SubQuery Performance - Mailing list pgsql-performance

Hi All,

I have a poor performance SQL as following. The table has about 200M
records, each employee have average 100 records. The query lasts about
3 hours. All I want is to update the flag for highest version of each
client's record. Any suggestion is welcome!

Thanks,

Mike


====SQL===========
update empTbl A
set flag=1
where
rec_ver =
( select max(rec_ver)
from empTbl
where empNo = A.empNo)



===Table empTbl=====

empTbl
{
int empNo;
int flag;
char[256] empDesc;
int rec_ver;
}