Github user fmcquillan99 commented on a diff in the pull request:
https://github.com/apache/madlib/pull/239#discussion_r172920581
--- Diff: src/ports/postgres/modules/sample/balance_sample.sql_in ---
@@ -149,8 +149,10 @@ non-stratified, that is, the whole table is treated as
a
single group.
@note
-Current implementation does not support grouping_cols. It
-will be added in an upcoming release.
+The 'output_table_size' and the 'class_sizes' are defined for the whole
table.
+When grouping is used, these parameters are split evenly for each group.
+Further, if a specific class value is specified in the 'class_sizes'
parameter,
+that particular class value should be present in each group.
</dd>
--- End diff --
Please change/add:
"...that particular class value should be present in each group."
to
"...that particular class value should be present in each group. If not,
an error will be thrown."
---
