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https://issues.apache.org/jira/browse/DERBY-6036?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13547178#comment-13547178
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Rick Hillegas commented on DERBY-6036:
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I have verified that there is no special jiggery-pokery to reduce the number of
columns read from the base table when it is wrapped in a view. For the SELECT
from the view (select s_nr from vt where ns_r = 3000), the whole row is read
from the Store.
Fixing this performance problem may be a little tricky. The ProjectRestrict
nodes are added by the optimizer AFTER the bind-phase has expanded the * in the
view and concluded that ALL of the columns are being referenced.
> If you wrap a view around a RestrictedVTI, the projection is not pushed into
> the table function.
> ------------------------------------------------------------------------------------------------
>
> Key: DERBY-6036
> URL: https://issues.apache.org/jira/browse/DERBY-6036
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.10.0.0
> Reporter: Rick Hillegas
> Attachments: derby-6036.sql, derbyAST.xml
>
>
> Restrictions are pushed into a restricted VTI if you wrap it in a view.
> However, projections are not. I will attach a script showing this problem.
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