hawq-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
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:

    https://github.com/apache/incubator-hawq-docs/pull/46#discussion_r85794241
  
    --- 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
    +CREATE EXTERNAL WRITABLE TABLE <table_name> 
    +    ( <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"?


---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastructure@apache.org or file a JIRA ticket
with INFRA.
---

Mime
View raw message