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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2334) [hbase] VOTE: should row keys be less restrictive than hadoop.io.Text?
Date Tue, 08 Jan 2008 19:19:34 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2334?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12556984#action_12556984
] 

stack commented on HADOOP-2334:
-------------------------------

Chatting with Dave Simpson, to protect against different clients inserting rows of different
types all into the one table producing an undefined sort order because of the hodge-podge
of type comparators, the key type for a table should be defined as part of table creation
with an illegal type exception thrown if a client tries an update with a non-matching type.

> [hbase] VOTE: should row keys be less restrictive than hadoop.io.Text?
> ----------------------------------------------------------------------
>
>                 Key: HADOOP-2334
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2334
>             Project: Hadoop
>          Issue Type: Wish
>          Components: contrib/hbase
>    Affects Versions: 0.16.0
>            Reporter: Jim Kellerman
>            Assignee: Jim Kellerman
>            Priority: Minor
>             Fix For: 0.16.0
>
>
> I have heard from several people that row keys in HBase should be less restricted than
hadoop.io.Text.
> What do you think?
> At the very least, a row key has to be a WritableComparable. This would lead to the most
general case being either hadoop.io.BytesWritable or hbase.io.ImmutableBytesWritable. The
primary difference between these two classes is that hadoop.io.BytesWritable by default allocates
100 bytes and if you do not pay attention to the length, (BytesWritable.getSize()), converting
a String to a BytesWritable and vice versa can become problematic. 
> hbase.io.ImmutableBytesWritable, in contrast only allocates as many bytes as you pass
in and then does not allow the size to be changed.
> If we were to change from Text to a non-text key, my preference would be for ImmutableBytesWritable,
because it has a fixed size once set, and operations like get, etc do not have to something
like System.arrayCopy where you specify the number of bytes to copy.
> Your comments, questions are welcome on this issue. If we receive enough feedback that
Text is too restrictive, we are willing to change it, but we need to hear what would be the
most useful thing to change it to as well.

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