Package org.datanucleus.store.rdbms.table

Class CollectionTable

java.lang.Object

org.datanucleus.store.rdbms.table.AbstractTable

org.datanucleus.store.rdbms.table.TableImpl

org.datanucleus.store.rdbms.table.JoinTable

org.datanucleus.store.rdbms.table.ElementContainerTable

org.datanucleus.store.rdbms.table.CollectionTable

All Implemented Interfaces:

Table, org.datanucleus.store.schema.table.Table

public class CollectionTable
extends ElementContainerTable

Representation of a join table for a Collection. A Collection covers a wide range of possibilities in terms of whether it allows duplicates or not, whether it allows nulls or not, whether it supports ordering via indexes, whether it supports ordering via a SELECT criteria, etc. Consequently the join table can vary depending on the required capabilities.

JoinTable Mappings

The join table consists of the following mappings :-

• ownerMapping linking back to the owning class with the Collection.
• elementMapping either being an FK link to the element table or being an embedded/serialised element stored wholly in this table.
• orderMapping which may be null, or otherwise stores an index for the elements. This is either to provide uniqueness or ordering in a List (and part of the PK).

Note that with an M-N relation there will be 2 instances of the CollectionTable - one represents the relation from owner to element, and the other for the relation from element to owner.

Field Summary

Fields inherited from class org.datanucleus.store.rdbms.table.ElementContainerTable

elementMapping, orderMapping, relationDiscriminatorMapping, relationDiscriminatorValue

Fields inherited from class org.datanucleus.store.rdbms.table.JoinTable

mmd, ownerMapping, ownerTable, ownerType

Fields inherited from class org.datanucleus.store.rdbms.table.AbstractTable

columns, columnsByIdentifier, dba, existsInDatastore, identifier, state, storeMgr, TABLE_STATE_INITIALIZED, TABLE_STATE_INITIALIZED_MODIFIED, TABLE_STATE_NEW, TABLE_STATE_PK_INITIALIZED, TABLE_STATE_VALIDATED

Constructor Summary

Constructors

Constructor	Description
CollectionTable(Table ownerTable, DatastoreIdentifier tableName, org.datanucleus.metadata.AbstractMemberMetaData mmd, RDBMSStoreManager storeMgr)	Constructor.

Method Summary

Modifier and Type	Method	Description
String	getElementType()	Accessor for the element type stored in this Collection/Set/List.
void	initialize(org.datanucleus.ClassLoaderResolver clr)	Method to initialise the table definition.
boolean	isEmbeddedElement()	Accessor for whether the element is embedded into this table.
boolean	isEmbeddedElementPC()	Accessor for whether the element is a persistable(embedded).
boolean	isSerialisedElement()	Accessor for whether the element is serialised into this table.
boolean	isSerialisedElementPC()	Accessor for whether the element is a persistable(serialised)
protected boolean	requiresPrimaryKey()	Convenience method for whether a PK is required for the join table.

Methods inherited from class org.datanucleus.store.rdbms.table.ElementContainerTable

applyUserPrimaryKeySpecification, getElementMapping, getExpectedCandidateKeys, getExpectedForeignKeys, getExpectedIndices, getForeignKeyToElement, getForeignKeyToOwner, getMemberMapping, getOrderMapping, getRelationDiscriminatorMapping, getRelationDiscriminatorValue

Methods inherited from class org.datanucleus.store.rdbms.table.JoinTable

getIdMapping, getOwnerMapping, getOwnerMemberMetaData, getOwnerTable, getPrimaryKey

Methods inherited from class org.datanucleus.store.rdbms.table.TableImpl

createConstraints, dropConstraints, getSQLAddCandidateKeyStatements, getSQLAddFKStatements, getSQLCreateIndexStatements, getSQLCreateStatements, getSQLDropStatements, initializeColumnInfoForPrimaryKeyColumns, initializeColumnInfoFromDatastore, logMapping, validate, validateColumns, validateConstraints, validatePrimaryKey

Methods inherited from class org.datanucleus.store.rdbms.table.AbstractTable

addColumn, addColumnInternal, allowDDLOutput, assertIsInitialized, assertIsInitializedModified, assertIsPKInitialized, assertIsPKUninitialized, assertIsUninitialized, assertIsValidated, create, drop, equals, executeDdlStatement, executeDdlStatementList, exists, getCatalogName, getClassMetaData, getColumn, getColumnForName, getColumnForPosition, getColumns, getDatastoreIdentifierFullyQualified, getDiscriminatorMetaData, getIdentifier, getMemberColumnMappingForEmbeddedMember, getMemberColumnMappingForMember, getMemberColumnMappings, getName, getNumberOfColumns, getSchemaName, getStoreManager, getSurrogateColumn, getSurrogateMapping, getVersionMetaData, hasColumn, hasColumnName, hashCode, isInitialized, isInitializedModified, isPKInitialized, isValidated, postInitialize, preInitialize, tableExistsInDatastore, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CollectionTable

public CollectionTable(Table ownerTable,
                       DatastoreIdentifier tableName,
                       org.datanucleus.metadata.AbstractMemberMetaData mmd,
                       RDBMSStoreManager storeMgr)

Constructor.

Parameters:

ownerTable - Table of the owner of this member

tableName - Identifier name of the table

mmd - MetaData for the member of the owner

storeMgr - The Store Manager managing these tables.

Method Detail

initialize

public void initialize(org.datanucleus.ClassLoaderResolver clr)

Method to initialise the table definition.

Specified by:

initialize in interface Table

Overrides:

initialize in class ElementContainerTable

Parameters:

clr - The ClassLoaderResolver

getElementType

public String getElementType()

Accessor for the element type stored in this Collection/Set/List.

Specified by:

getElementType in class ElementContainerTable

Returns:

Name of element type.

isSerialisedElement

public boolean isSerialisedElement()

Accessor for whether the element is serialised into this table. This can be a serialised persistable, or a serialised simple type

Returns:

Whether the element is serialised.

isEmbeddedElement

public boolean isEmbeddedElement()

Accessor for whether the element is embedded into this table. This can be an embedded persistable, or an embedded simple type

Returns:

Whether the element is embedded.

isSerialisedElementPC

public boolean isSerialisedElementPC()

Accessor for whether the element is a persistable(serialised)

Returns:

Whether the element is PC and is serialised

isEmbeddedElementPC

public boolean isEmbeddedElementPC()

Accessor for whether the element is a persistable(embedded). Currently this only defines a PC element as embedded if the MetaData has an <embedded> block. This may or may not be correct depending on how you interpret the JDO2 spec "embedded-element" flag.

Returns:

Whether the element is PC and is embedded

requiresPrimaryKey

protected boolean requiresPrimaryKey()

Convenience method for whether a PK is required for the join table. Extends JoinTable allowing for "ordered List" case which do not require a primary key (so we can have duplicates).

Overrides:

requiresPrimaryKey in class JoinTable

Returns:

Whether a PK is required