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https://issues.apache.org/jira/browse/DRILL-5830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16198755#comment-16198755
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ASF GitHub Bot commented on DRILL-5830:
---------------------------------------
Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/968#discussion_r143714717
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/record/RecordBatchLoader.java
---
@@ -150,6 +162,40 @@ public boolean load(RecordBatchDef def, DrillBuf buf)
throws SchemaChangeExcepti
return schemaChanged;
}
+ private boolean checkMapSchema(Collection<MaterializedField>
currentChildren,
--- End diff --
May be we can rename method? At least for me under `checkMapSchema` is not
quite obvious that we will be comparing two schemas and return true if two maps
are the same (comments inside of the method were helpful though).
> 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.
> As it turns out, HBase already had a project push-down rule that expanded
> wildcards. However, that rule didn't work correctly some of the time.
> DRILL-5546 fixed that bug, ensuring that wildcards are expanded (at least in
> the cases tested for this ticket.)
> The actual issue turned out to be a bug in the {{RecordBatchLoader}} class
> which did not consider map contents when detecting schema change. As a
> result, results like (row_key, cf\{}) were treated the same as (row_key,
> cf\{mycol}) and the actual data colums were discarded, but randomly depending
> on batch arrival order.
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