Re: Is a Multithreaded Ingres On the Horizon???

perl_at_dwrsun4.UUCP (Robert Perlberg) writes:

|There could be other advantages besides prioritizing. I have found
|that a single Ingres server can only seem to handle 2 queries at a
|time. We have had situations where 2 big queries (big being defined as
|queries which take many minutes to run) were running on the same server
|process at the same time. During this time, no other users could start
|any queries on this server and users just trying to connect could not
|connect. At the time we were running one DBMS server on a one-cpu
|machine. Having two big queries running effectively shut down the
|system for all the other users. Running multiple DBMS servers, even on
|a one-cpu machine, solved this problem. The machine may not run at
|100% efficiency under these conditions, but a slightly slower than
|normal system is much better than a completely dead one. So, I regard
|the number of DBMS servers to be more a function of how many concurrent
|users you need to support rather than how many cpu's you have.

You probably could have solved this problem by playing with the -quantum parameter in rundbms.opt. This allows you to change the time sharing between cpu intensive queries to prevent them monoplizing the server. See the dba guide for details.

On the note of different priority servers, we were advised by Ingres not to run any bits of the installation (ingres processes) at a different priority from the rest as it tends to cause problems with inter-process communication under heavy load.

--
Richard Begg (richard_at_asis.unimelb.edu.au)
Admin Systems and Info Services - University of Melbourne.