Oracle Core: Essential Internals for DBAs and Developers

The Dictionary Cache

The dictionary cache—also called the row cache because, effectively, it is used to cache individual rows of data from the data dictionary rather than data blocks—is the place where Oracle stores details of object definitions. We can view a summary of the content of this cache with a query against view v$rowcache. The results below come from an instance running 10g.

If you run the sample query against v$rowcache in 11g, you will see a couple of anomalies. One of the caches (cache# 11: dc_object_ids) has disappeared from v$rowcache, although it is still visible in v$rowcache_parent as cache# 11 but renamed to dc_objects; and cache# 7 has lost its parent entry, which seems to have migrated into cache# 10. Whether these are accidents ...