Write skew is a phenomenon in database systems where concurrent transactions, which individually appear to maintain consistency, result in an inconsistent state when combined. This occurs in scenarios where transactions read overlapping data and then perform writes that do not directly conflict, leading to violations of expected invariants under weaker isolation levels like snapshot isolation.

Write Skew

Write skew

phenomenon in database systems

concurrent transactions

Data consistency ensures that data remains accurate and reliable across a system, preventing discrepancies and errors during data processing and retrieval. It is crucial for maintaining data integrity, especially in distributed systems where multiple sources may update the same data concurrently.

Data Consistency

inconsistent state

overlapping data

perform writes

directly conflict

expected invariants

weaker isolation levels

Snapshot Isolation is a concurrency control mechanism used in database systems to ensure transactions operate on a consistent snapshot of the database, preventing issues like dirty reads and non-repeatable reads. It allows multiple transactions to execute concurrently by providing each transaction with its own view of the database at a specific point in time, thus improving performance while maintaining data consistency.

snapshot isolation

Relevant Degrees

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