undocumented parameters

Hi all , Does anybody know the meaning about the parameters below and how does it affect performance ? DD_HASHSIZE DS_HASHSIZE DS_POOLSIZE PC_POOLSIZE PC_HASHSIZE Thanks Ricardo

Ricardo; These are paired hidden parameters that tune the sizes of the data dictionary cache (DD_HASHMAX, DD_HASHSIZE); the data distribution cache, (DS_HASHSIZE, DS_POOLSIZE); and the stored procedure cache (PC_HASHSIZE, PC_POOLSIZE). These parameters are documented in the Performance Guide. DD_HASHMAX, DS_HASHSIZE, and PC_HASHSIZE need to be prime numbers, and set the number of lists for the cache. The companion parameters set the number of items in each list. The data dictionary cache, for example, defaults to DD_HASHMAX of 31 and DD_HASHSIZE of 10. That means that 310 data dictionary items are cached. If you have more than 310 tables open and active at one time, then some of these are going to be flushed out and the data dictionary re-read from disk next time the table is accessed. Same concept for data distributions and stored procedures. Both these caches default to 31 lists, 127 items in each list. You can help performance by sizing each of these to cache the number of concurrent active and open objects your instance and application uses - not necessarily just to the total number of tables/distributions/procedures. To change them from the defaults, add them with the desired values to the onconfig file and bounce the engine. You can monitor these caches using onstat commands: Data Dictionary onstat -g dic Data Distribution onstat -g dsc Stored Procedure onstat -g prc HTH... Mike =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Mike Lowe Certified Consulting Education Specialist Data Management Solutions IBM Software Group Tel: 303-773-5216 Tie Line: 565-5216 e-Fax: 413-674-2415 mlowe0@us.ibm.com WWW: ibm.com/software/data Hi all , Does anybody know the meaning about the parameters below and how does it affect performance ? DD_HASHSIZE DS_HASHSIZE DS_POOLSIZE PC_POOLSIZE PC_HASHSIZE Thanks Ricardo