twalthr commented on a change in pull request #11170: [FLINK-16033][table-api]
Expose catalog lookup function calls in Scala's expression dsl.
URL: https://github.com/apache/flink/pull/11170#discussion_r383224973
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File path:
flink-table/flink-table-api-scala/src/main/scala/org/apache/flink/table/api/expressionDsl.scala
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@@ -1257,6 +1257,38 @@ trait ImplicitExpressionConversions {
convertArray(array)
}
+ //
----------------------------------------------------------------------------------------------
+ // Function calls
+ //
----------------------------------------------------------------------------------------------
+
+ /**
+ * A call to a function that will be looked up in a catalog. There are two
kinds of functions:
+ *
+ * - System functions - which are identified with one part names
+ * - Catalog functions - which are identified always with three parts names
+ * (catalog, database, function)
+ *
+ * Moreover each function can either be a temporary function or permanent one
+ * (which is stored in an external catalog).
+ *
+ * Based on that two properties the resolution order for looking up a
function based on
+ * the provided `functionName` is following:
Review comment:
```
Based on those two properties, the resolution order for looking up a
function based on the provided path is as follows:
```
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