Parallel Query Option causes excessive paging on DEC Unix 3.0 (Alpha)

I recently upgraded from 7.1.4 to 7.2.2 on a DEC Unix 3.0 Alpha platform. The Alpha is a 4-CPU system with 640 megabytes of physical memory. The SGA is about 250 megabytes, mostly buffers. When the following problems occurred, nothing else was running on the system. A query such as:     

    select count(*) from table where date-attribute between startDate and endDate

caused excessive page-in activity. This did not happen on 7.1.4. The table is defined with parallel(degree 3). The paging does not occur if less than 3 PQO servers are initiated. It seems that each PQ server process is paging in stuff that should be shared. The resident working set of each PQ server is about 210 megabytes, but most of this is probably the SGA, which is a shared segment. It almost seems that each PQ server is dealing with a private SGA!

This is a serious problem, and not one that was caused by an exotic combination of factors. (How could this get past Oracle's QA? ) I'd appreciate any help.

Thanks,
Marty Himmelstein
marty.himmelstein_at_valley.net Received on Thu Dec 21 1995 - 00:00:00 CET