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scion The user can check the session, query, transaction, lock, service thread, and memory DB GC status in real time through meta table and performance view. The  The ERD below shows the join relationship between the meta table used in the monitoring query and the performance view in which only the main key columns to be referred join query are indicated is as follows.

v$memgc, which is marked separately, is a performance view for the memory DB GC, and has no direct relationship with other meta tables and performance views, but is used with a specific column of v$transaction.


Main Meta Tables


    This is the most basic because it can check It is a meta table that is widely used as a meta table to store database user information such as the USER_NAME as a meta table that stores database user information.

    This is a meta table that stores not only tables (including queue tables), but also sequence and view information, so it is possible to check information such as the object name (TABLE_NAME), which is basically used with SYS_USERS_.


  • v$session
    This is a performance view that shows session information of the currently connected user.

  • v$statement, v$sqltext, v$plantext
    This is a performance view that shows query information and query level statistics related to the session, and it is possible to measure the execution time and frequency of queries. This is a view maintained only for one query that was executed last(execution)  This view shows one direct-execute query and several preparsed query information per session and disappears at the end of each session and multiple prepared queries, and disappears when the related session is terminated. The text of the query can also be checked up to 16K through this viewquery length shown in this view is 16K.

    If the text of the query exceeds 16K, use v$ sqltext, a performance view that shows the entire query text, and use v$plantext to check the execution plan corresponding to the query.

    As mentioned before, statistical information related to query execution among columns of v$statement is provided only when the TIMED_STATISTICS property is activated (1), so the user must check whether the property is activated. The default value of TIMED_STATISTICS is disabled (0).