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Message Posted: Mon, 06 Apr 2015 @ 16:46:15 GMT


     
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Subj:   Re: Updating via view concurrently
 
From:   frank.c.martinez

Uh, no, if you do LOCKING ROW .. FOR ACCESS, you get a dirty read on a PI (or equivalent has collisions). The following section of the manual might help:

Using LOCKING ROW Note that LOCKING ROW does not generally lock a single row, but rather all rows that hash to a specific value. It is a row hash lock, not a row lock.

The LOCKING ROW modifier cannot be used to lock multiple row-hashes. If you specify LOCKING ROW FOR ACCESS with multiple row-hashes, the lock is converted to LOCKING TABLE FOR ACCESS, but a WRITE or EXCLUSIVE row-hash lock severity is not transferred to a table-level lock. If a LOCKING ROW FOR WRITE severity is not applicable, the default table-level lock severity is maintained.

A single value in an IN clause is accepted as a valid row-hash lock specification.

The use of LOCKING ROW prevents possible deadlocks occurring when two simultaneous primary index SELECTs are followed by an UPDATE, DELETE, or INSERT on the same row.


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