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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-716) Re-enable VTIs
Date Fri, 04 May 2007 14:06:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12493697

Rick Hillegas commented on DERBY-716:

Thanks for helping me puzzle through the usage of VTIEnvironment, Dan. How does the following

1) Leave the VTIEnvironment arguments in the VTICosting methods.

2) Remove isCompileTime() from VTIEnvironment.

3) Beef up the javadoc for VTIEnvironment:

 a) Note that it is information used only by user-written costing logic.
 b) It allows user-written costing methods to share information with each other.
 c) Its lifetime is the lifetime of a statement plan in Derby's statement cache. If the invoking
statement has to be recompiled, then the VTIEnvironment variable can be used to share information
across re-compilations.

If we are going to use VTIEnvironment, then I think the user guides should give an example
of how to exploit this variable.

> 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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