[jira] [Commented] (DRILL-57) Add a logical operator that returns a constant result, similar to VALUES operator in SQL

["Michael Hausenblas (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-57?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13633942#comment-13633942 ] 

Michael Hausenblas commented on DRILL-57:
-----------------------------------------

OK, so I took that over. Though I *think* I know the current codebase I'd appreciate directions where and how to start this.
                
> Add a logical operator that returns a constant result, similar to VALUES operator in SQL
> ----------------------------------------------------------------------------------------
>
>                 Key: DRILL-57
>                 URL: https://issues.apache.org/jira/browse/DRILL-57
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Michael Hausenblas
>
> 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 2 rows with 3 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 operator.)
> 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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