HIVE-2822 [jira] Add JSON output to the hive ddl commands

(Chris Dean via Ashutosh Chauhan)

Summary:
JSON output for DDL commands

By setting the variable hive.format=json then ddl commands will
produce json output suitable for client side parsing.  For example, to
list all the databases one might get:

    {
      "databases": [
        "default"
      ]
    }

The goal is to have an option to produce JSON output of the DDL commands that is
easily machine parseable.

For example, "desc my_table" currently gives

    id    bigint
    user  string

and we want to allow a json output:

    {
      "columns": [
        {"name": "id", "type": "bigint"},
        {"name": "user", "type": "string"}
      ]
    }

Test Plan: Run the provided unit tests

Reviewers: JIRA, ashutoshc

Reviewed By: ashutoshc

Differential Revision: https://reviews.facebook.net/D2475

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1309666 13f79535-47bb-0310-9956-ffa450edef68

common/src/java/org/apache/hadoop/hive/conf/HiveConf.java

@@ -582,6 +582,7 @@ public static enum ConfVars {
     // A comma separated list of hooks which implement HiveDriverRunHook and will be run at the
     // beginning and end of Driver.run, these will be run in the order specified
     HIVE_DRIVER_RUN_HOOKS("hive.exec.driver.run.hooks", ""),
+    HIVE_DDL_OUTPUT_FORMAT("hive.ddl.output.format", null),
     ;
 
     public final String varname;

conf/hive-default.xml.template

@@ -1259,4 +1259,13 @@
   </description>
 </property>
 
+<property>
+  <name>hive.ddl.output.format</name>
+  <value>text</value>
+  <description>
+    The data format to use for DDL output.  One of "text" (for human
+    readable text) or "json" (for a json object).
+  </description>
+</property>
+
 </configuration>