Hello,
I'm having a surprising performance problem with the following simple
'highscore report'
select studentid, (select max(score) from
studentprofile prof where prof.studentid = students.studentid) from students;
I have indexes on students(studentid) and studentprofile(studentid).
Row counts: about 160 000 in each students and studentprofile.
Postgres version:
postgresql-8.1.8-1.fc5
postgresql-server-8.1.8-1.fc5
This is a dual-processor 3Ghz 64bit box with 2 GB mem.
Running the query takes 99% CPU and 1% mem.
I have the same data in MSSQL and there the query takes less than a
minute. With postgres it seems to take several hours.
Is there a way of making this faster?
Marko
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
