Is Titan backward compatible?

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Roy Levin

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Dec 9, 2014, 10:14:41 AM12/9/14
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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

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Dec 9, 2014, 7:47:17 PM12/9/14
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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

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Dec 11, 2014, 2:14:31 AM12/11/14
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Thanks Daniel -- I understand.

pluradj

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Dec 19, 2014, 3:30:34 PM12/19/14
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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

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Dec 19, 2014, 5:23:32 PM12/19/14
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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


pluradj

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Dec 19, 2014, 5:57:34 PM12/19/14
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Good to know. Thank you, Daniel!
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