Tuning the Data Dictionary

The above control the size of the in-memory Data Dictionary cache, the current settings and contents are reported by onstat -g dic. DD_HASHSIZE is the number of hash buckets in the cache and MUST be a prime number, it is reported as 'Number of lists'. IB the default is 127. DD_HASHMAX is the number of slots in each hash bucket and should be a small integer (default 31), it is reported as 'Maximum list size'. If you have close to or more than DD_HASHMAX * DD_HASHSIZE active tables in your instance, or access large numbers of remote tables that will swell the local cache, you should increase these values, at least DD_HASHSIZE. If you access many tables with similar names you should increase DD_HASHMAX to widen the buckets.

The above control the size of the in-memory Data Distribution cache, the current settings are reported by onstat -g dsc. The rules are similar as for the DD_ parameters. DS_HASHSIZE MUST be a prime number (default 31) and is called 'Number of lists' in onstat, this is the number of hash buckets in the distribution cache. DS_POOLSIZE is the number of number of entries total in the distribution cache integer (default 127) and is reported by name in the onstat output.

The above control the size of the in-memory Stored Procedure cache, the current settings are reported by onstat -g prc. The rules are similar as for the DD_ parameters. PC_HASHSIZE MUST be a prime number (default 31) and is called 'Number of lists' in onstat, this is the number of hash buckets in the procedure cache. PC_POOLSIZE is the number of number of entries total in the procedure cache integer (default 127) and is reported by name in the onstat output.