arina-ielchiieva commented on a change in pull request #1690: DRILL-7086:
Output schema for row set mechanism
URL: https://github.com/apache/drill/pull/1690#discussion_r264648930
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/rowSet/impl/OptionBuilder.java
##########
@@ -129,10 +133,60 @@ public OptionBuilder setSchema(TupleMetadata schema) {
return this;
}
+ /**
+ * Provide an optional column conversion factory. Can create a "shim"
+ * writer to convert from a type convenient for the client to the type
+ * required by the vector. Example: string-to-int conversion. The factory
+ * can inspect column metadata properties to decide what conversion, if
+ * any, to create.
+ * <p>
+ * A column conversion factory assumes that the data type of the output
+ * vector is the same as the data type of the column schema passed to
+ * the result set loader. It does allow inserting a type conversion or
+ * validation shim above the column writer specified by the column
+ * type.
+ * <p>
+ * The result set loader makes no assumptions about how the conversion
+ * factory works. It can follow the Drill schema definition patterns, or
+ * it could do something ad-hoc: such details are hidden inside the
+ * implementation.
+ * <p>
+ * Provide either a (lower-level) column conversion factory or a
+ * (higher level) column transformer, but not both. This form is used
+ * mostly for testing, but could also be used by operators other than
+ * scan,.
Review comment:
```suggestion
* scan.
```
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