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Data & Analytics · Advanced

Snapshot Isolation

An isolation level in which each transaction reads a consistent snapshot of the data as of its start, using row versions.

Definition

Snapshot isolation avoids read locks, so readers and writers don't block each other, and it detects write-write conflicts at commit. It can still allow anomalies such as write skew, so it is not fully serializable.

Example

SET TRANSACTION ISOLATION LEVEL SNAPSHOT;

Exam tip

Snapshot isolation avoids blocking but can fail with update conflicts; handle retries.

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