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https://issues.apache.org/jira/browse/HBASE-9717?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13787531#comment-13787531
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Mathias Herberts commented on HBASE-9717:
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I think the best way to be backward compatible would be to add two methods
Filter, namely:
abstract boolean hasRowKeyHint()
abstract byte[] getRowKeyHint(byte[] buffer, int offset, int length)
if hasRowKeyHint returns true for the filter, then when filterRowKey returns
true (filter the row), getRowKeyHint would be called and return a hint onto
which key we should seek to, or null if no hint is available.
Default implementation of hasRowKeyHint would return false.
Default implementation of getRowKeyHint would return null.
This would allow for minimal changes, basically if I'm not mistaken, Filter,
FilterBase, HRegion, FilterList, and WhileMatchFilter would be the only classes
needing changes, with a semantic to determine for FilterList in case
MUST_PASS_ONE is used.
> 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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