[jira] Commented: (DERBY-716) Re-enable VTIs

["Rick Hillegas (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12476013 ] 

Rick Hillegas commented on DERBY-716:
-------------------------------------

Thanks for helping work through the details here. You are, of course, correct that the column definitions are mandatory.

I looked at the http://wiki.apache.org/db-derby/JavaTableFunctions wiki page. It seems to describe the layout and behavior of functions which return ARRAY datatypes. I do not understand how this applies to functions which return TABLE types. The SQL Standard sections on user-defined-routines are very long and, at least for me, hard to read. Still, as I read the SQL Standard, the return type of a table function is equivalent to a MULTISET datatype, not an ARRAY type. That, at least, is how I read Part 2, Section 11.50, Syntax Rule 4.

Could you point me at the chapter and verse which leads you to believe that Java TABLE functions should be implemented as ARRAY returning functions?

> Re-enable VTIs
> --------------
>
>                 Key: DERBY-716
>                 URL: https://issues.apache.org/jira/browse/DERBY-716
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Rick Hillegas
>
> Cloudscape used to expose Virtual Table Interfaces, by which any class which implemented ResultSet could be included in a query's FROM list. Derby still exposes a number of these VTIs as diagnostic tools. However, Derby now prevents customers from declaring their own VTIs. The parser raises an error if a VTI's package isn't one of the Derby diagnostic packages.
> This is a very powerful feature which customers can use to solve many problems. We should discuss the reasons that it was disabled and come up with a plan for putting this power back into our customers' hands.

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