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https://issues.apache.org/jira/browse/CASSANDRA-1391?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13189916#comment-13189916
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Jonathan Ellis commented on CASSANDRA-1391:
-------------------------------------------
Thanks, that helps a lot.
I think we can make life easier for clients dealing with CASSANDRA-2477 if we
split out the columns into a separate CF, and adjust how we use composites for
the columnfamilies cf:
{noformat}
schema_keyspaces
----------------
schema_keyspaces
----------------
RowKey: ks
=> (column=durable_writes, value=true, timestamp=1327061028312185000)
=> (column=name, value="ks", timestamp=1327061028312185000)
=> (column=replication_factor, value=0, timestamp=1327061028312185000)
=> (column=strategy_class,
value="org.apache.cassandra.locator.NetworkTopologyStrategy",
timestamp=1327061028312185000)
=> (column=strategy_options, value={"datacenter1":"1"},
timestamp=1327061028312185000)
schema_columnfamilies
---------------------
RowKey: ks
=> (column=cf:bloom_filter_fp_chance, value=0.0,
timestamp=1327061105833119000)
=> (column=cf:caching, value="NONE", timestamp=1327061105833119000)
=> (column=cf:column_type, value="Standard", timestamp=1327061105833119000)
=> (column=cf:comment, value="ColumnFamily", timestamp=1327061105833119000)
=> (column=cf:default_validation_class,
value="org.apache.cassandra.db.marshal.BytesType",
timestamp=1327061105833119000)
=> (column=cf:gc_grace_seconds, value=864000, timestamp=1327061105833119000)
=> (column=cf:id, value=1000, timestamp=1327061105833119000)
=> (column=cf:key_alias, value="S0VZ", timestamp=1327061105833119000)
schema_columns
--------------
RowKey: ks
=> (column=cf:c:index_name, value=null, timestamp=1327061105833119000)
=> (column=cf:c:index_options, value=null, timestamp=1327061105833119000)
=> (column=cf:c:index_type, value=null, timestamp=1327061105833119000)
=> (column=cf:c:name, value="aGVsbG8=", timestamp=1327061105833119000)
=> (column=cf:c:validation_class,
value="org.apache.cassandra.db.marshal.AsciiType",
timestamp=1327061105833119000)
{noformat}
This will be more forwards-compatible with CASSANDRA-2474/CQL 3.0, since these
correspond to tables having PRIMARY KEY (keyspace, columnfamily) and PRIMARY
KEY (keyspace, columnfamily, column), respectively.
This also has the side benefit of grouping everything for a single keyspace
under the same row key, which means it will be a single atomic RowMutation.
I think leaving strategy_options as json is fine.
> Allow Concurrent Schema Migrations
> ----------------------------------
>
> Key: CASSANDRA-1391
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1391
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 0.7.0
> Reporter: Stu Hood
> Assignee: Pavel Yaskevich
> Priority: Critical
> Fix For: 1.1
>
> Attachments: 0001-CASSANDRA-1391-main.patch,
> 0002-CASSANDRA-1391-fixes.patch, 1391-rebased.txt, CASSANDRA-1391.patch
>
>
> CASSANDRA-1292 fixed multiple migrations started from the same node to
> properly queue themselves, but it is still possible for migrations initiated
> on different nodes to conflict and leave the cluster in a bad state. Since
> the system_add/drop/rename methods are accessible directly from the client
> API, they should be completely safe for concurrent use.
> It should be possible to allow for most types of concurrent migrations by
> converting the UUID schema ID into a VersionVectorClock (as provided by
> CASSANDRA-580).
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