USER_JOINGROUPS describes join groups belonging to the user. A join group is a user-created object that consists of two or more columns that can be meaningfully joined. The maximum number of columns that can be included in a join group is 255. The USER_JOINGROUPS columns (except for JOINGROUP_OWNER) are the same as those in DBA_JOINGROUPS.

In certain queries, join groups enable the database to eliminate the performance overhead of decompressing and hashing column values. Join groups require an In-Memory column store (IM column store).


This view is available starting with Oracle Database 12c Release 2 (

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