The BYPASS_UJVC hint
Most views that contain multiple tables joined together are not updateable. However there are some Join Views
that are modifiable or updateable (hence “Updateable Join Views” or UJV) according to some pre-defined
criteria. These criteria can be found in the manuals here:
Oracle® Database Administrator’s Guide
10g Release 2 (10.2)
Part Number B14231-02
Chapter 20 Managing Views, Sequences, and Synonyms
“Updating a Join View”
Oracle® Database Administrator’s Guide
11g Release 1 (11.1)
Part Number B28310-04
Managing Views
“Updating a Join View”
The result of this is that if an update is made to a join view then an error such as :
ORA-01779: cannot modify a column which maps to a non keypreserved
table
Will occur. Please refer to the above manual for more details.
The Undocumented BYPASS_UJVC hint allows these checks to be bypassed and allows the update to complete,
however be aware that this is disabling checks that are there for a reason and may have unforseen
consequences. For example, if the engine is unsure regarding uniqueness of columns then the update would not
be allowed, a user however may be more sure of the data and thus be able to permit the operation in those
circumstances. As code improvements are made, more and more restrictions may be lifted.
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