Repeatable read isolation level
Repeatable read is a database transaction-isolation level that prevents a transaction from observing changes to data it has already read during that transaction.
Java Persistence with Spring Data and Hibernate epub
Repeatable read is a transaction isolation level under which repeated reads of the same data return a consistent value within a transaction, preventing unrepeatable reads while generally allowing phantom reads.
- How it is used
- Protects repeated reads within a transaction and frames the choice of database isolation for concurrent application work.
- How deep it goes
- Compares prevented anomalies, costs, and related JPA locking behavior, without specifying a database's internal isolation algorithm.
- Examples
- Uses an isolation-level comparison, a locked item-price calculation, and a MySQL JDBC setting for refresh visibility.
- What you can do after
- Operate/configure it to preserve repeated row reads and adjust isolation when refresh must see another transaction's changes.
100 SQL Server Mistakes and How to Avoid Them
Repeatable Read is a transaction isolation level that prevents dirty and nonrepeatable reads but can allow phantom reads.
- How it is used
- Guides transaction-isolation choices when preventing nonrepeatable reads matters more than permitting maximum concurrency.
- How deep it goes
- Explains dirty, nonrepeatable, and phantom reads through concurrent transactions, but stops short of implementation internals.
- Examples
- Demonstrates reporting queries and a data steward's updates or deletes against ImpressionsArchive in two query windows.
- What you can do after
- Evaluate whether Repeatable Read is necessary, then choose a weaker or stronger isolation level according to consistency and contention requirements.
Read how 100 SQL Server Mistakes and How to Avoid Them explains repeatable read isolation level →
Related concepts
- isolationkind of · Isolation is the separation of components, processes, resources, or contexts to limit interaction, interference, or the propagation of effects between them.
- nonrepeatable readaddresses · A nonrepeatable read is a concurrency anomaly in which repeated reads of the same data within a transaction return different values after another transaction modifies it.
- MySQLconfigured by · MySQL is an open-source relational database management system that stores, manages, and queries structured data using SQL.
- PESSIMISTIC_WRITEproduced by · PESSIMISTIC_WRITE is a JPA lock mode that acquires an exclusive lock, guarantees repeatable reads, and serializes conflicting data access.
- database transactionconfigures · A database transaction is a logical unit of database operations whose changes are committed together or rolled back as a whole.
- read committed isolation levelcontrasts with · A database transaction isolation level that prevents reads of uncommitted changes while allowing later reads in a transaction to observe newer committed data.
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