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From "Howard M. Lewis Ship (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (TAP5-902) GridDataSource does not allow performing less than 2 queries if returning results
Date Mon, 30 Jun 2014 23:25:24 GMT

    [ https://issues.apache.org/jira/browse/TAP5-902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14048295#comment-14048295
] 

Howard M. Lewis Ship commented on TAP5-902:
-------------------------------------------

The issue is that prepare() needs to know the number of available rows in order to calculate
values for startIndex and endIndex.  The two queries issue is unavoidable if we want to handle
very large result sets.  

I'm sure a smart implementation could, for small result sets, do a single query, then provide
a subset of the results.

> GridDataSource does not allow performing less than 2 queries if returning results
> ---------------------------------------------------------------------------------
>
>                 Key: TAP5-902
>                 URL: https://issues.apache.org/jira/browse/TAP5-902
>             Project: Tapestry 5
>          Issue Type: Improvement
>          Components: tapestry-core
>    Affects Versions: 5.1.0.5
>            Reporter: Dan Adams
>            Assignee: Howard M. Lewis Ship
>
> By having getAvailableRows() and prepare() separate, any implementation is forced to
perform 2 queries. Many systems allow getting the results of a query and the total count in
one query so that you don't have to perform 2 queries. Getting around this requires some pretty
gross hacks (unless you just don't use grid at all which is unfortunate).



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