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From "Mathias Herberts (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9717) Allow filterRowKey to return a next key hint
Date Mon, 07 Oct 2013 05:22:57 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9717?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13787911#comment-13787911

Mathias Herberts commented on HBASE-9717:

If decision of skipping or including a whole row on the row key alone can be made, doesn't
it imply a performance hit to implement the filter so the filtering is done in filterKeyValue
instead of filterRowKey? In case of skipping a row the performance might be very similar,
but when including a row doesn't this mean filterKeyValue will be called for each cell (since
filterKeyValue does not have a INCLUDE_ALL_ROW return code).

Also (I have not digged sufficiently in the code yet), doesn't filterRowKey imply that only
the row key will be read in memory instead of an entire cell?

> Allow filterRowKey to return a next key hint
> --------------------------------------------
>                 Key: HBASE-9717
>                 URL: https://issues.apache.org/jira/browse/HBASE-9717
>             Project: HBase
>          Issue Type: New Feature
>          Components: Filters
>            Reporter: Mathias Herberts
> The Filter interface has a filterRowKey method which returns a boolean set to true if
the given row key should be filtered out.
> When a row key is filtered, it could be interesting to be able to provide the scanner
a hint about the next row key which should be examined. This could tremendously speed up scanning
in some cases.
> The logic could be similar to that of filterKeyValue with a helper method getNextRowKeyHint,
or even simpler, filterRowKey could return a byte[] which would be set to null to mean keep
the row, to the empty array to mean filter the row and there is not hint, and to a non empty
byte array to mean filter the row and here is a hint about the next key that should be scanned.

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