
The Data Dictionary
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Table, column, and view views
Tables are the most important building blocks of an Oracle
database. These views provide information about tables, col-
umns, clusters, and views:
Dynamic Views
The dynamic performance data dictionary views (the V$
views) mainly provide information about the Oracle
instance, as well as information that the instance maintains
about the database. The views in this category are consid-
ered dynamic because their contents change based upon how
the instance is performing. The contents of these views are
representative of the total instance or cluster workload,
rather than the performance of one specific SQL statement.
*_ALL_TABLES
Lists all object and relational tables.
*_CLU_COLUMNS
Lists all cluster keys.
*_CLUSTER_HASH_EXPRESSIONS
Lists the hash values used for the optional
cluster hash indexes.
*_CLUSTERS
Lists all clusters in the database.
*_COL_COMMENTS
Shows comments on all table and view columns.
*_EXTERNAL_LOCATIONS
Lists the sources for the external tables.
*_EXTERNAL_TABLES
Describes the attributes of external tables.
*_TAB_COL_STATISTICS
Contains column information about analyzed
columns.
*_TAB_COLUMNS
Shows all table and view columns.
*_TAB_COMMENTS
Shows all comments on tables and views.
*_TAB_HISTOGRAMS
Shows all table histograms.
*_TABLES
Shows all relational tables.
*_UPDATABLE_COLUMNS
Lists columns that can be updated in views
with joins.