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https://issues.apache.org/jira/browse/SPARK-10978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14998883#comment-14998883
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Yin Huai commented on SPARK-10978:
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I am not sure {{partiallyHandledFilters}} is really useful. I mean a filter is
either evaluated for every rows in the data source or not evaluated for every
row (it is possible that the data source does not support filter pushdown or
the data source only has corse-grained index). So, as long as we know this
information, we can make decision on if we should add spark-sql side filter.
For our internal data sources, I think it is fine to let unhandledFilters just
return all filters because it is not really expensive to re-evaluate them.
> Allow PrunedFilterScan to eliminate predicates from further evaluation
> ----------------------------------------------------------------------
>
> Key: SPARK-10978
> URL: https://issues.apache.org/jira/browse/SPARK-10978
> Project: Spark
> Issue Type: New Feature
> Components: SQL
> Affects Versions: 1.3.0, 1.4.0, 1.5.0
> Reporter: Russell Alexander Spitzer
> Assignee: Cheng Lian
> Priority: Critical
> Fix For: 1.6.0
>
>
> Currently PrunedFilterScan allows implementors to push down predicates to an
> underlying datasource. This is done solely as an optimization as the
> predicate will be reapplied on the Spark side as well. This allows for
> bloom-filter like operations but ends up doing a redundant scan for those
> sources which can do accurate pushdowns.
> In addition it makes it difficult for underlying sources to accept queries
> which reference non-existent to provide ancillary function. In our case we
> allow a solr query to be passed in via a non-existent solr_query column.
> Since this column is not returned when Spark does a filter on "solr_query"
> nothing passes.
> Suggestion on the ML from [~marmbrus]
> {quote}
> We have to try and maintain binary compatibility here, so probably the
> easiest thing to do here would be to add a method to the class. Perhaps
> something like:
> def unhandledFilters(filters: Array[Filter]): Array[Filter] = filters
> By default, this could return all filters so behavior would remain the same,
> but specific implementations could override it. There is still a chance that
> this would conflict with existing methods, but hopefully that would not be a
> problem in practice.
> {quote}
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