+ * Expected format for each key:
+ *
+ * group_by:
+ * - list of column names
+ *
+ * order:
+ * - numeric keyed column name => ASC
+ * - associative element with boolean value => DESC (true), ASC (false)
+ * - associative element with string value => 'ASC' or 'DESC' literally
+ *
+ * limit:
+ * - single numeric value => count
+ * - list with two numeric values => offset, count
+ *