tsreaper commented on a change in pull request #16420:
URL: https://github.com/apache/flink/pull/16420#discussion_r666636299
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File path:
flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/planner/codegen/GenerateUtils.scala
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@@ -176,7 +184,15 @@ object GenerateUtils {
val resultTerm = ctx.addReusableLocalVariable(resultTypeTerm, "result")
val isResultNullable = resultNullable || (isReference(returnType) &&
!isTemporal(returnType))
val nullTermCode = if (ctx.nullCheck && isResultNullable) {
- s"$nullTerm = ($resultTerm == null);"
+ // we assume that result term of a primitive SQL type will never be null,
+ // violating this assumption might cause null pointer exception
somewhere else.
+ // when using this column we'll first check its null term.
+ s"""
+ |$nullTerm = ($resultTerm == null);
Review comment:
Indeed. I used to think that this change will only affect non-primitive
numbers and booleans. However string is also a non-primitive type so this
change might affect a larger scope than I thought.
I once also thought of checking null terms when generating filter code,
however this will affect almost all generated code which I also think is not
efficient.
Currently I can't come up with other places where null terms aren't checked
before result terms are used. So I'd like to only change the
`GeneratedExpression` produced by casting to boolean.
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