Обсуждение: Performance Problem

On Tue, 15 Apr 2003, Pedro C. Arias wrote:

> Hello, i use PostgresSQL 7.3.2 on Mandrake 9.0, I create a Database to
> test performance vs. SQL-Server, the idea is migrate SQL-Server to
> Postgres. This test is retrieve a table sorted by a field ie: "select
> * from test order by id_field asc", postgress retrieve it in 43
> seconds and SQL-Server in 8 seconds The table has 100.000 records, why
> the diference, how acelerete the performance of postgres, have any
> tutorial on the web to optimize querys ?

What is the definition of test and what indexes does it have and what does
explain show for the query above?  If you haven't at least vacuumed or
analyzed the table it's likely running on the default statistics which is
probably not good, also you may want/need to look at raising sort_mem if
the sort is going out to disk.

On Wednesday 16 April 2003 07:10, Pedro C. Arias wrote:
> Hello, i use PostgresSQL 7.3.2 on Mandrake 9.0, I create a Database to test
> performance vs. SQL-Server, the idea is migrate SQL-Server to Postgres.
> This test is retrieve a table sorted by a field ie: "select * from test
> order by id_field asc", postgress retrieve it in 43 seconds and SQL-Server
> in 8 seconds The table has 100.000 records, why the diference, how
> acelerete the performance of postgres, have any tutorial on the web to
> optimize querys ?

There are too many variables to tune for. To start with, tune postgresql.conf.
Look for number of shared buffers and sort mem. Also vacuum periodically.

 More specific information would help.

 Shridhar