[jira] Commented: (JDO-448) Add an xml element to specify the fetch plan to use for a query

["Craig Russell (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JDO-448?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12536367 ] 

Craig Russell commented on JDO-448:
-----------------------------------

There are a couple of ways to handle this issue. 

1. Add element fetch-group*, and attributes max-fetch-depth, fetch-size to element query. These are used to set the FetchPlan in the stored query.

<query name="BySalary" max-fetch-depth="3" fetch-size="17">
  <fetch-group name="default"/>
  <fetch-group name="images"/>
SELECT THIS from Employee WHERE salary == :salary
</query>

2. Add a new fetch-plan element that contains fetch-group* and attributes name, max-fetch-depth, fetch-size. Add attribute fetch-plan to element query.

<fetch-plan name="EmployeeImages" max-fetch-depth="3" fetch-size="17">
  <fetch-group name="default"/>
  <fetch-group name="images"/>
</fetch-plan>

<query name="BySalary" fetch-plan="EmployeeImages">
SELECT THIS from Employee WHERE salary == :salary
</query>

3. Add a new fetch-plan element that contains fetch-group* and attributes max-fetch-depth, fetch-size. Add element fetch-plan to element query.

<query name="BySalary">
<fetch-plan name="EmployeeImages" max-fetch-depth="3" fetch-size="17">
  <fetch-group name="default"/>
  <fetch-group name="images"/>
</fetch-plan>
SELECT THIS from Employee WHERE salary == :salary
</query>

I like the idea of named fetch plans because the same fetch plan could then be used in multiple queries. Also, I think there is value in being able to specify declaratively what a fetch plan is, without having to use an API to declare it. We could use this in other places in the spec. 

So I'm leaning toward option 2. 

> Add an xml element to specify the fetch plan to use for a query
> ---------------------------------------------------------------
>
>                 Key: JDO-448
>                 URL: https://issues.apache.org/jira/browse/JDO-448
>             Project: JDO
>          Issue Type: New Feature
>          Components: api2, api2-legacy, specification
>    Affects Versions: JDO 2 final
>            Reporter: Michelle Caisse
>            Assignee: Craig Russell
>             Fix For: JDO 2 maintenance release 1
>
>
> In Chapter 18, add an xml element to specify the fetch plan to use for a query.

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