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From "Daniel John Debrunner (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-716) Re-enable VTIs
Date Thu, 03 May 2007 16:39:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12493419
] 

Daniel John Debrunner commented on DERBY-716:
---------------------------------------------

Why is the VTIEnvironment class being removed from the VTICosting interface? Does it cause
issues in some way?

The separation of the creation of the VTICosting object from the creation of the VTI class
means that the costing cannot take into
account the parameters being passed to the table function. Thus it might be hard for an application
developer to have any meaningful
costing information, defeating the whole purpose of the interface.

It also limits the any class to supporting just one static method that returns a ResultSet,
unless they can all share the same exact costing information.

> 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
>         Attachments: functionTables.html, functionTables.html
>
>
> 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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