Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/819#discussion_r113915026
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillOptiq.java
---
@@ -512,9 +511,9 @@ public LogicalExpression visitLiteral(RexLiteral
literal) {
return ValueExpressions.getBit(((Boolean) literal.getValue()));
case CHAR:
if (isLiteralNull(literal)) {
- return createNullExpr(MinorType.VARCHAR);
+ return createStringNullExpr(literal.getType().getPrecision());
--- End diff --
The length is 4, we treat it as regular string. If customer wants to treat
such literals as actual null value, then he needs to handle such case in sql
code. For example, `select case when col = 'NULL' then cast(null as varchar(10)
else col end from t`. Converting 'NULL' string to null value implicitly may not
be a good idea, since we don't know how users wants us to treat such literals.
I think it's ok if user will handle such cases by himself.
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