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| − | {{EclipseLink_TLJPA
| + | #REDIRECT [[EclipseLink/UserGuide/JPA/2.4/toc]] |
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| − | |category=JPA
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| − | |release=2.4.x
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| − | |title= }}
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| − | <span class="metaname"> </span>
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| − | {| class="simple oac_no_warn" width="100%"
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| − | [http://www.google.com/cse/home?cx=016171230611334810008:y5kxq4rqd8s&hl=en Search]
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| − | [[EclipseLink/UserGuide/JPA/toc| Contents]] | + | |
| − | |}
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| − | |}
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| − | ----
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| − | {| width="150"
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| − | [[EclipseLink/UserGuide/JPA/a_array|<- Previous]]
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| − | [[EclipseLink/UserGuide/JPA/a_cache|Next ->]]
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| − | <span id="CHDCCIDA"></span>
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| − | ----
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| − | ==@BatchFetch==
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| − | Use <code>@BatchFetch</code> to read objects related to a relationship mapping (such as one-to-one, one-to-many, many-to-one, many-to-many, and element collection) to be read in a single query.
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| − | <span id="sthref27"></span>
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| − | ''' '''
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| − | ===Annotation Elements===
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| − | [[#CHDJBJBC|Table 2-1]] describes this annotation's elements.
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| − | <span id="sthref28"></span><span id="CHDJBJBC"></span>
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| − | '''''Table 2-1 @BatchFetch Annotation Elements'''''
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| − | {| class="HRuleFormalWide" dir="ltr" title="@BatchFetch Annotation Elements" summary="This table describes the list of attributes for this annotation." width="100%" border="1" frame="hsides" rules="rows" cellpadding="3" frame="hsides" rules="rows"
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| − | |- align="left" valign="top"
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| − | ! id="r1c1-t2" align="left" valign="bottom" | '''Annotation Element'''
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| − | ! id="r1c2-t2" align="left" valign="bottom" | '''Description'''
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| − | ! id="r1c3-t2" align="left" valign="bottom" | '''Default'''
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| − | |- align="left" valign="top"
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| − | | id="r2c1-t2" headers="r1c1-t2" align="left" |
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| − | size
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| − | | headers="r2c1-t2 r1c2-t2" align="left" |
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| − | Default size of the batch fetch, used only when <code>BatchFetchType</code>=<code>IN</code> to definite number of keys in each <code>IN</code> clause
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| − | | headers="r2c1-t2 r1c3-t2" align="left" |
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| − | <code>256</code> or the query's <code>pageSize</code> (for cursor queries)
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| − | |- align="left" valign="top"
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| − | | id="r3c1-t2" headers="r1c1-t2" align="left" |
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| − | BatchFetchType
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| − | | headers="r3c1-t2 r1c2-t2" align="left" |
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| − | (optional) The type of batch fetch to use:
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| − | * JOIN
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| − | * EXISTS
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| − | * IN
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| − | | headers="r3c1-t2 r1c3-t2" align="left" |
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| − | JOIN
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| − | |}
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| − | <br />
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| − | <span id="sthref29"></span>
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| − | ''' '''
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| − | ===Usage===
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| − | Batch fetching allows for the optimal loading of a tree. Setting the <code>@BatchFetch</code> annotation on a ''child'' relationship of a tree structure causes EclipseLink to use a ''single'' SQL statement for each level.
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| − | <span id="sthref30"></span>
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| − | ''' '''
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| − | ===Examples===
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| − | Para.
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| − | <span id="sthref31"></span>
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| − | '''''Example 2-1 Using JOIN BatchFetch Type'''''
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| − | <span id="sthref32"></span>
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| − | '''''Example 2-2 Using EXISTS BatchFetch Type'''''
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| − | <span id="sthref33"></span>
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| − | '''''Example 2-3 Using IN BatchFetch Type'''''
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| − | <span id="sthref34"></span>
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| − | ''' '''
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| − | ===See Also===
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| − | For more information, see:
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| − | * [[EclipseLink/UserGuide/JPA/a_joinfetch|"@JoinFetch"]]
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| − | ----
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| − | {| class="simple oac_no_warn" width="100%"
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| − | {| width="150"
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| − | [[EclipseLink/UserGuide/JPA/a_array|<- Previous]]
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| − | [[EclipseLink/UserGuide/JPA/a_cache|Next ->]]
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| − | |}
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| − | | width="34%" align="center" |
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| − | [[Image:Eclipselink-logo.gif|150px|EclispeLink]]<br />[http://wiki.eclipse.org/EclipseLink EclipseLink Home]<br />
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| − | {| class="simple oac_no_warn" width="225"
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| − | [http://www.google.com/cse/home?cx=016171230611334810008:y5kxq4rqd8s&hl=en Search]
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| − | | align="center" valign="top" |
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| − | [[EclipseLink/UserGuide/JPA/toc| Contents]]
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| − | |}
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| − | |}
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