Database Reference
In-Depth Information
When a data modification begins, it will either start with a new transaction or run within a transaction that
already exists. If a transaction does not exist in the current operation, Cypher will create one and commit it once the
query finishes. When a transaction is available within the current operation, the query will run inside that transaction
and the success of entire transaction determines whether any data will be committed. Of course, it is sometimes
necessary to add multiple queries within a single transaction, as follows:
1.
Start a new transaction
2.
Add the Cypher queries
3.
Commit the transaction
a query will hold the changes in memory until the whole query has finished executing. a large query will consequently
need a JVM with lots of heap space.
Compatibility
Neo4j is a stable, proven database option and supports mission-critical applications for companies big and small, but
new features will be blended in over time. As Neo4j evolves, the Cypher language will evolve as well. The development
team working on Neo4j, specifically on Cypher, is mindful of adding new syntax or modifying existing syntax to ensure
minimal disruption in the application lifecycle. To that end, configuration options enable support of different
Cypher versions.
■
Note
Throughout this topic, {NeO4J_rOOT} refers to the top-level installation directory for Neo4j.
To configure a specific Cypher version for use throughout an entire Neo4j system, you can modify a line within the
{NEO4J_ROOT}/conf/neo4j.properties configuration file and specify the version you prefer as shown in Listing 4-1.
Listing 4-1.
Explicitly Setting the Cypher Version in the Neo4j Configuration Properties
# Enable this to specify a parser other than the default one.
# cypher_parser_version=2.0
To enable a specific version on a case-by-case basis or to override a specific parser version, you can add the
version number to your Cypher query, as shown in Listing 4-2.
Listing 4-2.
Specifying the Cypher Version in a Cypher Query
CYPHER 1.9 START person=node(0)
WHERE person.name="Greg"
RETURN person
