Table of Contents
In order to fully maintain data integrity and ensure good transactional behavior, Neo4j supports the ACID properties:
- atomicity: If any part of a transaction fails, the database state is left unchanged.
- consistency: Any transaction will leave the database in a consistent state.
- isolation: During a transaction, modified data cannot be accessed by other operations.
- durability: The DBMS can always recover the results of a committed transaction.
Specifically:
- All database operations that access the graph, indexes, or the schema must be performed in a transaction.
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The default isolation level is
READ_COMMITTED. - Data retrieved by traversals is not protected from modification by other transactions.
- Non-repeatable reads may occur (i.e., only write locks are acquired and held until the end of the transaction).
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One can manually acquire write locks on nodes and relationships to achieve higher level of isolation (
SERIALIZABLE). - Locks are acquired at the Node and Relationship level.
- Deadlock detection is built into the core transaction management.