test4 AS SELECT ... FROM test1 JOIN test2 ON
test1.anumber=test2.anumber;

are going to increase non linearly with the size of the source table
test1 (unless there are indexes on the anumber columns).

I think this particular test is designed as a testbed for measuring IO
performance - as opposed to Postgresql performance.


regards

Mark

nbarraza@uolsinectis.com.ar wrote:

>Hi everyone,
>I found that performance get worse as the size of a given table
>increases. I mean, for example I´ve just run some scripts shown in
>
>http://www.potentialtech.com/wmoran/postgresql.php
>
>I understand that those scripts are designed to see the behavior of postgresql under different filesystems. However,
sincethem generate 
>a lot of I/O activity, I think they can be used to adjust some
>configuration parameters. In that way, I increased the number of tuples inserted in the initial table to 2000000 and
3000000.What  
>I saw is that the running time goes from 3 min., to 11 min. My question is, is it possible to use that test to tune
>some parameters?, if the answer is yes, what parameters should I change to get shorter running times?
>
>
>
>