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Performance Question - Simple Query with JDBC


Performance Question - Simple Query with JDBC



I'm starting a migration job from Oracle into EDB Advanced Server, after migrating table, data, view and constraint.

I use a little program in java with the driver JDBC Oracle and EDB, to test simple query like without display the result :

Select * from name_of_table;

But one table is problematic, it has 550 000 rows including columns with clob.

With JDBC Oracle no probleme, the query is execute in fews seconds, but with JDBC EDB it takes more time and crash with this message :

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space

I've try to up the heap size, but the problem still persists

I think the problem comes from the fact that Postgres is waiting the end of the query to display, so it is impossible for him to free.


If you have any solution ?


Thx and regards

EDB Team Member

Re: Performance Question - Simple Query with JDBC

Hi Hbach,


Considering the table size and the row count of 550 000  including columns with clob, we would suggest you to increase the java heap space to a value until that amount is sufficient.


Can you share more details on the available resources on the Source and Target Machine, theEDB  JDBC version and if feasible, the logs.


Re: Performance Question - Simple Query with JDBC

Hi Rahul,

Thx your answer

Effectively the db Oracle is install on Linux with 32 Go Ram whereas edb is install on different machine with 4 Go Ram.

I will install both on the same environnement (32Go) and retry the query.

This can also explain the time difference for some view.


I come back to you if have a news