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Committed Read Isolation Level

Committed Read Isolation Level

Question:
I’ve written several dynamic queries in VB importing a recordset from an Informix DB. The isolation level shows “Committed Read.” Does this place locks on the DB?

Answer:
Committed Read isolation guarantees your application that it will never return a row that has not been committed to the database. The read does not actually place a lock on the fetched row. Rather, it first checks for the existence of an UPDATE lock for any pending updates on that row. If there’s no lock, the query returns the row. If there’s a lock, it is not returned. This is almost as efficient as the dirty read isolation, but if you’re having concurrency problems I’d move it down to DIRTY READ and see if that solves them.

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