Examples of FetchGroup

javax.jdo.FetchGroup
FetchGroup represents a named fetch group for a specific class or interface. A fetch group instance identifies the name of the class or interface, the list of members (fields or properties) to be fetched when the fetch group is active, and the recursion depth for each member.
Fetch groups are updated using methods on this interface. An instance of a class implementing this interface can be obtained from {@link PersistenceManager#getFetchGroup} or{@link PersistenceManagerFactory#getFetchGroup}.
A FetchGroup can be unscoped or can be in one of two scopes (the {@link PersistenceManager} or the {@link PersistenceManagerFactory} scope). Unscoped FetchGroups do not affect any behavior. A FetchGroup in PersistenceManager scope hides the corresponding FetchGroup in the PersistenceManagerFactory scope.
- When a FetchGroup is obtained via {@link PersistenceManager#getFetchGroup}, it is immediately in scope of its PersistenceManager. Subsequent modifications of the FetchGroup immediately affect FetchPlans that contain the FetchGroup.
- When a FetchGroup is obtained via {@link PersistenceManagerFactory#getFetchGroup}, it is unscoped.
- When a FetchGroup is added to the set of active FetchGroups via {@link PersistenceManagerFactory#addFetchGroups}, it is put in scope of the PersistenceManagerFactory.
- When a FetchGroup is removed from the set of active FetchGroups via {@link PersistenceManagerFactory#removeFetchGroups}, {@link PersistenceManagerFactory#removeAllFetchGroups}, or replaced via {@link PersistenceManagerFactory#addFetchGroups}, it is unscoped.
@version 2.2 @since 2.2
oracle.toplink.essentials.queryframework.FetchGroup

Purpose: A fetch group is a performance enhancement that allows a group of attributes of an object to be loaded on demand, which means that the data for an attribute might not loaded from the underlying data source until an explicit access call for the attribute first occurs. It avoids the wasteful practice of loading up all data of the object?s attributes, in which the user is interested in only partial of them. A great deal of caution and careful system use case analysis should be use when using the fetch group feature, as the extra round-trip would well offset the gain from the deferred loading in many cases. TopLink fetch group support is twofold: the pre-defined fetch groups at the descriptor level; and dynamic (use case) fetch groups at the query level. TopLink fetch group support is only on CMP project. Every query can has at most one fetch group. There is an optional pre-defined default fetch group at the descriptor level. If set, and the query has no fetch group being set, the default fetch group would be used, unless query.setShouldUseDefaultFetchGroup(false) is also called. In the latter case, the full object will be fetched after the query execution. @see oracle.toplink.essentials.queryframework.FetchGroup @see oracle.toplink.essentials.queryframework.FetchGroupTracker @author King Wang @since TopLink 10.1.3.
org.apache.james.mailbox.MessageResult.FetchGroup
org.apache.james.mailbox.model.MessageResult.FetchGroup
org.apache.openjpa.meta.FetchGroup
Captures fetch group metadata.
org.datanucleus.FetchGroup
Group of fields for fetching, to be part of a FetchPlan. Defined at runtime, via the API.
org.eclipse.persistence.queries.FetchGroup
A FetchGroup is a performance enhancement that allows a group of attributes of an object to be loaded on demand, which means that the data for an attribute might not loaded from the underlying data source until an explicit access call for the attribute first occurs. It avoids loading all data of the object's attributes, in which the user is interested in only a subset of them. A great deal of caution and careful system use case analysis should be use when using the fetch group feature, as the extra round-trip would well offset the gain from the deferred loading in many cases.
FetchGroup usage is only possible when an entity class implements the {@link FetchGroupTracker} interface so that the FetchGroup can be stored inthe entity. The entity must also use the provided check methods to ensure the attributes are loaded prior to use. In general this support is enabled through weaving of the entity classes. If an entity class does not implement {@link FetchGroupTracker} no FetchGroup functionality will be supported andattempted use of a FetchGroup in a query will not result in the expected behavior.
FetchGroups are defined in 3 ways:
- A {@link FetchGroupManager#getDefaultFetchGroup()} is created and storedon the {@link FetchGroupManager} during metadata processing if any of thebasic ( {@link DirectToFieldMapping}) are configured to be loaded directly.
- A named FetchGroup can be defined and added to the {@link FetchGroupManager}. For JPA users this can be accomplished using annotation (@FetchGroup) or in an eclipselink-orm.xml. For JPA and native users named groups can be defined in code and added to the {@link FetchGroupManager#addFetchGroup(FetchGroup)}. Adding named groups in code is typically done in a {@link DescriptorCustomizer}and should be done before the session is initialized at login. To use a named FetchGroup on a query the native {@link ObjectLevelReadQuery#setFetchGroupName(String)} canbe used of for JPA users the {@link QueryHints#FETCH_GROUP_NAME} an be used.
- A dynamic FetchGroup can be created within the application and used on a query. For native API usage this is done using {@link ObjectLevelReadQuery#setFetchGroup(FetchGroup)} while JPA usersgenerally use the {@link QueryHints#FETCH_GROUP}.
When a query is executed only one FetchGroup will be used. The order of precedence is:
1. If a FetchGroup is specified on a query it will be used.
2. If no FetchGroup is specified but a FetchGroup name is specified and the FetchGroupManager has a group by this name it will be used.
3. If neither a FetchGroup nor a FetchGroup name is specified on the query an the FetchGroupManager has a default group then it will be used.
4. If none of these conditions are met then no FetchGroup will be used when executing a query.
  Note: This includes the execution of queries to populate lazy and eager relationships.
  Loading: A FetchGroup can optionally specify that it needs its included relationships loaded. This can be done using {@link #setShouldLoad(boolean)} and {@link #setShouldLoadAll(boolean)} aswell as the corresponding configurations in the @FetchGroup annotation and the element in the eclipselink-orm.xml. When this si configured the FetchGroup will also function as a {@link LoadGroup} causing all of itsspecified relationships to be populated prior to returning the results form the query execution. @see FetchGroupManager @see QueryHints#FETCH_GROUP @see LoadGroup @author King Wang, dclarke, ailitchev @since TopLink 10.1.3

Examples of org.apache.openjpa.meta.FetchGroup

3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247     /**      * Perform post-load actions if the given fetch group is a post-load group      * and is fully loaded.      */     private boolean postLoad(String fgName, FetchConfiguration fetch) {         FetchGroup fg = _meta.getFetchGroup(fgName);         if (fg == null || !fg.isPostLoad())             return false;         FieldMetaData[] fmds = _meta.getFields();         for (int i = 0; i < fmds.length; i++)             if (!_loaded.get(i) && fmds[i].isInFetchGroup(fgName))

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Examples of org.apache.openjpa.meta.FetchGroup

3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309     /**      * Perform post-load actions if the given fetch group is a post-load group      * and is fully loaded.      */     private boolean postLoad(String fgName, FetchConfiguration fetch) {         FetchGroup fg = _meta.getFetchGroup(fgName);         if (fg == null || !fg.isPostLoad())             return false;         FieldMetaData[] fmds = _meta.getFields();         for (int i = 0; i < fmds.length; i++)             if (!_loaded.get(i) && fmds[i].isInFetchGroup(fgName))

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Examples of org.apache.openjpa.meta.FetchGroup

3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232     /**      * Perform post-load actions if the given fetch group is a post-load group      * and is fully loaded.      */     private boolean postLoad(String fgName, FetchConfiguration fetch) {         FetchGroup fg = _meta.getFetchGroup(fgName);         if (fg == null || !fg.isPostLoad())             return false;         FieldMetaData[] fmds = _meta.getFields();         for (int i = 0; i < fmds.length; i++)             if (!_loaded.get(i) && fmds[i].isInFetchGroup(fgName))

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Examples of org.datanucleus.FetchGroup

2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309         JDOFetchGroup jdoGrp = (JDOFetchGroup)getPersistenceManagerFactory().getFetchGroup(cls, name);         if (jdoGrp != null)         {             // PMF returned us a group (maybe newly created) so put a copy in scope here             // We actually copy the internal group to the OM, and have our own JDOFetchGroup here             FetchGroup internalGrp = (jdoGrp).getInternalFetchGroup();             FetchGroup internalCopy = new FetchGroup(internalGrp);             jdoGrp = new JDOFetchGroup(internalCopy);             om.addInternalFetchGroup(internalCopy);             jdoFetchGroups.add(jdoGrp);             return jdoGrp;         }

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Examples of org.eclipse.persistence.queries.FetchGroup

774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789             super(QueryHints.FETCH_GROUP_ATTRIBUTE, "");         }             DatabaseQuery applyToDatabaseQuery(Object valueToApply, DatabaseQuery query, ClassLoader loader) {             if (query.isObjectLevelReadQuery()) {                 FetchGroup fetchGroup = ((ObjectLevelReadQuery)query).getFetchGroup();                 if (fetchGroup == null) {                     fetchGroup = new FetchGroup();                     ((ObjectLevelReadQuery)query).setFetchGroup(fetchGroup);                 }                 fetchGroup.addAttribute((String)valueToApply);             } else {                 throw new IllegalArgumentException(ExceptionLocalization.buildMessage("ejb30-wrong-type-for-query-hint",new Object[]{getQueryId(query), name, getPrintValue(valueToApply)}));             }             return query;         }

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Examples of org.eclipse.persistence.queries.FetchGroup

127 128 129 130 131 132 133 134 135 136 137      * Return true if the object is partially fetched and cached.      * It applies to the query with fetch group.      */     public boolean isPartialObject(Object domainObject) {         if (domainObject != null) {             FetchGroup fetchGroupInCache = ((FetchGroupTracker)domainObject)._persistence_getFetchGroup();             //if the fetch group reference is not null, it means the object is partial.             return (fetchGroupInCache != null);         }         return false;

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Examples of org.eclipse.persistence.queries.FetchGroup

140 141 142 143 144 145 146 147     /**      * INTERNAL:      * Return if the cached object data is sufficiently valid against a fetch group      */     public boolean isObjectValidForFetchGroup(Object object, FetchGroup fetchGroup) {         FetchGroup groupInObject = ((FetchGroupTracker)object)._persistence_getFetchGroup();         return (groupInObject == null) || groupInObject.isSupersetOf(fetchGroup);     }

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Examples of org.eclipse.persistence.queries.FetchGroup

151 152 153 154 155 156 157 158 159 160 161 162 163 164      * Return true if the cached object data should be written in clone.      * It is used in Fetch Group case when filling in the clone from the cached object.      */     public boolean shouldWriteInto(Object cachedObject, Object clone) {         if (isPartialObject(clone)) {             FetchGroup fetchGroupInSrc = ((FetchGroupTracker)cachedObject)._persistence_getFetchGroup();             FetchGroup fetchGroupInTarg = ((FetchGroupTracker)clone)._persistence_getFetchGroup();             //if the target fetch group is not null (i.e. fully fetched object) or if partially fetched, it's not a superset of that of the source,             //or if refresh is required, should always write (either refresh or revert) data from the cache to the clones.             return (!((fetchGroupInTarg == null) || fetchGroupInTarg.isSupersetOf(fetchGroupInSrc)) || ((FetchGroupTracker)cachedObject)._persistence_shouldRefreshFetchGroup());         }         return false;     }

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Examples of org.eclipse.persistence.queries.FetchGroup

166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182     /**      * INTERNAL:      * Write data of the partially fetched object into the working and backup clones      */     public void writePartialIntoClones(Object partialObject, Object workingClone, UnitOfWorkImpl uow) {         FetchGroup fetchGroupInClone = ((FetchGroupTracker)workingClone)._persistence_getFetchGroup();         FetchGroup fetchGroupInObject = ((FetchGroupTracker)partialObject)._persistence_getFetchGroup();         Object backupClone = uow.getBackupClone(workingClone, descriptor);         // Update fetch group in clone as the union of two,         // do this first to avoid fetching during method access.         FetchGroup union = unionFetchGroups(fetchGroupInObject, fetchGroupInClone);         // Finally, update clone's fetch group reference.         setObjectFetchGroup(workingClone, union, uow);         if (workingClone != backupClone) {             setObjectFetchGroup(backupClone, union, uow);         }

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Examples of org.eclipse.persistence.queries.FetchGroup

280 281 282 283 284 285 286 287 288 289         //otherwise, union two fetch groups         StringBuffer unionGroupName = new StringBuffer(first.getName());         unionGroupName.append("_");         unionGroupName.append(second.getName());         FetchGroup unionFetchGroup = new FetchGroup(unionGroupName.toString());         unionFetchGroup.addAttributes(first.getAttributes());         unionFetchGroup.addAttributes(second.getAttributes());         return unionFetchGroup;     }

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