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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-82) [hbase] VOTE: should row keys be less restrictive than hadoop.io.Text?
Date Tue, 19 Feb 2008 18:32:43 GMT

    [ https://issues.apache.org/jira/browse/HBASE-82?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12570357#action_12570357
] 

stack commented on HBASE-82:
----------------------------

Are you referring to BasicTypeSorterBase Kevin?  I see compares of WritableComparables but
not of byte arrays (Unless you are talking of the inner Comparator class)?  Mind supplying
a pointer to where bytes are compared?

A comparator that does byte arrays will be pretty slow thinking on it; wouldn't you have to
create instances of the classes you want to compare on each invocation of the compare?  Would
that work for jaql?  This seems to be how bdbje would do it.   The objects it passes to Comparator.compare
are two byte arrays.  Then, "If you know how your data is organized in the byte  array, then
you can write a comparison routine that directly examines the contents of the arrays. Otherwise,
you have to reconstruct your original objects, and then perform the comparison. ").



> [hbase] VOTE: should row keys be less restrictive than hadoop.io.Text?
> ----------------------------------------------------------------------
>
>                 Key: HBASE-82
>                 URL: https://issues.apache.org/jira/browse/HBASE-82
>             Project: Hadoop HBase
>          Issue Type: Wish
>            Reporter: Jim Kellerman
>
> 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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