Re: PsqlODBC slow on UNION queries

> Well, as I said, doing the same test from PSQL, the performance
> difference is much less. I was really asking about the difference
> between psql and PsqlODBC:
>
>                            psql(output to file)         psqlodbc
> UNION               total time: < 12 sec        first row received after
> 30 seconds
> UNION ALL      total time < 4 sec           first row received instantly

I suppose you have used Declare/Fetch turned on. Please try the same
query in psql client. The exact query you can find in mylog output.
It could be something like
DECLARE CURSOR <CURSOR_NAME> FOR SELECT <your select>;
FETCH FORWARD <number of rows to fetch at first time> FROM <CURSOR_NAME>;

If you have used Server side prepare then query is already different.
It use:
PREPARE <plan_name>[(paremters types)] AS <query>;
EXECUTE <plan_name> [(parameters)];

Regards,

Luf