Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/12460#discussion_r60175987
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/SparkSqlParser.scala ---
@@ -254,6 +251,21 @@ class SparkSqlAstBuilder extends AstBuilder {
}
}
+ /**
+ * A column path can be specified as an parameter to describe command.
It is a dot separated
+ * elements where the last element can be a String.
+ * TODO - check with Herman
--- End diff --
It is a bit more complicates than I thought. We allow strings here because
Hive allows us to use the `'$elem'`, `'$keys'` and `'$values'` 'keywords'. That
is why I added strings to the rule. I am not sure if we should support this.
What do you guys think?
This is what I found in the Hive manual:
```SQL
DESCRIBE [EXTENDED|FORMATTED] [db_name.]table_name[ col_name (
[.field_name] | [.'$elem$'] | [.'$key$'] | [.'$value$'] )* ];
```
See also:
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-Describe
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