First draft of Mongodb plugin

pom.xml

@@ -83,6 +83,7 @@
         <module>presto-base-jdbc</module>
         <module>presto-mysql</module>
         <module>presto-postgresql</module>
+        <module>presto-mongodb</module>
         <module>presto-client</module>
         <module>presto-parser</module>
         <module>presto-main</module>

presto-docs/src/main/sphinx/connector.rst

@@ -14,6 +14,7 @@ from different data sources.
     connector/jmx
     connector/kafka
     connector/kafka-tutorial
+    connector/mongodb
     connector/mysql
     connector/postgresql
     connector/redis

presto-docs/src/main/sphinx/connector/mongodb.rst

@@ -0,0 +1,244 @@
+=================
+MongoDB Connector
+=================
+
+This connector allows the use of Mongodb collections as tables in Presto.
+
+.. note::
+
+    Mongodb 2.6+ is supported although it is highly recommend to use 3.0 or later.
+
+Configuration
+-------------
+
+To configure the MongoDB connector, create a catalog properties file
+``etc/catalog/mongodb.properties`` with the following contents,
+replacing the properties as appropriate:
+
+.. code-block:: none
+
+    connector.name=mongodb
+    mongodb.seeds=host1,host:port
+
+Multiple MongoDB Clusters
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You can have as many catalogs as you need, so if you have additional
+MongoDB clusters, simply add another properties file to ``etc/catalog``
+with a different name (making sure it ends in ``.properties``). For
+example, if you name the property file ``sales.properties``, Presto
+will create a catalog named ``sales`` using the configured connector.
+
+Configuration Properties
+------------------------
+
+The following configuration properties are available:
+
+===================================== ==============================================================
+Property Name                         Description
+===================================== ==============================================================
+``mongodb.seeds``                     List of all mongod servers
+``mongodb.schema-collection``         A collection which contains schema information
+``mongodb.credentials``               List of credentials
+``mongodb.min-connections-per-host``  The minimum size of the connection pool per host
+``mongodb.connections-per-host``      The maximum size of the connection pool per host
+``mongodb.max-wait-time``             The maximum wait time
+``mongodb.connection-timeout``        The socket connect timeout
+``mongodb.socket-timeout``            The socket timeout
+``mongodb.socket-keep-alive``         Whether keep-alive is enabled on each socket
+``mongodb.read-preference``           The read preference
+``mongodb.write-concern``             The write concern
+``mongodb.required-replica-set``      The required replica set name
+``mongodb.cursor-batch-size``         The number of elements to return in a batch
+===================================== ==============================================================
+
+``Mongodb.seeds``
+^^^^^^^^^^^^^^^^^
+
+Comma-separated list of ``hostname[:port]`` all mongod servers in the same replica set or a list of mongos servers in the same sharded cluster. If port is not specified, port 27017 will be used.
+
+This property is required; there is no default and at least one seed must be defined.
+
+``mongodb.schema-collection``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+As the MongoDB is a document database, there's no fixed schema information in the system. So a special collection in each MongoDB database should defines the schema of all tables. Please refer the :ref:`table-definition-label` section for the details.
+
+At startup, this plugin tries guessin fields' types, but it might not be correct for your collection. In that case, you need to modify it manually. ``CREATE TABLE`` and ``CREATE TABLE AS SELECT`` will create an entry for you.
+
+This property is optional; the default is ``_schema``.
+
+``mongodb.credentials``
+^^^^^^^^^^^^^^^^^^^^^^^
+
+A comma separated list of ``username:password@collection`` credentials
+
+This property is optional; no default value
+
+``mongodb.min-connections-per-host``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The minimum number of connections per host for this MongoClient instance. Those connections will be kept in a pool when idle, and the pool will ensure over time that it contains at least this minimum number.
+
+This property is optional; the default is ``0``.
+
+``mongodb.connections-per-host``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The maximum number of connections allowed per host for this MongoClient instance. Those connections will be kept in a pool when idle. Once the pool is exhausted, any operation requiring a connection will block waiting for an available connection.
+
+This property is optional; the default is ``100``.
+
+``mongodb.max-wait-time``
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The maximum wait time in milliseconds that a thread may wait for a connection to become available.
+A value of 0 means that it will not wait. A negative value means to wait indefinitely for a connection to become available.
+
+This property is optional; the default is ``120000``.
+
+``mongodb.connection-timeout``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The connection timeout in milliseconds. A value of 0 means no timeout. It is used solely when establishing a new connection Socket.connect(java.net.SocketAddress, int)
+
+This property is optional; the default is ``10000``.
+
+``mongodb.socket-timeout``
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The socket timeout in milliseconds. It is used for I/O socket read and write operations Socket.setSoTimeout(int)
+
+This property is optional; the default is ``0`` and means no timeout.
+
+``mongodb.socket-keep-alive``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This flag controls the socket keep alive feature that keeps a connection alive through firewalls Socket.setKeepAlive(boolean)
+
+This property is optional; the default is ``false``.
+
+``mongodb.read-preference``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The read preference to use for queries, map-reduce, aggregation, and count. The available values are PRIMARY, PRIMARY_PREFERRED, SECONDARY, SECONDARY_PREFERRED and NEAREST.
+
+This property is optional; the default is ``PRIMARY``.
+
+``mongodb.write-concern``
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The write concern to use. The available values are ACKNOWLEDGED, FSYNC_SAFE, FSYNCED, JOURNAL_SAFEY, JOURNALED, MAJORITY, NORMAL, REPLICA_ACKNOWLEDGED , REPLICAS_SAFE and UNACKNOWLEDGED.
+
+This property is optional; the default is ``ACKNOWLEDGED``.
+
+``mongodb.required-replica-set``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The required replica set name. With this option set, the MongoClient instance will
+
+#. Connect in replica set mode, and discover all members of the set based on the given servers
+#. Make sure that the set name reported by all members matches the required set name.
+#. Refuse to service any requests if any member of the seed list is not part of a replica set with the required name.
+
+This property is optional; no default value
+
+``mongodb.required-replica-set``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Limits the number of elements returned in one batch. A cursor typically fetches a batch of result objects and stores them locally.
+If batchSize is 0, Driver's default will be used.
+If batchSize is positive, it represents the size of each batch of objects retrieved. It can be adjusted to optimize performance and limit data transfer.
+If batchSize is negative, it will limit of number objects returned, that fit within the max batch size limit (usually 4MB), and cursor will be closed. For example if batchSize is -10, then the server will return a maximum of 10 documents and as many as can fit in 4MB, then close the cursor.
+
+.. note::
+    Do not use a batch size of 1.
+
+This property is optional; the default is ``0``.
+
+.. _table-definition-label:
+
+Table Definition
+----------------
+
+MongoDB maintains table definitions on the special collection where ``mongodb.schema-collection`` configuration value specifies.
+
+.. note::
+    There's no way for the plugin to detect a collection is deleted.
+    You need to delete the entry by ``db.getCollection("_schema").remove( { table: deleted_table_name })`` at the Mongo Shell. Or please drop a collection by ``drop table table_name`` at Presto shell.
+
+A schema collection consists of a MongoDB document for a table.
+
+.. code-block:: json
+
+    {
+        "table": ...,
+        "fields": [
+              { "name" : ...,
+                "type" : "varchar|bigint|boolean|double|date|array<bigint>|...",
+                "hidden" : false },
+                ...
+            ]
+        }
+    }
+
+=============== ========= ============== =============================
+Field           Required  Type           Description
+=============== ========= ============== =============================
+``table``       required  string         Presto table name
+``fields``      required  array          A list of field definitions. Each field definition creates a new column in the Presto table.
+=============== ========= ============== =============================
+
+Each field definition:
+
+.. code-block:: json
+
+    {
+        "name": ...,
+        "type": ...,
+        "hidden": ...
+    }
+
+=============== ========= ========= =============================
+Field           Required  Type      Description
+=============== ========= ========= =============================
+``name``        required  string    Name of the column in the Presto table.
+``type``        required  string    Presto type of the column.
+``hidden``      optional  boolean   Hides the column from ``DESCRIBE <table name>`` and ``SELECT *``. Defaults to ``false``.
+=============== ========= ========= =============================
+
+There is no limit on field descriptions for either key or message.
+
+ObjectId
+--------
+MongoDB collection has the special filed ``_id``. The plugin tries to follow the same rules for this special field, so there will be hidden field ``_id``.
+
+
+.. code-block:: sql
+
+    CREATE TABLE IF NOT EXISTS orders (
+        orderkey bigint,
+        orderstatus varchar,
+        totalprice double,
+        orderdate date
+    );
+
+    insert into orders values( 1, 'bad', 50.0, current_date);
+    insert into orders values( 2, 'good', 100.0, current_date);
+    select _id, * from orders3;
+
+                     _id                 | orderkey | orderstatus | totalprice | orderdate
+    -------------------------------------+----------+-------------+------------+------------
+     55 b1 51 63 38 64 d6 43 8c 61 a9 ce |        1 | bad         |       50.0 | 2015-07-23
+     55 b1 51 67 38 64 d6 43 8c 61 a9 cf |        2 | good        |      100.0 | 2015-07-23
+     (2 rows)
+
+     select _id, * from orders3 where _id = ObjectId('55b151633864d6438c61a9ce');
+
+                     _id                 | orderkey | orderstatus | totalprice | orderdate
+    -------------------------------------+----------+-------------+------------+------------
+     55 b1 51 63 38 64 d6 43 8c 61 a9 ce |        1 | bad         |       50.0 | 2015-07-23
+     (1 row)
+
+.. note::
+    Unfortunately there's no way to represent _id field more fancy like `55b151633864d6438c61a9ce`