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From "Jason Altekruse (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-57) Add a logical operator that returns a constant result, similar to VALUES operator in SQL
Date Wed, 05 Jun 2013 21:01:21 GMT

    [ https://issues.apache.org/jira/browse/DRILL-57?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13676341#comment-13676341

Jason Altekruse commented on DRILL-57:

Following a short meeting about type specification in JSON I have prepared a document with
a description with some of our options and attached it to this issue. Please take a look at
it and share your opinions of the various options or suggest some improvements.
> Add a logical operator that returns a constant result, similar to VALUES operator in
> ----------------------------------------------------------------------------------------
>                 Key: DRILL-57
>                 URL: https://issues.apache.org/jira/browse/DRILL-57
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Jason Altekruse
>         Attachments: constant.patch, types_meeting_6_5_13.txt
> Add a logical operator that returns a constant result. This is necessary to be able to
create values out of thin air, if you don't know what tables exist.
> This operator is analogous to the VALUES operator in SQL. For example,
>   VALUES (1, 'a'), (2, 'b'), (3, 'c')
> returns 3 rows with 2 columns and
>   VALUES (1, 'a'), (2, 'b'), (3, 'c') AS t(c1, c2)
> allows you to name those columns "c1" and "c2". VALUES is useful for evaluating expressions
that don't belong in a table, for example
>   VALUES 10 + 3
> (Some databases would express this "SELECT 10 + 3". Same idea, and same underlying relational
> The JSON for this new operator might look like this:
> 	    {
> 	      op: "constant",
>               content: { [
>                 {c1: 1, c2: "a"},
>                 {c1: 2, c3: ["x", "y", "z"]}
>               ] }
> 	    }
> This operator is necessary in order to implement the SQL VALUES clause.

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