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reference/functions/pgroonga-command.md

@@ -5,4 +5,16 @@ layout: en
 
 # `pgroonga.command` function
 
-TODO
+`pgroonga.command` function executes a [Groonga command](http://groonga.org/docs/reference/command.html) and returns the result as `text` type value.
+
+Here is `pgroonga.command` signature:
+
+```text
+pgroonga.command(command)
+```
+
+`command` is a `text` type value. `pgroonga.command` executes `command` as a Groonga command.
+
+Groonga command returns result as JSON. `pgroonga.command` returns the JSON as `text` type value. You can use [JSON functions and operations provided by PostgreSQL](http://www.postgresql.org/docs/current/static/functions-json.html) by casting the result to `json` or `jsonb` type.
+
+See also [examples in tutorial](../../tutorial/#groonga).

tutorial/index.md

@@ -427,6 +427,8 @@ SELECT * FROM products WHERE tags %% 'PostgreSQL';
 -- (2 行)
 ```
 
+{: #groonga}
+
 ## How to use Groonga throw PGroonga
 
 This is an advanced topic.
@@ -473,7 +475,7 @@ SELECT * FROM json_each(pgroonga.command('status')::json->1);
 -- (9 rows)
 ```
 
-See [pgroonga.command function](../reference/functions/pgroonga-command.html) for more details.
+See [`pgroonga.command` function](../reference/functions/pgroonga-command.html) for more details.
 
 ### `pgroonga.table_name` function