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https://issues.apache.org/jira/browse/PIG-4953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15384612#comment-15384612
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Ryan Blue commented on PIG-4953:
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[~daijy], can you take a look at this patch?
This fixes the visit method and adds tests for predicate push-down. I noticed
that the tests added with PIG-4940 were for partition push-down, not predicate.
I copied the test file and modified it to use
{{PredicatePushDownFilterExtractor}}. I also added a test for PIG-4940 and for
this. The successful case caught an additional problem: the fix for PIG-4940
didn't remove the residual filters that accumulate on the filter plan when the
entire unary expression is going to be added to the filter plan isntead. I
fixed this case and the tests are passing. I'd appreciate it if the reviewers
could check that I got the logic right here. I'm not very familiar with how
residuals are handled and want to make sure this is correct. Thanks!
> Predicate push-down will not run filters for single unary expressions
> ---------------------------------------------------------------------
>
> Key: PIG-4953
> URL: https://issues.apache.org/jira/browse/PIG-4953
> Project: Pig
> Issue Type: Bug
> Components: impl
> Affects Versions: 0.15.0
> Reporter: Ryan Blue
> Assignee: Ryan Blue
> Attachments: PIG-4953.1.patch
>
>
> While testing PIG-4940, I noticed that a "is not null" predicate was not
> pushed down, but equality predicates were. The problem is that the
> {{FilterExtractor#visit}} method ignores anything that isn't a
> {{BinaryExpression}}. Pushing down {{UnaryExpression}} filters works if the
> expression is linked in by a binary expression, like "b is not null and c ==
> 'val'".
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