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Quick and dirty SQL/JDBC implementation for Blueprints.

Written solely for the sake of it.

Warning: Current mayor caveats:

  • Munges the db schema (automatically if certain parameters are given) – don’t use this on a database not solely created for the purpose!!!
  • Does no optimisations, like property caching, whatsoever
  • Probably leaks resources
  • Untested with databases other than H2 and Postgres
  • Uses Java object serialization to store property values, so data is completely unreadable
  • Uses an rather heavyweight connection manager added when trying (unsuccessfully) to get transaction tests to pass
  • Mmmn, probably lots more I haven’t thought of…

To try this out in the Gremlin repl you need to put some jars on the Gremlin-Groovy standalone classpath:

  • blueprints-sql-graph-0.1-SNAPSHOT.jar (this thing)
  • c3p0-0.9.1.2.jar (the connection pool)
  • Your database driver, i.e. postgresql-9.1-901.jdbc4.jar, or h2.jar

If you’re using a Gremlin distribution compiled from Github, these extra jars need to be copied to:

$GREMLIN_HOME/gremlin-groovy/target/gremlin-groovy-2.4.0-SNAPSHOT-standalone/lib/

Loading a graph in the Gremlin repl:

H2 in-memory database:

gremlin> import com.tinkerpop.blueprints.impls.sql.SqlGraph
gremlin> g = new SqlGraph("org.h2.Driver", "jdbc:h2:mem:test")
gremlin> v1 = g.addVertex()
gremlin> v1.addEdge("knows", g.addVertex())
gremlin> g.commit()

Postgres:

For server DBs you first have to create an empty database, with a username/password. The graph can be loaded thusly:

gremlin> import com.tinkerpop.blueprints.impls.sql.SqlGraph
==> ...
gremlin> g = new SqlGraph("org.postgresql.Driver", "jdbc:postgresql://localhost/blueprints", "blueprints", "changeme", false)
==>sqlgraph [jdbc:postgresql://localhost/blueprints]
gremlin> g.buildSchema()
==>null

The parameters for the constructor are:

  • The driver class (driver jar must be present on classpath)
  • The JDBC url
  • Database username
  • Database password
  • Whether or not to auto-create the schema if it can’t find one already. This can be omitted for H2
    because the default is true (assumes H2 DBs are throwaway). If ‘false’ is given, the schema can be
    created with the graph.buildSchema() function.

Mysql

gremlin> import com.tinkerpop.blueprints.impls.sql.SqlGraph
==> ...
gremlin> g = new SqlGraph("com.mysql.jdbc.Driver", "jdbc:mysql://localhost/blueprints", "blueprints", "changeme", false)
==>sqlgraph [jdbc:mysql://localhost/blueprints]
gremlin> g.buildSchema()
==>null

Potential optimisations.

Currently there are no optimisations at all with regard to making retrieval smarter and faster,
but some could be interesting to implement:

  • Caching of properties
  • Deferred insertion of properties until they can be batch inserted
  • Better property serialization
  • Smart stuff with SQL generation, or something