15.00 - 15.10 - Definition of Serializability - Teradata Database

Teradata Database Introduction to Teradata

Teradata Database
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User Guide
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English (United States)
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A set of transactions is serializable if the set produces the same result as some arbitrary serial execution of those same transactions for arbitrary input.

A set of transactions is correct only if it is serializable. The Two-Phase Locking (2PL) protocol ensures the serializability of transactions.

The phases of the Two-Phase Locking protocol are described in the following table:


In the…

A transaction must…

growing phase

acquire a lock on an object before operating on it.

The Teradata Optimizer requests locks as close to the beginning of the transaction as possible.

shrinking phase

release the previously acquired lock and never acquire any more locks after it has released a lock.

Lock release is an all‑or‑none operation. Once acquired, locks are not released until the transaction has committed or is completely rolled back.