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From dyozie <...@git.apache.org>
Subject [GitHub] incubator-hawq-docs pull request #46: HAWQ-1119 - create doc content for PXF...
Date Mon, 31 Oct 2016 22:25:50 GMT
Github user dyozie commented on a diff in the pull request:

    --- Diff: pxf/HDFSWritablePXF.html.md.erb ---
    @@ -0,0 +1,410 @@
    +title: Writing Data to HDFS
    +The PXF HDFS plug-in supports writable external tables using the `HdfsTextSimple` and
`SequenceWritable` profiles.  You might create a writable table to export data from a HAWQ
internal table to HDFS.
    +This section describes how to use these PXF profiles to create writable external tables.
    +**Note**: You cannot directly query data in a HAWQ writable table.  After creating the
external writable table, you must create a HAWQ readable external table accessing the HDFS
file, then query that table. ??You can also create a Hive table to access the HDFS file.??
    +## <a id="pxfwrite_prereq"></a>Prerequisites
    +Before working with HDFS file data using HAWQ and PXF, ensure that:
    +-   The HDFS plug-in is installed on all cluster nodes. See [Installing PXF Plug-ins](InstallPXFPlugins.html)
for PXF plug-in installation information.
    +-   All HDFS users have read permissions to HDFS services and that write permissions
have been restricted to specific users.
    +## <a id="hdfsplugin_writeextdata"></a>Writing to PXF External Tables
    +The PXF HDFS plug-in supports writable two profiles: `HdfsTextSimple` and `SequenceWritable`.
    +Use the following syntax to create a HAWQ external writable table representing HDFS data: 
    +``` sql
    +    ( <column_name> <data_type> [, ...] | LIKE <other_table> )
    +LOCATION ('pxf://<host>[:<port>]/<path-to-hdfs-file>
    +    ?PROFILE=HdfsTextSimple|SequenceWritable[&<custom-option>=<value>[...]]')
    +FORMAT '[TEXT|CSV|CUSTOM]' (<formatting-properties>);
    +HDFS-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 |
    +| \<host\>[:\<port\>]    | The HDFS NameNode and port. |
    +| \<path-to-hdfs-file\>    | The path to the file in the HDFS data store. |
    +| PROFILE    | The `PROFILE` keyword must specify one of the values `HdfsTextSimple`
or `SequenceWritable`. |
    +| \<custom-option\>  | \<custom-option\> is profile-specific. These options
are discussed in the next topic.|
    +| FORMAT 'TEXT' | Use '`TEXT`' `FORMAT` with the `HdfsTextSimple` profile when \<path-to-hdfs-file\>
will reference a plain text delimited file. The `HdfsTextSimple` '`TEXT`' `FORMAT` supports
only the built-in `(delimiter=<delim>)` \<formatting-property\>. |
    +| FORMAT 'CSV' | Use '`CSV`' `FORMAT` with `HdfsTextSimple` when \<path-to-hdfs-file\>
will reference a comma-separated value file.  |
    +| FORMAT 'CUSTOM' | Use the `'CUSTOM'` `FORMAT` with the `SequenceWritable` profile.
The `SequenceWritable` '`CUSTOM`' `FORMAT` supports only the built-in `(formatter='pxfwritable_export)`
(write) and `(formatter='pxfwritable_import)` (read) \<formatting-properties\>.
    +**Note**: When creating PXF external tables, you cannot use the `HEADER` option in your
`FORMAT` specification.
    +## <a id="profile_hdfstextsimple"></a>Custom Options
    +The `HdfsTextSimple` and `SequenceWritable` profiles support the following \<custom-options\>:
    --- End diff --
    Change <custom-options> to "<custom-option> values"?

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