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https://issues.apache.org/jira/browse/HBASE-5104?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13177405#comment-13177405
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Kannan Muthukkaruppan commented on HBASE-5104:
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Additional note: The use of ColumnPaginationFilter AND ColumnPrefixFilter for
the intended use case (i.e. to get next set of 5 thread ids for tag2) probably
will not work even after this bug is fixed. I think once the bug is fixed for
the above data set, the program should return 0 kvs.
Here's why:
(select * from Tab where filter1 and filter2)
should be same as:
(select * from Tab where filter1) INTERSECT (select * from Tab where filter2)
When separately applied, filter1 will return rows with tag1 prefix and filter2
will return rows with tag0 prefix (for Jiakai's example above) and the
INTERSECTION will be the empty set.
The real confusion here seems to be because of the use of a filter for
pagination. This seems odd. In normal SQL for example, pagination is not part
of the WHERE clause but a separate special clause (as if it was being applied
on the results of a sub-query).
(select * from Tab
where column LIKE 'tag1%"
LIMIT 5 OFFSET 5)
Possible ways of supporting this use case:
1) Don't use AND (via FilterList), but enhance ColumnPrefixFilter to support
another constructor which supports limit/offset.
2) Support pagination (limit/offset) at the Scan/Get API level (rather than as
a filter) [Like SQL].
Thoughts?
> FilterList doesn't work right with filters (such as ColumPrefixFilter) which
> use the SEEK_NEXT_USING_HINT
> ---------------------------------------------------------------------------------------------------------
>
> Key: HBASE-5104
> URL: https://issues.apache.org/jira/browse/HBASE-5104
> Project: HBase
> Issue Type: Bug
> Reporter: Kannan Muthukkaruppan
> Assignee: Madhuwanti Vaidya
> Attachments: testFilterList.rb
>
>
> Thanks Jiakai Liu for reporting this issue and doing the initial
> investigation. Email from Jiakai below:
> Assuming that we have an index column family with the following entries:
> "tag0:001:thread1"
> ...
> "tag1:001:thread1"
> "tag1:002:thread2"
> ...
> "tag1:010:thread10"
> ...
> "tag2:001:thread1"
> "tag2:005:thread5"
> ...
> To get threads with "tag1" in range [5, 10), I tried the following code:
> ColumnPrefixFilter filter1 = new
> ColumnPrefixFilter(Bytes.toBytes("tag1"));
> ColumnPaginationFilter filter2 = new ColumnPaginationFilter(5 /* limit
> */, 5 /* offset */);
> FilterList filters = new FilterList(Operator.MUST_PASS_ALL);
> filters.addFilter(filter1);
> filters.addFilter(filter2);
> Get get = new Get(USER);
> get.addFamily(COLUMN_FAMILY);
> get.setMaxVersions(1);
> get.setFilter(filters);
> Somehow it didn't work as expected. It returned the entries as if the filter1
> were not set.
> Turns out the ColumnPrefixFilter returns SEEK_NEXT_USING_HINT in some cases.
> The FilterList filter does not handle this return code properly (treat it as
> INCLUDE).
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