Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/819#discussion_r113606129
--- Diff: common/src/main/java/org/apache/drill/common/types/Types.java ---
@@ -636,43 +658,63 @@ public static String toString(final MajorType type) {
/**
* Get the <code>precision</code> of given type.
- * @param majorType
- * @return
+ *
+ * @param majorType major type
+ * @return precision value
*/
public static int getPrecision(MajorType majorType) {
- MinorType type = majorType.getMinorType();
-
- if (type == MinorType.VARBINARY || type == MinorType.VARCHAR) {
- return 65536;
- }
-
if (majorType.hasPrecision()) {
return majorType.getPrecision();
}
- return 0;
+ return isScalarStringType(majorType) ? MAX_VARCHAR_LENGTH : UNDEFINED;
--- End diff --
Drill loves to compute things, such as widths, based on metadata. But,
Drill is... schemaless! That means that we don't generally have metadata. As a
result, we have to compute things based on made-up numbers, as we are doing
here.
If we want to tell the client the actual sizes, we should sample the first
batch of data. See `RecordBatchSizer` that computes average column width from
data. Of course, you want maximum width, which is more costly to compute.
---
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.
---
