[jira] [Updated] (CASSANDRA-6048) CQL3 data filtering improvement

["Alex Liu (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-6048?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alex Liu updated CASSANDRA-6048:
--------------------------------

    Issue Type: Improvement  (was: Bug)
    
> CQL3 data filtering improvement
> -------------------------------
>
>                 Key: CASSANDRA-6048
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6048
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Alex Liu
>
> Existing data filtering uses the following algorithm
> {code}
>    1. find best selective predicate based on the smallest mean columns count
>    2. fetch rows for the best selective predicate predicate, then filter the data based on other predicates left.
> {code}
> So potentially we could improve the performance by
> {code}
>    1.  joining multiple predicates then do the data filtering for other predicates.
>    2.  fine tune the best predicate selection algorithm
> {code}
> For multiple predicate join, it could improve performance if one predicate has many entries and another predicate has a very few of entries. It means a few index CF read, join the row keys, fetch rows then filter other predicates.

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