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How is data dictionary used in Oracle Database?
Because Oracle Database stores data dictionary data in tables, just like other data, users can query the data with SQL. For example, users can run SELECT statements to determine their privileges, which tables exist in their schema, which columns are in these tables, whether indexes are built on these columns, and so on.
Which is the view of all objects in Oracle?
ALL_OBJECTS describes all objects accessible to the current user. DBA_OBJECTS describes all objects in the database. USER_OBJECTS describes all objects owned by the current user. This view does not display the OWNER column. Note: OBJECT_ID and DATA_OBJECT_ID display data dictionary metadata.
How many views are in the data dictionary?
The data dictionary consists of numerous tables and views created by the database instance. User schemas generally have no privileges on these tables; Oracle Database grants only SELECT access on the views. Most data dictionary views come in three versions:
How to find all objects in a database?
DBA_OBJECTS describes all objects in the database. USER_OBJECTS describes all objects owned by the current user. This view does not display the OWNER column. Note: OBJECT_ID and DATA_OBJECT_ID display data dictionary metadata.
Is the Comments column cached in Oracle Database?
The COMMENTS columns describing the tables and their columns are not cached in the dictionary cache, but may be cached in the database buffer cache. Other Oracle Database products can reference existing views and create additional data dictionary tables or views of their own.
How many members does a data dictionary have?
Not all views sets have three members. For example, the data dictionary contains a DBA_LOCK view but no ALL_LOCK view. The system-supplied DICTIONARY view contains the names and abbreviated descriptions of all data dictionary views.
What do you mean by virtual column in Oracle?
Summary: in this tutorial, you will learn about Oracle virtual columns and how to use them in your database tables. A virtual column is a table column whose values are calculated automatically using other column values, or another deterministic expression.