[SPARK-23812][SQL] DFS should be removed from unsupportedHiveNativeCommands in SqlBase.g4

[wangtao605]

What changes were proposed in this pull request?

Dfs command has been supported，but SqlBase.g4 also put it in unsupportedHiveNativeCommands.

(Please fill in changes proposed in this fix)

How was this patch tested?

manual tests

Please review http://spark.apache.org/contributing.html before opening a pull request.

[hvanhovell]

@wangtao605 AFAIK we don’t support dfs.

[wangtao605]

@hvanhovell Please see the pic above，i run the "DFS" command in spark-sql，it can work.

[srowen]

It may happen to work, but I think the idea here is that we do not want to guarantee it will going forward. I think this should be closed

[AmplabJenkins]

Can one of the admins verify this patch?

[wangyum]

We don’t support dfs.

scala> spark.sql("dfs -ls /tmp").show
org.apache.spark.sql.catalyst.parser.ParseException:
mismatched input 'dfs' expecting {'(', 'SELECT', 'FROM', 'ADD', 'DESC', 'WITH', 'VALUES', 'CREATE', 'TABLE', 'INSERT', 'DELETE', 'DESCRIBE', 'EXPLAIN', 'SHOW', 'USE', 'DROP', 'ALTER', 'MAP', 'SET', 'RESET', 'START', 'COMMIT', 'ROLLBACK', 'REDUCE', 'REFRESH', 'CLEAR', 'CACHE', 'UNCACHE', 'TRUNCATE', 'ANALYZE', 'LIST', 'REVOKE', 'GRANT', 'LOCK', 'UNLOCK', 'MSCK', 'EXPORT', 'IMPORT', 'LOAD'}(line 1, pos 0)

== SQL ==
dfs -ls /tmp
^^^

  at org.apache.spark.sql.catalyst.parser.ParseException.withCommand(ParseDriver.scala:239)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parse(ParseDriver.scala:115)
  at org.apache.spark.sql.execution.SparkSqlParser.parse(SparkSqlParser.scala:48)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parsePlan(ParseDriver.scala:69)
  at org.apache.spark.sql.SparkSession.sql(SparkSession.scala:638)
  ... 49 elided

bin/spark-sql uses Hive api.