Is Titan backward compatible?

[Roy Levin]

Hi,

I currently want to upgraded to Titan-0.5.2 (perhaps also to 0.9.0 soon as well),
however, currently my data is stored in Cassandra 1.2 which was created by Titan-0.4.4.

I tried connecting using Titan-0.5.2 but the graph seems to be empty (when I access with Titan-0.4.4 I see all the data).
Is there a way to tell Titan-0.5.2 that it is reading an older schema?

When accessing with TitanHadoop I found the following option:
titan.hadoop.input.db-version=0.4.4

However, I could not find a similar option for a standard TitanGraph.

Thanks for your help,
Roy

[Daniel Kuppitz]

Hi Roy,

please see the Upgrade Instructions.

The data storage format of Titan 0.5.0 is incompatible with previous releases.

This is still true for 0.5.1 and 0.5.2.

Cheers,

Daniel

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[Roy Levin]

Thanks Daniel -- I understand.

[pluradj]

The upgrade instructions for 0.9.0-M1 say that it is backwards compatible with 0.5.2 storage.

I loaded and committed GraphOfTheGods into an 0.5.2 keyspace, then I tried loading the same keyspace from titan-console-0.9.0-M1 and got this "StorageBackend version is incompatible with current Titan version: storage=0.5.2 vs. runtime=0.9.0-M1"

I did a bit of digging in the code and updated the top-level pom.xml with <titan.compatible.versions>0.5.2</titan.compatible.versions>. After recompiling and replacing the jars, I now get this error:

Could not deserialize to [class [Ljava.lang.String;], got: [Z@30c4e352
Display stack trace? [yN] y
java.lang.IllegalArgumentException: Could not deserialize to [class [Ljava.lang.String;], got: [Z@30c4e352
    at com.google.common.base.Preconditions.checkArgument(Preconditions.java:120)
    at com.thinkaurelius.titan.diskstorage.configuration.backend.KCVSConfiguration.staticBuffer2Object(KCVSConfiguration.java:252)
    at com.thinkaurelius.titan.diskstorage.configuration.backend.KCVSConfiguration.get(KCVSConfiguration.java:104)
    at com.thinkaurelius.titan.diskstorage.configuration.BasicConfiguration.get(BasicConfiguration.java:55)
    at com.thinkaurelius.titan.graphdb.configuration.GraphDatabaseConfiguration.<init>(GraphDatabaseConfiguration.java:1376)
    at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:91)
    at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:60)
    at com.thinkaurelius.titan.core.TitanFactory$open.call(Unknown Source)

Is there something else I can try to get backwards compatibility working?


Thanks,
Jason

[Daniel Kuppitz]

That's an error in the docs. Milestone releases are explicitly marked as incompatible with all other releases. The GA release will be backwards compatible with 0.5.x.

Cheers,

Daniel

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[pluradj]

Good to know. Thank you, Daniel!