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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6477) Global indexes
Date Mon, 20 Apr 2015 21:32:05 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14503698#comment-14503698
] 

Jonathan Ellis commented on CASSANDRA-6477:
-------------------------------------------

I'm warming up to the idea of calling it MV but only IF we're committed to fleshing it out
to match SELECT.

To start that can match our current envisioned functionality:

CREATE MATERIALIZED VIEW users_by_age AS
SELECT age, user_id, x, y, z FROM users
PRIMARY KEY (age, user_id)

but next we need to add support for WHERE and UDF:

CREATE MATERIALIZED VIEW users_by_age AS
SELECT age, user_id, substring(phone_number, 3) AS area_code, y, z FROM users
WHERE area_code in (512, 513, 514)
PRIMARY KEY (age, user_id)

Building the view should take advantage of local indexes where applicable.

Ideally we would support aggregation in MV as well.  Not sure if that is feasible.

> Global indexes
> --------------
>
>                 Key: CASSANDRA-6477
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6477
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>            Assignee: Carl Yeksigian
>              Labels: cql
>             Fix For: 3.0
>
>
> 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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