ACCUMULO-4324 update data version

[mjwall]

This PR adds a new DATA_VERSION

[ctubbsii]

PR looks fine to me. But, for this ticket, we need to make sure upgrade from 1.6.x and upgrade from 1.7.x both work. I think they both should, since we didn't modify anything requiring additional upgrade code internally, but it'd be nice to verify. I don't think we need to support upgrades from anything older than 1.6.

[joshelser]

I think they both should, since we didn't modify anything requiring additional upgrade code internally, but it'd be nice to verify. I don't think we need to support upgrades from anything older than 1.6.

+1

[keith-turner]

I am trying to upgrade from 1.7.1 to 1.8.0-SNAPSHOT (with this commit merged into 1.8.0-SNAP). While doing this I am seeing the tserver and master fail to start with the following error. I am going to work through this.

2016-07-12 11:55:35,628 [tserver.TabletServer] ERROR: Uncaught exception in TabletServer.main, exiting
java.lang.RuntimeException: This version of accumulo (1.8.0-SNAPSHOT) is not compatible with files stored using data version 7
        at org.apache.accumulo.server.Accumulo.init(Accumulo.java:182)
        at org.apache.accumulo.tserver.TabletServer.main(TabletServer.java:2908)
        at org.apache.accumulo.tserver.TServerExecutable.execute(TServerExecutable.java:33)
        at org.apache.accumulo.start.Main$1.run(Main.java:120)
        at java.lang.Thread.run(Thread.java:745)

[keith-turner]

I added 1.7 to the set of release we can upgrade from. Probably need to remove some (like everyone that is not tested). I think we should test the upgrade from 1.6 to 1.8 and remove all other releases. Thoughts? I can take a wack at testing 1.6 to 1.8 upgrade testing, unless someone else wants to do it.

[joshelser]

1.6 and 1.7 to 1.8 sound like they should both work to me.

My gut reaction is to not worry about 1.5, but is there any fundamental problem in supporting that (is it just a testing burden)? If we don't support a direct upgrade from 1.5, what's the fail-safe? Could users just bulk-import the old files into a new instance?

[keith-turner]

My gut reaction is to not worry about 1.5, but is there any fundamental problem in supporting that (is it just a testing burden)?

Yeah its just a matter of testing it. I am not completely sure, but it seems code may be in place to support that upgrade. I don't know if it works. Personally I would not want to support it w/o testing it.

If we don't support a direct upgrade from 1.5, what's the fail-safe?

Could add support for it in 1.8.1 or later if someone really wants that functionality.

Could users just bulk-import the old files into a new instance?

That's tricky, if done incorrectly can resurrect old and/or deleted data.

Also before making any definitive decisions about 1.5 and earlier, we should see if the 1.6 to 1.8 upgrade uncovers any interesting issues.

[joshelser]

Agreed on all of your points. Want to break out things to test in a JIRA or something? I can try to help.

[keith-turner]

@mjwall I rebased this on the latest 1.8 your commit is now c8aa1fc my follow in commit to get upgrade working is a11b28b

I also squahed my commits as I made some more changes and implemented @ShawnWalker suggestion. I tested 1.6.5 to 1.8.0-SNAP and 1.7.1 to 1.8.0-SNAP upgrade .