Github user nagarajanchinnasamy commented on a diff in the pull request:
https://github.com/apache/drill/pull/685#discussion_r97721703
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ContextFunctions.java
---
@@ -64,17 +65,45 @@ public void eval() {
@Inject DrillBuf buffer;
@Workspace int currentSchemaBytesLength;
+ @Override
public void setup() {
final byte[] currentSchemaBytes =
contextInfo.getCurrentDefaultSchema().getBytes();
buffer = buffer.reallocIfNeeded(currentSchemaBytes.length);
currentSchemaBytesLength= currentSchemaBytes.length;
buffer.setBytes(0, currentSchemaBytes);
}
+ @Override
public void eval() {
out.start = 0;
out.end = currentSchemaBytesLength;
out.buffer = buffer;
}
}
+
+ /**
+ * Implement "session_id" function. Returns the unique id of the current
session.
+ */
+ @FunctionTemplate(name = "session_id", scope =
FunctionTemplate.FunctionScope.SIMPLE, isNiladic = true)
--- End diff --
- Functions like current_time/current_date already function like niladic as
Calcite recognizes them so.
- IsNiladic flag can be set by any UDF. Not restricted only to session_I'd
- If I understand right, currently there is no categorization of UDFs in
Drill. If we want to restrict isNiladic flag only to a particular category of
UDFs, then categorization of UDFs need to be designed n implemented.
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