Data-dictionary configuration

The database server uses a hashing algorithm to store and locate information within the data-dictionary cache. The DD_HASHSIZE and DD_HASHMAX configuration parameters control the size of the data-dictionary cache.

To modify the number of buckets in the data-dictionary cache, use DD_HASHSIZE (must be a prime number). To modify the number of tables that can be stored in one bucket, use DD_HASHMAX.

For medium to large systems, you can start with the following values for these configuration parameters:

With these values, you can potentially store information about 2012 tables in the data-dictionary cache, and each hash bucket can have a maximum of 4 tables.

If the bucket reaches the maximum size, the database server uses a least recently used mechanism to clear entries from the data dictionary.


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