Await schema agreement post migration

[mmatczuk]

This requires a patch to gocql. Gocql has a function awaitSchemaAgreement to wait for schema to be propagated to all the nodes. We should export that to Session. When done we should call it post each migration.

[dahankzter]

So the normal notification flow here isn't enough? Is it just too slow to pick up on that?

[mmatczuk]

Waiting for keyspace changed events will not work, for instance if you only add data there is not keyspace change.

[powerman]

Is there any workaround which can be used right now?

[mmatczuk]

Yes use a single host to run all the migrations. You can check that by issuing describe schema queries to different hosts.

[annismckenzie]

I'm working on this in #133. Still working out the kinks (gocql test suite is failing for some combinations on Travis, incidentally only those that have auth enabled – weird).

[mmatczuk]

Kudos for working on it.

[mmatczuk]

Fixed in #133