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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1531) Add RowFilter to HRegion.HScanner
Date Tue, 03 Jul 2007 17:31:04 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1531?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12509948
] 

stack commented on HADOOP-1531:
-------------------------------

Regards the filterAllRemaining above, I should add another version of the regex filter if
I just want a scanner to return me all row keys that match apache.com (and that gives up scanning
once it leaves row keys that contain that domain)?  Thanks for setting me right on final(Text,
Text, byte []) . In RegExpRowFilter.filter(Text), its returning true if the regex matches.
 Shouldn't that be inverted?

Regards export of my eclipse format, I would not inflict my settings on others.  I loose interest
configuring eclipse after about the tenth dialog box so at a minimum they are incomplete.
  IIRC, others have posted 'hadoop' eclipse formatters to the mailing list.

On wrapping after the operator, it does not appear as an option in the eclipse formatter tablet
(I'm looking at an eclipse 3.3).  it always wants to wrap before. Odd, because if you use
eclipse to break a long string, it leaves the '+' as the last character on the wrapped line
(which is what I want).  Hanging operators when wrapping a line as an indicator of continuation
I first read of in 'Java Elements of Style' I believe.  It made sense to me.

> Add RowFilter to HRegion.HScanner
> ---------------------------------
>
>                 Key: HADOOP-1531
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1531
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: contrib/hbase
>    Affects Versions: 0.14.0
>            Reporter: James Kennedy
>            Assignee: James Kennedy
>         Attachments: eclipse.preferences, RowFilter-v2.patch, RowFilter-v3.patch, RowFilter.patch
>
>
> I've implemented a RowFilterInterface and a RowFilter implementation.  This is passed
to the HRegion.HScanner via HClient.openScanner() though it is an entirely optional parameter.
> HScanner applies the filter in the next() call by iterating until it encounters a row
that is not filtered by the RowFilter.  The filter applies criteria based on row keys and/or
column data values.
> Null values are little tricky since the resultSet in that loop may represent nulls as
absent columns or as DELETED_BYTES.  Nevertheless null cases are taken care of by the filter
and you can for example retrieve all rows where column X = null.
> The initial RowFilter implementation is limited in several ways:
> * Equality test only with literal values. No !=, <, >, etc. No col1 == col2. This
is a straight-up byte[] comparison.
> * Multiple column criteria are treated as an implicit conjunction, no disjunction possible.
> * row key criteria is a regular expression only
> * row key criteria is independent of column criteria. No "if rowkey.matches(A)  and col1==B"
 although the interface is created to allow for that.
> But it should be easy to write an improved RowFilterInterface implementation to take
care of most of the above without having to change code elsewhere.

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