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Databases & SQL vocabulary · Transactions and Concurrency

Isolation level

Meaning in databases & SQL, with examples

nounAdvanced term

In databases & SQL, isolation level means: A setting that controls how much one transaction can see of other transactions' changes, trading data safety against speed and concurrency.

In Turkish: yalıtım düzeyi, izolasyon seviyesi

How it is used

The SQL standard defines four: READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ and SERIALIZABLE. Lower levels allow problems such as dirty reads and phantom reads. PostgreSQL and SQL Server default to READ COMMITTED; MySQL InnoDB defaults to REPEATABLE READ.

Example sentences

  1. We raised the isolation level to SERIALIZABLE for the seat booking transaction.

  2. What is the default isolation level in MySQL, and why does it matter for this bug?

Common collocations

  • set the isolation level
  • transaction isolation level
  • READ COMMITTED
  • dirty read
  • SERIALIZABLE
  • transactionA group of database operations that are treated as one unit: either all of them succeed together or none of them is applied.
  • ACIDAtomicity, Consistency, Isolation, Durability: the four guarantees that make database transactions reliable even with errors, crashes and many users at once.
  • lockA mark the database places on a row, page or table so that other transactions cannot change it, or sometimes read it, until the current transaction ends.
  • deadlockA situation where two or more transactions each wait for a lock the other holds, so none of them can continue until the database cancels one.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Transactions and Concurrency

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