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https://issues.apache.org/jira/browse/DRILL-5830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16186768#comment-16186768
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Paul Rogers edited comment on DRILL-5830 at 9/30/17 1:10 AM:
-------------------------------------------------------------
DRILL-5706 described a problem that we tried to fix with DRILL-5546. However,
the problem was not in the HBase storage plugin at all; instead it is in the
unordered receiver (see DRILL-5826.)
Empty regions have the schema (row_key, cf\{}) where cf is a column family.
Non-empty regions have the schema (row_key, cf\{e0}) where e0 is a column
within cf. The unordered receiver treated these schemas as identical, removing
the e0 column if it sees the empty batch first.
By fixing the unordered receiver, the original HBase problem disappears because
the rest of the code now properly handles the empty batches produced by empty
regions. That is, the other fixes from DRILL-5546 already solved the issue; we
didn't need to change HBase for a solution; instead we just needed to add one
more fix for the unordered receiver.
(Note that all receivers would have the same issue and the fix in DRILL-5826
will address all receivers.
was (Author: paul.rogers):
DRILL-5706 described a problem that we tried to fix with DRILL-5546. However,
the problem was not in the HBase storage plugin at all; instead it is in the
unordered receiver (see DRILL-5826.)
Empty regions have the schema (row_key, cf{}) where cf is a column family.
Non-empty regions have the schema (row_key, cf{e0}) where e0 is a column within
cf. The unordered receiver treated these schemas as identical, removing the e0
column if it sees the empty batch first.
By fixing the unordered receiver, the original HBase problem disappears because
the rest of the code now properly handles the empty batches produced by empty
regions. That is, the other fixes from DRILL-5546 already solved the issue; we
didn't need to change HBase for a solution; instead we just needed to add one
more fix for the unordered receiver.
(Note that all receivers would have the same issue and the fix in DRILL-5826
will address all receivers.
> Resolve regressions to MapR DB from DRILL-5546
> ----------------------------------------------
>
> Key: DRILL-5830
> URL: https://issues.apache.org/jira/browse/DRILL-5830
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.12.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Fix For: 1.12.0
>
>
> DRILL-5546 added a number of fixes for empty batches. One part of the fix was
> for HBase. Key changes:
> * Add code to expand wildcards in the planner. (i.e. SELECT *)
> * Remove support for wildcards in the HBase record reader.
> As noted in DRILL-5775, this change had the effect of breaking support for
> MapR-DB binary (which is API compatible with HBase.) DRILL-5775 does this by
> expanding wildcards in the planner for MapR DB as was done for HBase in
> DRILL-5546.
> Unfortunately, this change introduced other regressions into the code as
> described by DRILL-5706.
> Investigation of those issues revealed that we should back out the original
> DRILL-5546 changes and go down a different route.
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