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From "Carl Yeksigian (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-6477) Global indexes
Date Mon, 04 May 2015 14:05:11 GMT


Carl Yeksigian commented on CASSANDRA-6477:

# It is going to be the same mechanism, but we don't want to use the same consistency as what
the insert is. This way, we can ensure that at least one node has seen all of the updates,
and thus we can generate the correct tombstone based on the previous values
# Each replica makes a GI update independently, based on the data that it has, which means
that we might issue updates for an older update that hasn't made it to all of the replicas
yet. To cut down on the amount of work that the indexes do, a pretty easy optimization is
to just send the index mutation to the index replica that the data node will wait on instead
of sending them to all of the index replicas
# If we ever get into a situation where we have data loss in either the base table or the
index table (both would likely go together), we would really need to run a rebuild, since
there is no guarantee that extra data wouldn't be present in the index which isn't in the
data table. Otherwise, we can repair the data and index tables independently, so that a repair
issued on the data table should also repair all of the global index tables

> Global indexes
> --------------
>                 Key: CASSANDRA-6477
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>            Assignee: Carl Yeksigian
>              Labels: cql
>             Fix For: 3.x
> Local indexes are suitable for low-cardinality data, where spreading the index across
the cluster is a Good Thing.  However, for high-cardinality data, local indexes require querying
most nodes in the cluster even if only a handful of rows is returned.

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