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https://issues.apache.org/jira/browse/PHOENIX-1826?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Taylor updated PHOENIX-1826:
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Attachment: PHOENIX-1826.patch
[~maryannxue] - would you mind reviewing this patch. Main changes are:
- re-implement order preserving tracker in OrderPreservingTracker using
Expression visitor instead of parse node visitor. See one workaround noted in
code there for UNION ALL.
- as a result, use order of GROUP BY expressions as tie-breaker for order of
expressions to form group by key(this facilitated a number of changes in the
explain plan tests).
- this fixes numerous bugs in tracking whether or not order is preserved
- also uncovered an optimization to not do the client-side sort in a DISTINCT
or GROUP BY query if we're ordering in the same way that ORDER BY is ordering
(this facilitated a number of changes in the explain plan tests). Note that we
could do more here - order the GROUP BY to match the ORDER BY, for example.
> Implement TrackOrderPreservingExpressionCompiler as Expression visitor
> instead of ParseNode visitor
> ---------------------------------------------------------------------------------------------------
>
> Key: PHOENIX-1826
> URL: https://issues.apache.org/jira/browse/PHOENIX-1826
> Project: Phoenix
> Issue Type: Task
> Reporter: James Taylor
> Attachments: PHOENIX-1826.patch
>
>
> We currently traverse the ORDER BY ParseNodes in
> TrackOrderPreservingExpressionCompiler to determine if the rows will be
> ordered in row key order. This complicates supporting ORDER BY expressions
> that are an ordinal position (PHOENIX-1749), since it's a fair bit of code to
> manufacture a ParseNode when wildcards are used in the select. We should
> consider writing this visitor as an Expression instead and then using ordinal
> position would be easy as we could index into the RowProjector to get an
> Expression. See ViewWhereExpressionVisitor in CreateTableCompiler for an
> example.
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