GitHub user sounakr opened a pull request:
https://github.com/apache/incubator-carbondata/pull/878 Like Filter Pushdown
Problem : Like filter Pushdown.
Analysis : Filter Predicates with Like expression are converted to StartWith or EndsWith expression in spark. But the expression with StartsWith can be converted to LessThan and GreaterThan Expression which can furthur boil down to Range Filter Optimization.
For e.g.
select * from t1 where empid like '1%';
spark filter => StartsWith(empid, '1')
carbon filter => empid GreaterThanEqual Expression '1'
empid LessThan Expression '2'
carbon range opt => Range Filters Conversion i.e. single expression '1' <= empid < '2'
Fix: a) Push Down Like Filters
b) Avoid Row Level Evaluation in case Filter predicates on No Dictionary Greater Than and Less Than Expression.
You can merge this pull request into a Git repository by running:
$ git pull
https://github.com/sounakr/incubator-carbondata like_pushdown
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-carbondata/pull/878.patchTo close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #878
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commit 8d40084ed62fe70ea099aeca3184347d2cd993b0
Author: sounakr <
[hidden email]>
Date: 2017-05-04T04:46:19Z
Like Filter Pushdown
No Dictionary Handling in Greater and Less Than Expression
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