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https://issues.apache.org/jira/browse/PHOENIX-953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14654752#comment-14654752
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Maryann Xue commented on PHOENIX-953:
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Yes, the very fundamental thing we need for unnest is an
UnnestArrayResultIterator (maybe as an inner class of UnnestArrayQueryPlan),
which takes an array and emits a new tuple for each of the array's element.
The UnnestArrayQueryPlan may derive from DelegateQueryPlan, which has an input
plan. For example, "select unnest(array1) from t", we'll get a ScanPlan on
table 't' wrapped by an UnnestArrayQueryPlan.
I just implemented the extension for VALUES
(https://docs.oracle.com/javadb/10.8.3.0/devguide/cdevtricks807365.html) on the
calcite branch and committed a new class called LiteralResultIterationQueryPlan
(which is an enhanced version of EmptyTableQueryPlan). I think this should be
helpful for the "no from clause UNNEST" and might be exactly what it needs.
> Support UNNEST for ARRAY
> ------------------------
>
> Key: PHOENIX-953
> URL: https://issues.apache.org/jira/browse/PHOENIX-953
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: James Taylor
> Assignee: Dumindu Buddhika
>
> The UNNEST built-in function converts an array into a set of rows. This is
> more than a built-in function, so should be considered an advanced project.
> For an example, see the following Postgres documentation:
> http://www.postgresql.org/docs/8.4/static/functions-array.html
> http://www.anicehumble.com/2011/07/postgresql-unnest-function-do-many.html
> http://tech.valgog.com/2010/05/merging-and-manipulating-arrays-in.html
> So the UNNEST is a way of converting an array to a flattened "table" which
> can then be filtered on, ordered, grouped, etc.
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