Author: khorgath
Date: Thu Sep 6 07:31:48 2012
New Revision: 1381489
URL: http://svn.apache.org/viewvc?rev=1381489&view=rev
Log:
HCATALOG-492 Document CTAS workaround for Hive with JSON serde (lefty via
khorgath)
Modified:
incubator/hcatalog/trunk/CHANGES.txt
incubator/hcatalog/trunk/src/docs/src/documentation/content/xdocs/supportedformats.xml
Modified: incubator/hcatalog/trunk/CHANGES.txt
URL:
http://svn.apache.org/viewvc/incubator/hcatalog/trunk/CHANGES.txt?rev=1381489&r1=1381488&r2=1381489&view=diff
==============================================================================
--- incubator/hcatalog/trunk/CHANGES.txt (original)
+++ incubator/hcatalog/trunk/CHANGES.txt Thu Sep 6 07:31:48 2012
@@ -38,6 +38,8 @@ Trunk (unreleased changes)
HCAT-427 Document storage-based authorization (lefty via gates)
IMPROVEMENTS
+ HCAT-492 Document CTAS workaround for Hive with JSON serde (lefty via
khorgath)
+
HCAT-487 HCatalog should tolerate a user-defined amount of bad records
(traviscrawford)
HCAT-488 TestHCatStorer should extend HCatBaseTest so it uses junit4 and
runs inside an IDE (traviscrawford)
Modified:
incubator/hcatalog/trunk/src/docs/src/documentation/content/xdocs/supportedformats.xml
URL:
http://svn.apache.org/viewvc/incubator/hcatalog/trunk/src/docs/src/documentation/content/xdocs/supportedformats.xml?rev=1381489&r1=1381488&r2=1381489&view=diff
==============================================================================
---
incubator/hcatalog/trunk/src/docs/src/documentation/content/xdocs/supportedformats.xml
(original)
+++
incubator/hcatalog/trunk/src/docs/src/documentation/content/xdocs/supportedformats.xml
Thu Sep 6 07:31:48 2012
@@ -26,6 +26,26 @@
<p>Users can write SerDes for custom formats using the instructions at <a
href="https://cwiki.apache.org/confluence/display/Hive/SerDe/";>https://cwiki.apache.org/confluence/display/Hive/SerDe</a>.</p>
+ <p><strong>Usage from Hive</strong></p>
+
+ <p> As of 0.4, Hive and HCatalog share the same storage abstractions, and
thus, you can read from and write to HCatalog tables from within Hive, and vice
versa.</p>
+
+ <p>However, Hive does not know where to find the HCatalog jar by default, so
if you use any features that have been introduced by HCatalog, such as a table
using the JSON SerDe, you might get a "class not found" exception.
+In this situation, before you run Hive, set environment variable
<code>HIVE_AUX_JARS_PATH</code> to the directory with your HCatalog jar.
+(If the examples in the <a href="install.html">Installation</a> document were
followed, that should be <code>/usr/local/hcat/share/hcatalog/</code>).</p>
+
+ <p><strong>CTAS Issue with JSON SerDe</strong></p>
+
+ <p>Using the Hive CREATE TABLE ... AS SELECT command with a JSON SerDe
+results in a table that has column headers such as "<code>_col0</code>",
+which can be read by HCatalog or Hive but cannot be easily read by external
users.
+To avoid this issue, create the table in two steps instead of using CTAS:</p>
+ <ol>
+ <li>CREATE TABLE ...</li>
+ <li>INSERT OVERWRITE TABLE ... SELECT ...</li>
+ </ol>
+
+ <p>See <a
href="https://issues.apache.org/jira/browse/HCATALOG-436";>HCATALOG-436</a> for
details.</p>
</body>
</document>
