DataDictionary.docVIP

Data Dictionary 1.Dictionary Cache Data Dictionary Cache Statistics ParameterGetsGetMisses% Cache Misses (1)CountUsagedc_histogram_defs11,6009,54382.0043dc_constraints15960.0065dc_used_extents2,9451,58354.003320dc_truncates27726.0021dc_constraint_defs4268620.001110dc_tablespace_quotas1442719.00227dc_sequence_grants811519.0021dc_constraint_defs5,59178014.00175174dc_segments14,2161,75012.0010299dc_histogram_data4,90258712.0020dc_indexes16,5201,76711.00133132dc_database_links51510.0052dc_objects26,9012,2238.00407403dc_object_ids4,6663668.00106105dc_table_grants6,7184537.00133132dc_sequences209147.001413dc_synonyms2,3681185.003433dc_columns352,31915,2294.001,4821,474dc_tables67,4211,5542.00251246dc_free_extents528,2333,1091.00173160dc_usernames12,251290.002019dc_tablespaces2,71540.0064dc_user_grants17,586200.005315dc_users22,440250.002016dc_rollback_segments56,56380.00189dc_tablespaces291,27070.00177 DATA DICTIONARY CACHE NOTES: ? Parameter - Name of the parameter that determines the number of entries in the data dictionary cache. ? Gets - Total number of requests for information on the data object. ? Getmisses - Number of data requests resulting in cache misses. ? % Cache Misses - Miss Ratio ? Count - Total number of entries in the cache ? Usage - Number of cache entries that contain valid data. ? This report shows the DC cache statistics (a part of the shared pool). ? Whenever the database parses a SQL statement, it scans the text for syntax and semantic correctness. The semantic check requires cross-referencing of the information in the SQL statement and the data dictionary, including the table names, columns-to-date relationships, column names, data types, and security access privileges. To resolve the relationships, Oracle uses the data dictionary cache in the SG