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https://issues.apache.org/jira/browse/HBASE-6142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13286858#comment-13286858
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Joep Rottinghuis commented on HBASE-6142:
-----------------------------------------
Another example that requires a double-take after initial first reading:
WhileMatchFilter:
{code}
/**
* A wrapper filter that returns true from {@link #filterAllRemaining()} as soon
* as the wrapped filters {@link Filter#filterRowKey(byte[], int, int)},
* {@link Filter#filterKeyValue(org.apache.hadoop.hbase.KeyValue)},
* {@link org.apache.hadoop.hbase.filter.Filter#filterRow()} or
* {@link org.apache.hadoop.hbase.filter.Filter#filterAllRemaining()} methods
* returns true.
*/
{code}
Huh? A Filter that returns true... meaning that values will be filtered out not
pass the filter.
Seems like the point is to stop the scan after a certain condition is met for
efficiency, but it is not immediately obvious how multiple filters interact
when wrapped by WhileMatchFilter.
> Javadoc in some Filters ambiguous
> ---------------------------------
>
> Key: HBASE-6142
> URL: https://issues.apache.org/jira/browse/HBASE-6142
> Project: HBase
> Issue Type: Bug
> Components: documentation
> Affects Versions: 0.92.2, 0.96.0, 0.94.1
> Reporter: Joep Rottinghuis
> Priority: Minor
>
> The javadoc on some of the filter is somewhat confusing.
> The main Filter interface has methods that behave like a sieve; when
> filterRowKey returns true, that means that the row is filtered _out_ (not
> included).
> Many of the Filter implementations work the other way around. When the
> condition is met the value passes (ie, the row is returned).
> Most Filters make it clear when a values passes (passing through the filter
> meaning the values are returned from the scan).
> Some are less clear in light of how the Filter interface works:
> WhileMatchFilter and SingleColumnValueFilter are examples.
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