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exec/java-exec/src/main/java/org/apache/drill/exec/resolver/TypeCastRules.java <https://reviews.apache.org/r/20742/#comment76102> Here we use an identical value, if the function requires a secondary implicit cast for one of its argument. This will make the code unable to differentiate the matching of other arguments. Let's say we have function implementation: func (varchar, int) func (varchar, float4) Now, if we have a function : func(123, 8.0). For the two function implementations, the code will return the same cost, since both of them requires secondary implicit cast. Which function holder will be picked will probably depends on the order that the code adds the function holder into registry. That is, we probably need still add the cost for other arguments to the total cost, so that we know which function holder is the best match. - Jinfeng Ni On April 26, 2014, 12:40 a.m., Mehant Baid wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/20742/ > ----------------------------------------------------------- > > (Updated April 26, 2014, 12:40 a.m.) > > > Review request for drill, Jacques Nadeau and Jinfeng Ni. > > > Bugs: DRILL-577 > https://issues.apache.org/jira/browse/DRILL-577 > > > Repository: drill-git > > > Description > ------- > > 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 > ----- > > > 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 > ------- > > Added test to check that implicit cast works both ways. > > 8 + '2' > substr(10123, 1, 3) > > > Thanks, > > Mehant Baid > >
