On 10/11/2010 06:14 PM, Jonathan Ellis wrote:
On Mon, Oct 11, 2010 at 7:53 PM, B. Todd Burruss<[email protected]> wrote:
to determine if my programmatic schema changes have been distributed
throughout the cluster, I am supposed to use getSchemaVersionMap, correct?
my question is how do I properly use it? I have the schema version returned
from the thrift method, and I can lookup in the schema map returned
getSchemaVersionMap, but i'm not sure the proper way to interpret results.
do i wait until getSchemaVersionMap has an entry for the version in question
that contains all the nodes in my cluster?
Yes.
if this is the case, then i'm having trouble getting the number of nodes if
i have never created a keyspace. with no keyspace i can't ask for the ring,
in which case i can't count the number of nodes.
Each node can only have one active version, so the converse of "my new
version has all the nodes in the cluster" is "there are no other
versions present in the map."
i was actually doing this to start with and was worried that i could
have two clients modifying schemas at the same time. it seems this
could cause multiple valid versions and a race condition. maybe it
simply "works out" that i wait until only one version is in the map,
*if* get the version map from the same host that i used to modify the
schema?
does this make sense?
