Josh Rosen created SPARK-15764:
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Summary: Replace n^2 loop in BindReferences
Key: SPARK-15764
URL: https://issues.apache.org/jira/browse/SPARK-15764
Project: Spark
Issue Type: Improvement
Components: SQL
Reporter: Josh Rosen
Assignee: Josh Rosen
BindReferences contains a n^2 loop which causes performance issues when
operating over large schemas: to determine the ordinal of an input, we perform
a linear scan over the {{input}} array. Because {{input}} can sometimes be a
List, the call to {{input(ordinal).nullable}} can also be O(n).
Instead of performing a linear scan, we can convert the input into an array and
build a hash map to map from expression ids to ordinals. The greater up-front
cost of the map construction is offset by the fact that an expression can
contain multiple attribute references, so the cost of the map construction is
amortized across a number of lookups.
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