okumin commented on code in PR #5191:
URL: https://github.com/apache/hive/pull/5191#discussion_r1565852758
##########
ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java:
##########
@@ -1736,6 +1749,13 @@ private static boolean
isWideningCast(ExprNodeGenericFuncDesc engfd) {
engfd.getTypeInfo());
}
+ private static boolean isColStatsReusableFunc(ExprNodeGenericFuncDesc engfd)
{
+ GenericUDF udf = engfd.getGenericUDF();
+ Class udfClass =
+ (udf instanceof GenericUDFBridge) ?
((GenericUDFBridge)udf).getUdfClass() : udf.getClass();
+ return udfClass == GenericUDFLower.class || udfClass ==
GenericUDFUpper.class;
Review Comment:
I like this PR. I have also observed that an estimation was wrong, and Map
Join was disabled.
We implement some estimation APIs on the UDF side. I'll share examples with
you. This is not a strong suggestion, and the current implementation seems to
be a good starting point. We may finally need a pluggable I/F to empower custom
UDFs more.
-
https://github.com/apache/hive/blob/rel/release-4.0.0/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/NDV.java
-
https://github.com/apache/hive/blob/rel/release-4.0.0/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFEvaluator.java#L63-L81
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