hbase-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-2004) Client javadoc suggestion: add code examples about obtaining historical values
Date Mon, 23 Nov 2009 17:02:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-2004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12781475#action_12781475
] 

stack commented on HBASE-2004:
------------------------------

+1 Sounds like good idea to me.

> Client javadoc suggestion:  add code examples about obtaining historical values
> -------------------------------------------------------------------------------
>
>                 Key: HBASE-2004
>                 URL: https://issues.apache.org/jira/browse/HBASE-2004
>             Project: Hadoop HBase
>          Issue Type: Improvement
>          Components: client
>    Affects Versions: 0.20.1
>            Reporter: Doug Meil
>            Priority: Minor
>
> The implicit support HBase provides for versioning of values is very powerful, but it's
not all that obvious for application programmers to use it to obtain the historical values.
> I would like to suggest adding some comments and sample code to the Result class (org.apache.hadoop.hbase.client.Result)
Javadoc.  I know this seems sort of obvious to people that regularly use HBase, but I think
that for new folks having code examples available in Javadoc is helpful because it's "one
stop shopping" for documentation (i.e., as opposed to looking to an external writeup).  Arguably,
this type of example could also go in the HTable class javadoc.
> e.g.,....
>     HTable table = new HTable(config, "mytable");
>     Scan scan = new Scan();   // no arguments indicates will scan all rows
>     scan.setMaxVersions( 5 );         // setting this to 1 only returns current version
>     ResultScanner rs = table.getScanner(scan);
>     for (Iterator<Result> i = rs.iterator(); i.hasNext(); ) {
>     	Result r = i.next();
>         // obtains current value from 'family:column'
>     	byte b[] = r.getValue( Bytes.toBytes("family"), Bytes.toBytes("column") );
>     	KeyValue kv[] = r.raw();
>     	for (int j = 0; j < kv.length; j++) {
>     		
>                byte bv[] = kv[j].getValue();
>               // this loop returns both current and historical values
>                byte bc[] = kv[j].getColumn();
>                // returns 'family:column'
>          }
>    }    
>  

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message