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Posted to commits@cassandra.apache.org by "Alex Liu (JIRA)" <ji...@apache.org> on 2013/09/18 00:05:52 UTC
[jira] [Created] (CASSANDRA-6048) CQL3 data filtering improvement
Alex Liu created CASSANDRA-6048:
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Summary: CQL3 data filtering improvement
Key: CASSANDRA-6048
URL: https://issues.apache.org/jira/browse/CASSANDRA-6048
Project: Cassandra
Issue Type: Bug
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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