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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 Fri, 15 Feb 2008 17:38:07 GMT

    [ https://issues.apache.org/jira/browse/HBASE-82?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12569335#action_12569335

stack commented on HBASE-82:

Couple of comments:

+ Extending comment 08/Jan/08 11:18 AM above (how to prevent user entering different key types),
since columns have no types in hbase and column family is the lowest level of granularity
on which we can set attributes, this would imply that the key type would need to be an attribute
of column family.  An attempt at adding a key that was of a different type should throw an
exception (As MR input types do)?
+ I like byte arrays for keys.  Aligns w/ a notion I have that hbase should be as dumb as
possible, but no dumber -- as Einstein said once?  I like the reminder that this is how bdb
does it.  Would it work?  For jaql?  Client-side, they'd pass a byte array for row key.  
Internally we'd just be be doing byte compares (Though I think thats all we're currently doing
with our Text keys).
+ ImmutableByteArray is already a WritableCompable

> [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
> 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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