Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/685#discussion_r98186438
--- 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 --
Each drill function is converted to DrillFunctionHolder and though Calcite
recognizes current_time/current_date & other context functions (ex: user,
current_schema) as niladic, after introduction of isNilladic flag,
DrillFunctionHolder would describe such functions as non-niladic, though they
are. So we are intentionally hold incorrect info.
Let's say in future I would need to take list of all function holders in
Drill (form local function registry) and filter out all niladic functions,
since we do have such isNiladic flag I would assume that I can use this flag as
filter but since current_time/current_date & other context functions (ex: user,
current_schema) have isniladic=false, they would never be filtered out.
Also please add `isNiladic=true` to other niladic context functions [1].
[1]
https://github.com/apache/drill/blob/5a4ad2a88331dfe7561ee76fc87e882afe170681/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/ContextFunctions.java
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
