DBA_HIST_ROWCACHE_SUMMARY displays historical summary statistics for data dictionary activity. This view contains snapshots of V$ROWCACHE.
| Column | Datatype | NULL | Description | 
|---|---|---|---|
| SNAP_ID | NUMBER | Unique snapshot ID | |
| DBID | NUMBER | Database ID for the snapshot | |
| INSTANCE_NUMBER | NUMBER | Instance number for the snapshot | |
| PARAMETER | VARCHAR2(32) | Name of the initialization parameter that determines the number of entries in the data dictionary cache | |
| TOTAL_USAGE | NUMBER | Sum of the total number of entries in the cache | |
| USAGE | NUMBER | Number of cache entries that contain valid data | |
| GETS | NUMBER | Total number of requests for information on the data object | |
| GETMISSES | NUMBER | Number of data requests resulting in cache misses | |
| SCANS | NUMBER | Number of scan requests | |
| SCANMISSES | NUMBER | Number of times a scan failed to find the data in the cache | |
| SCANCOMPLETES | NUMBER | For a list of subordinate entries, the number of times the list was scanned completely | |
| MODIFICATIONS | NUMBER | Number of inserts, updates, and deletions | |
| FLUSHES | NUMBER | Number of times flushed to disk | |
| DLM_REQUESTS | NUMBER | Number of DLM requests | |
| DLM_CONFLICTS | NUMBER | Number of DLM conflicts | |
| DLM_RELEASES | NUMBER | Number of DLM releases |