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From dyozie <...@git.apache.org>
Subject [GitHub] incubator-hawq-docs pull request #124: HAWQ-1435 document new pxf jdbc plug-...
Date Wed, 28 Jun 2017 16:09:46 GMT
Github user dyozie commented on a diff in the pull request:

    https://github.com/apache/incubator-hawq-docs/pull/124#discussion_r124581749
  
    --- Diff: markdown/pxf/JdbcPXF.html.md.erb ---
    @@ -0,0 +1,213 @@
    +---
    +title: Accessing External SQL Databases with JDBC (Beta)
    +---
    +
    +<!--
    +Licensed to the Apache Software Foundation (ASF) under one
    +or more contributor license agreements.  See the NOTICE file
    +distributed with this work for additional information
    +regarding copyright ownership.  The ASF licenses this file
    +to you under the Apache License, Version 2.0 (the
    +"License"); you may not use this file except in compliance
    +with the License.  You may obtain a copy of the License at
    +
    +  http://www.apache.org/licenses/LICENSE-2.0
    +
    +Unless required by applicable law or agreed to in writing,
    +software distributed under the License is distributed on an
    +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    +KIND, either express or implied.  See the License for the
    +specific language governing permissions and limitations
    +under the License.
    +-->
    +
    +Some of your data may already reside in an external SQL database. The PXF JDBC plug-in
reads data stored in SQL databases including MySQL, ORACLE, PostgreSQL, and Hive.
    +
    +This section describes how to use PXF with JDBC, including an example of creating and
querying an external table that accesses data in a MySQL database table.
    +
    +## <a id="jdbcplugin_prereq"></a>Prerequisites
    +
    +Before accessing external SQL databases using HAWQ and PXF, ensure that:
    +
    +-   The JDBC plug-in is installed on all cluster nodes. See [Installing PXF Plug-ins](InstallPXFPlugins.html)
for PXF plug-in installation information.
    +-   The JDBC driver JAR files for the external SQL database are installed on all cluster
nodes.
    +-   The file locations of external SQL database JDBC JAR files are added to `pxf-public.classpath`.
If you manage your HAWQ cluster with Ambari, add the JARS via the Ambari UI. If you managed
your cluster from the command line, edit the `/etc/pxf/conf/pxf-public.classpath` file directly.
    +
    +
    +## <a id="hdfsplugin_queryextdata"></a>Querying External SQL Data
    +The PXF JDBC plug-in supports the single profile named `Jdbc`.
    +
    +Use the following syntax to create a HAWQ external table representing external SQL database
tables you access via JDBC: 
    +
    +``` sql
    +CREATE [READABLE | WRITABLE] EXTERNAL TABLE <table_name>
    +    ( <column_name> <data_type> [, ...] | LIKE <other_table> )
    +LOCATION ('pxf://<host>[:<port>]/<jdbc-schema-name>.<jdbc-database-name>.<jdbc-table-name>
    +    ?PROFILE=Jdbc[&<custom-option>=<value>[...]]')
    +FORMAT 'CUSTOM' (FORMATTER='pxfwritable_import');
    +```
    +
    +JDBC-plug-in-specific keywords and values used in the [CREATE EXTERNAL TABLE](../reference/sql/CREATE-EXTERNAL-TABLE.html)
call are described in the table below.
    +
    +| Keyword  | Value |
    +|-------|-------------------------------------|
    +| \<column-name\>    | The name of the PXF external table column. The PXF \<column-name\>
must exactly match the \<column-name\> used in the external SQL table.|
    +| \<data-type\>    | The data type of the PXF external table column. The PXF \<data-type\>
must be equivalent to the data type used for \<column-name\> in the SQL table.|
    +| \<host\>    | The PXF host. While \<host\> may identify any PXF agent node,
use the HDFS NameNode as it is guaranteed to be available in a running HDFS cluster. If HDFS
High Availability is enabled, \<host\> must identify the HDFS NameService. |
    +| \<port\>    | The PXF port. If \<port\> is omitted, PXF assumes \<host\>
identifies a High Availability HDFS Nameservice and connects to the port number designated
by the `pxf_service_port` server configuration parameter value. Default is 51200. |
    +| \<jdbc-schema-name\>    | The schema name. The default schema name is `default`.
|
    +| \<jdbc-database-name\>    | The database name. The default database name is determined
by the external SQL server. |
    +| \<jdbc-table-name\>    | The table name. |
    +| PROFILE    | The `PROFILE` keyword must specify `Jdbc`. |
    +| \<custom-option\>  | The custom options supported by the `Jdbc` profile are discussed
later in this section.|
    +| FORMAT 'CUSTOM' | The JDBC `CUSTOM` `FORMAT` supports only the built-in `'pxfwritable_import'`
`FORMATTER` property. |
    +
    +*Note*: When creating PXF external tables, you cannot use the `HEADER` option in your
`FORMAT` specification.
    --- End diff --
    
    Extremely minor, but "Note:" here should be bolded:  **Note:**


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