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https://issues.apache.org/jira/browse/FLINK-5752?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15980983#comment-15980983
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ASF GitHub Bot commented on FLINK-5752:
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GitHub user ramkrish86 opened a pull request:
https://github.com/apache/flink/pull/3760
FLINK-5752 Support push down projections for HBaseTableSource (Ram)
Ran mvn clean verify -DskipTests
In this patch
`Arrays.sort(nestedFields[i]);`
Am doing this before doing addColumns for the new projected table source,
because here the cols appears in a reverse sorted way and when we apply that
for the new projected table source it creates an assertion error while creating
the new calcite program with the projected cols
`assert expr.getType().getFieldList().get(field.getIndex()) == field;`
So doing this sort helps in correcting those issues and the tests run fine.
But this nestedFields that is being passed to the projectNestedFields() API is
created by
`def getProjectedFields: Array[Array[String]] ` under RexProgramExtractor.
Trying to understand what it does.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ramkrish86/flink FLINK-5752
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/3760.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #3760
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commit 1885b0c9afc7aa49747987b0508ba82002a1bc8d
Author: Ramkrishna <[email protected]>
Date: 2017-04-24T10:23:08Z
FLINK-5752 Support push down projections for HBaseTableSource (Ram)
----
> Support push down projections for HBaseTableSource
> --------------------------------------------------
>
> Key: FLINK-5752
> URL: https://issues.apache.org/jira/browse/FLINK-5752
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
>
> This is after the discussion to create NestedProjectableTableSource.
> Currently we support nested schema for the non-relational type of DBs like
> HBase.
> But this does not allow push down projection. This JIRA is to implement that.
> Once FLINK-5698 is implemented then we should be making use of the feature to
> push down the projections for a nested table. So in case of HBase if we have
> {f1:{a, b}, f2:{c, d}} as the nested structure then if we have a scan query
> that needs to select f2.c - then we should be specifically able to project
> only that column 'c' under 'f2'. FLINK-5698 plans to add a new API for such
> projections and HBaseTableSource should make use of that API to do the
> projection.
> [~fhueske], [~tonycox], [~jark]
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