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https://issues.apache.org/jira/browse/PHOENIX-953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14709203#comment-14709203
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Maryann Xue commented on PHOENIX-953:
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Sure, [~jamestaylor]. The v4 patch actually had the @Ignore tag.
[~ram_krish] Yes, correct. Both UnnestArrayElemRefExpression and
UnnestArrayElemIndexExpression are only used by UnnestArrayResultIterator at
runtime, so we don't have to care about visit and serialization for these two
expressions. By having these two expressions, we can use the TupleProjector
methods directly without having to copy its implementation code here in the
iterator. Another reason is that I'd like avoid evaluating the arrayExpression
every time we get the next element from the array, and that we only need to
create one or two Expression instances during the whole iteration.
> 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
> Attachments: PHOENIX-953-v1.patch, PHOENIX-953-v2.patch,
> PHOENIX-953-v3.patch, PHOENIX-953-v4.patch
>
>
> 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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