Hello,
I have ported a database from MS SQL Server to PostgreSQL. The database has
40 tables and 117 indexes which I defined for the same fields as in MS SQL.
I converted the data using some SQL output from MS SQL server and inserted
it with psql.
Now I started some performance comparisons and did the following statement:
SELECT Hauptdaten_Fall.MeldeKategorie, Count(Hauptdaten_Fall.ID) AS Anz
FROM Hauptdaten_Fall
WHERE (((Hauptdaten_Fall.IstAktuell)=20))
GROUP BY Hauptdaten_Fall.MeldeKategorie
ORDER BY Hauptdaten_Fall.MeldeKategorie;
(sorry for the German names used here).
The MS-SQL server represents the result "immediately" - you just not notice
any delay. If I do it on the PostgreSQL server it takes 30s on comparable
hardware :-(((.
I really have no idea what caused this big difference in speed which would
forbid the use of PostgreSQL for our application. How can I checked
whether the indexes I created are really used? What could be other
reasons for such a big difference in speed?
I´m using PostgreSQL 7.1.2 on Debian GNU/Linux (testing).
Any help appreciated
Andreas.