Re: Remote query very slow
От | Oliver Jowett |
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Тема | Re: Remote query very slow |
Дата | |
Msg-id | 415C80C2.4010404@opencloud.com обсуждение исходный текст |
Ответ на | Remote query very slow ("Johann Robette" <jrobette@onyme.com>) |
Ответы |
RE : Remote query very slow
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Список | pgsql-jdbc |
Johann Robette wrote: > I’ve installed postgres 7.3.5 on a fedora server. It works fine, at > least on a local basis. I perform an easy select * from a table and I > get the answer in approximatively 1s. > > Now, I used the jdbc driver (jdbc3) for postgres. It connects fine but, > performing the same query, I get the answer in 7s. > > What could be my problem? Is it really a "remote query" problem? Or is it just a difference between using psql and JDBC? How fast is the query if you run it "remotely" via psql? (psql -h server database) GC is the most likely culprit if you are running with default heap settings and a large data set. Without instructions to the contrary (e.g. Statement.setFetchSize) the driver will try to pull the entire resultset into heap before returning from query execution. Try turning on -verbose:gc on your JVM and see how much time is spent doing GC. You probably want to upgrade both your server and JDBC driver (assuming you're using the 7.3-era driver) if you can. The 7.3 server is getting quite old now, and there are a lot of bugfixes in the current driver that aren't in the 7.3 JDBC driver. -O
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