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https://reviews.apache.org/r/20742/
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Review request for drill, Jacques Nadeau and Jinfeng Ni.
Bugs: DRILL-577
https://issues.apache.org/jira/browse/DRILL-577
Repository: drill-git
Description
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Currently implicit cast works as per the precedence rules. However based on
some functions it might be useful allow the implicit cast to work in the
opposite direction as specified by the precedence map.
For example: As per the precedence rules, we can implicitly cast from VARCHAR
---> BIGINT. However for some functions (eg: substr, concat) it might be useful
to implicitly cast from BIGINT ---> VARCHAR.
ResolverTypePrecedence.java:
Added a new set of secondary rules that allow for implicit cast to work in the
other direction. Currently these secondary set of rules only allow to cast to
VARCHAR, so we don't have cost, if we add more rules here we can add cost to
determine which cast function to pick.
ExpressionTreeMaterializer.java:
Fixed bug in visitFunctionCall() that does not add an argument(length) while
casting to variable width types
TypeCastRules.java
Added logic to see if we can apply implicit cast based on the secondary rules
while matching a given call to a DrillFuncHolder.
Diffs
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exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java
a602d82
exec/java-exec/src/main/java/org/apache/drill/exec/resolver/ResolverTypePrecedence.java
f6d83e2
exec/java-exec/src/main/java/org/apache/drill/exec/resolver/TypeCastRules.java
3aab08f
exec/java-exec/src/test/java/org/apache/drill/exec/physical/impl/TestReverseImplicitCast.java
PRE-CREATION
exec/java-exec/src/test/resources/functions/cast/two_way_implicit_cast.json
PRE-CREATION
Diff: https://reviews.apache.org/r/20742/diff/
Testing
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Added test to check that implicit cast works both ways.
8 + '2'
substr(10123, 1, 3)
Thanks,
Mehant Baid
