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https://issues.apache.org/jira/browse/HADOOP-1531?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12508648
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James Kennedy commented on HADOOP-1531:
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in relation to Hadoop-1439, i'll add a comment there.
I think i needed that RowFilter() constructor to make RPC serialization happy.
Needs to instantiate the filter before it calls readFields().
The regexp is passed to the constructor since its a single param whereas the
column criteria is many. I suppose i could add a constructor that takes a list
of col criteria.
filter subpackage is a good idea... in fact it wouldn't hurt to refactor whats
there into some other sub-packages.
is the filter == null code necessary? I thought I saw RPC code that was
handling nulls. Indeed in my testing i seem to be able to pass null filters
through rpc just fine. I'll dbl check that though.
and I'll fix the other stuff you guys mentioned.
> 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: 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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