Martin, First off the data dictionary is listed under those views that start with DBA or USER. They point you at what your or others tables/objects are and their properties. As far as any view that starts with V$ those are dynamic performance views of internal data structures. They are not there to tell you what is in the caches, but how they are behaving. Dick Goulet Senior Oracle DBA/NA Team Lead PAREXEL International ________________________________ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Martin Berger Sent: Monday, September 21, 2009 4:16 PM To: ORACLE-L Subject: what is the data dictionary? Hi List, once again I stumble about two realy dumb (and related) questions: 1) what is the data dictionary (or how can I identify objects which belongs to it)? 2) is there any spyhole to view into the row cache (like v$bh for the buffer cache)? According to the documentation, the data dictionary is http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/glossary. htm#CNCPT2033 "A read-only collection of database tables and views containing reference information about the database, its structures, and its users." The row cache is defined with http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/glossary. htm#CNCPT44459 "A memory area in the shared pool <http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/glossary .htm#CBAIACIC> that holds data dictionary <http://download.oracle.com/docs/cd/E11882_01/server.112/e10713/glossary .htm#CHDJCHJA> information. The data dictionary cache is also known as the row cache because it holds data as rows instead of buffers, which hold entire data blocks." Even v$rowcache seems not as featured as I'd like it to be. This question is not based on any need, just pure curiosity. thank you for any hint, Martin -- //www.freelists.org/webpage/oracle-l