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ManualiOracle.it |
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The data dictionary views consist of static and dynamic views: - The name "static" denotes that the information in this group of views only changes when a change is made to the data dictionary (a column is added to a table, a new database user is created, etc.). They are not relevant to this page. - The dynamic views are constantly updated while a database is in use; their contents relate primarily to performance. The dynamic views are also called fixed views. SYS owns the dynamic performance tables. By default, they are available only to the user SYS and to users granted SELECT ANY TABLE system privilege, such as SYSTEM. Their names all begin with V_$. Views are created on these tables, and then public synonyms are created for the views. The synonym names begin with V$. For almost every V$ view, Oracle has a corresponding GV$ (global V$) view. In Oracle RAC, querying a GV$ view retrieves the V$ view information from all qualified instances. In addition to the V$ information, each GV$ view contains an extra column named INST_ID of datatype NUMBER. The INST_ID column displays the instance number from which the associated V$ view information was obtained. Each Dynamic System Views belongs to one of the following categories: - Current State Views - Counter/Accumulator Views - Information Views Current State Views:
These views give a picture of what is currently happening on the system. Below is a listing these views that are commonly used: V$LOCK Locks currently held/requested on the instance V$LATCHHOLDER Sessions/processes holding a latch V$OPEN_CURSOR Cursors opened by sessions on the instance V$SESSION Sessions currently connected to the instance V$SESSION_WAIT Different resources sessions are currently waiting for Counter/Accumulator Views:
These views keep track of how many times some activity has occurred since instance/session startup. Select from the view directly to see activity since startup. Below is a listing these views that are commonly used: V$DB_OBJECT_CACHE Object level statistics in shared pool V$FILESTAT File level summary of the I/O activity V$LATCH Latch activity summary V$LATCH_CHILDREN Latch activity for child latches V$LIBRARYCACHE Namespace level summary for shared pool V$LIBRARY_CACHE_MEMORY Summary of the current memory use of the library cache V$MYSTAT Resource usage summary for your own session V$ROLLSTAT Rollback segment activity summary V$ROWCACHE Data dictionary activity summary V$SEGMENT_STATISTICS View for real-time monitoring of segment-level statistics V$SEGSTAT View for real-time monitoring of segment-level statistics V$SESSION_EVENT Session-level summary of all the waits for current sessions V$SESSTAT Session-level summary of resource usage since session startup V$LIBRARY_CACHE_MEMORY Simulation of the shared pool's LRU list mechanism V$SQL Child cursor details for V$SQLAREA V$SQLAREA Shared pool details for statements/anonymous blocks V$SYSSTAT Summary of resource usage V$SYSTEM_EVENT Instance wide summary of resources waited for V$UNDOSTAT Histogram of undo usage. Each row represents a 10-minute interval V$WAITSTAT Break down of buffer waits by block class Information Views:
In these views, the information is not as dynamic as in the current state view. Then, it does not need to be queried as often as the current state views Below is a listing these views that are commonly used: V$MTTR_TARGET_ADVICE Advisory information collected by MTTR advisory V$PARAMETER Information about the initialization parameters that are currently in effect for the session V$SYSTEM_PARAMETER Information about the initialization parameters that are currently in effect for the instance V$PROCESS Server processes (background and foreground) V$SEGSTAT_NAME Statistics property view for segment-level statistics V$SQL_PLAN Execution plan for cursors that were recently executed V$SQL_PLAN_STATISTICS Execution statistics of each operation in the execution plan V$SQLTEXT SQL text of statements in the shared pool V$STATISTICS_LEVEL Status of the statistics or advisories controlled by the STATISTICS_LEVEL initialization parameter
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