KazydubB commented on a change in pull request #1870: DRILL-7359: Add support
for DICT type in RowSet Framework
URL: https://github.com/apache/drill/pull/1870#discussion_r361603427
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/resultSet/impl/ColumnBuilder.java
##########
@@ -179,6 +189,19 @@ private ColumnState buildPrimitive(ContainerState parent,
ColumnReadProjection c
vectorState);
}
+ /**
+ * Check if this is a special case when vector, writer and column state
should be
+ * created for a primitive field though the field itself is not projected.
This is
+ * needed because {@code DICT}'s {@code keys} field is not projected but is
needed
+ * to be initialized to ensure the dict vector is constructed properly.
Review comment:
Oops, my bad - hasn't mentioned (just a kind of implicit hint in the
`@return`) in the javadoc body (do not know what is the text before `@param`,
`@return` etc. is called) that this affects creation of `DICT`'s `key` when
`value` is accessed by key only, i.e. `col['someKey']` with `col` being a
`DICT` column with `String` (`VARCHAR`) `key`; `value` in this case will be
projected.
If the `DICT` is not projected, this won't create any vector: neither
`DictVector` nor vector for `key` (or `value`) - special "dummy" vector for
`DICT` will be used, as is done for other vectors.
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