Package org.eclipse.persistence.history

Class HistoryPolicy

  • All Implemented Interfaces:
    Serializable, Cloneable
    public class HistoryPolicy
extends Object
implements Cloneable, Serializable
    Purpose:Expresses how historical data is saved on the data store.

    This information is used to both maintain a history of all objects modified through TopLink and to enable point in time querying.

    If Oracle 9R2 or later Flashback is used this policy is not required, as the preservation of history is automatic.

    Descriptors, ManyToManyMappings, DirectCollectionMappings, and DirectMapMappings only can have a history policy, as only they have associated database tables.

    Since:
    10
    Author:
    Stephen McRitchie
    See Also:
    Serialized Form

    • Constructor Detail

      • HistoryPolicy

        public HistoryPolicy()

    • Method Detail

      • additionalHistoryExpression

        public Expression additionalHistoryExpression​(Expression context,
                                              Expression base)
        INTERNAL: Add any temporal querying conditions to this object expression.

      • additionalHistoryExpression

        public Expression additionalHistoryExpression​(Expression context,
                                              Expression base,
                                              Integer tableIndex)
        INTERNAL: Add any temporal querying conditions to this object expression.
        Parameters:
        tableIndex - not null indicates that only expression for a single table should be returned.

      • clone

        public Object clone()
        PUBLIC: Performs a sufficiently deep clone. Use to quickly setup standard policies on multiple descriptors.
        Overrides:
        clone in class Object

      • getCurrentTime

        public Object getCurrentTime​(AbstractSession session)
        PUBLIC: Whenever a historical record is logically deleted (updated) or inserted, the end and start fields respectively will be set to this value.

      • getMinimumTimeIncrement

        public long getMinimumTimeIncrement​(AbstractSession session)
        INTERNAL: Return a minimal time increment supported by the platform.

      • getDescriptor

        public ClassDescriptor getDescriptor()
        PUBLIC: Return the descriptor of the policy.

      • getHistoricalTables

        public final List<DatabaseTable> getHistoricalTables()
        INTERNAL:

      • getHistoryTableNames

        public List<String> getHistoryTableNames()
        PUBLIC:

      • getStart

        protected DatabaseField getStart​(int i)
        INTERNAL:

      • getStartFieldName

        public String getStartFieldName()
        PUBLIC: Answers the name of the start field. Assumes that multiple tables for a descriptor have the same field names.

      • getEndFieldName

        public String getEndFieldName()
        PUBLIC:

      • setDescriptor

        public void setDescriptor​(ClassDescriptor descriptor)
        PUBLIC:

      • initialize

        public void initialize​(AbstractSession session)
        INTERNAL: Initialize a HistoryPolicy.

      • addHistoryTableName

        public void addHistoryTableName​(String name)
        PUBLIC: Use to specify the names of the mirroring historical tables.

        Assumes that the order in which tables are added with descriptor.addTableName() matches the order in which mirroring historical tables are added with descriptor.addHistoryTableName().

      • addHistoryTableName

        public void addHistoryTableName​(String sourceTableName,
                                String historyTableName)
        PUBLIC: Use to specify the names of the mirroring historical tables.

        Explicitly states that sourceTableName is mirrored by history table historyTableName. The order in which tables are added with descriptor.addTableName() should still match the order in which mirroring historical tables are added with descriptor.addMirroringHistoryTableName().

      • setHistoricalTables

        public void setHistoricalTables​(List<DatabaseTable> historicalTables)
        INTERNAL:

      • setMapping

        public void setMapping​(DatabaseMapping mapping)
        INTERNAL:

      • setStartFields

        protected void setStartFields​(List<DatabaseField> startFields)
        INTERNAL:

      • addStartFieldName

        public void addStartFieldName​(String startFieldName)
        PUBLIC: Sets the name of the start field.

        By default all tables belonging to a descriptor have the same primary key field names, and so the same start field names also.

        However, if startFieldName is qualified, i.e. of the form "EMPLOYEE_HIST.EMP_START", then this call will only set the start field name for a single historical table.

      • setStartFieldType

        public void setStartFieldType​(Class type)
        ADVANCED: Sets the type of all start fields. Not required to be set as the default of Timestamp is assumed.

      • setEndFields

        protected void setEndFields​(List<DatabaseField> endFields)
        INTERNAL:

      • setShouldHandleWrites

        public void setShouldHandleWrites​(boolean value)
        Sets if TopLink is responsible for writing history.

        If history is maintained via low level database triggers or application logic a policy is still needed for point in time querying.

        If Oracle flashback is used no HistoryPolicy is needed.

        Setting this to false lets you use History for many other applications. For instance a table that tracks available flights or hotel deals may benefit from a HistoryPolicy just to simplify temporal querying.

        If all hotel discounts have a start and end date, you could query on all discounts available at a certain date.

      • shouldHandleWrites

        public boolean shouldHandleWrites()
        Answers if TopLink is responsible for writing history.

        If history is maintained via low level database triggers or application logic a policy is still usefull for point in time querying.

        If Oracle flashback is used no HistoryPolicy is needed.

        Returns:
        true by default
        See Also:
        setShouldHandleWrites(boolean)

      • setShouldUseDatabaseTime

        public void setShouldUseDatabaseTime​(boolean value)
        Sets if the Timestamp used in maintainaing history should be the current time according to the database.
        Parameters:
        value - if false uses localTime (default) instead

      • shouldUseLocalTime

        public boolean shouldUseLocalTime()
        Answers if the Timestamp used in maintaining history should be System.currentTimeMillis();
        Returns:
        true by default
        See Also:
        shouldUseDatabaseTime(), useLocalTime()

      • shouldUseDatabaseTime

        public boolean shouldUseDatabaseTime()
        Answers if the Timestamp used in maintaining history should be the current time according to the database.
        Returns:
        false by default
        See Also:
        shouldUseLocalTime(), useDatabaseTime()

      • useDatabaseTime

        public void useDatabaseTime()
        Answers if the Timestamp used in maintaining history should be the current time according to the database.
        See Also:
        useLocalTime(), shouldUseDatabaseTime()

      • verifyTableQualifiers

        protected void verifyTableQualifiers​(DatasourcePlatform platform)
        INTERNAL: Check that the qualifiers on the historical tables are properly set.

        A similar method exists on ClassDescriptor.

      • checkWastedVersioning

        protected boolean checkWastedVersioning​(AbstractRecord modifyRow,
                                        DatabaseTable table)
        INTERNAL: Checks for the case where an object has multiple tables but only some are part of a minimal update.

      • postDelete

        public void postDelete​(ModifyQuery deleteQuery)
        INTERNAL:

      • logicalInsert

        public void logicalInsert​(ObjectLevelModifyQuery writeQuery,
                          boolean isUpdate)
        INTERNAL: Perform a logical insert into the historical schema, creating a new version of an object.

        Called by postInsert() and also postUpdate() (which first does a logicalDelete of the previous version).

      • mappingLogicalInsert

        public void mappingLogicalInsert​(DataModifyQuery originalQuery,
                                 AbstractRecord arguments,
                                 AbstractSession session)
        INTERNAL: Performs a logical insert into the historical schema. Direct collections and many to many mappings are maintained through the session events.

      • logicalDelete

        public void logicalDelete​(ModifyQuery writeQuery,
                          boolean isUpdate)
        INTERNAL: Performs a logical delete (update) on the historical schema.

      • logicalDelete

        public void logicalDelete​(ModifyQuery writeQuery,
                          boolean isUpdate,
                          boolean isShallow)
        INTERNAL: Performs a logical delete (update) on the historical schema.

      • mappingLogicalDelete

        public void mappingLogicalDelete​(ModifyQuery originalQuery,
                                 AbstractRecord arguments,
                                 AbstractSession session)
        INTERNAL: Performs a logical delete (update) on the historical schema. Direct collections and many to many mappings are maintained through the session events.