Package org.eclipse.persistence.history

Class HistoryPolicy

java.lang.Object
org.eclipse.persistence.history.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.

See Also:
Author:
Stephen McRitchie

  • Field Details

    • descriptor

      protected ClassDescriptor descriptor

    • mapping

      protected DatabaseMapping mapping

    • historicalTables

      protected List<org.eclipse.persistence.internal.helper.DatabaseTable> historicalTables

    • startFields

      protected List<org.eclipse.persistence.internal.helper.DatabaseField> startFields

    • endFields

      protected List<org.eclipse.persistence.internal.helper.DatabaseField> endFields

    • shouldHandleWrites

      protected boolean shouldHandleWrites

    • usesLocalTime

      protected boolean usesLocalTime

  • Constructor Details

    • HistoryPolicy

      public HistoryPolicy()

  • Method Details

    • 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(org.eclipse.persistence.internal.sessions.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(org.eclipse.persistence.internal.sessions.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<org.eclipse.persistence.internal.helper.DatabaseTable> getHistoricalTables()
      INTERNAL:

    • getHistoryTableNames

      public List<String> getHistoryTableNames()
      PUBLIC:

    • getMapping

      public DatabaseMapping getMapping()
      PUBLIC:

    • getStart

      protected org.eclipse.persistence.internal.helper.DatabaseField getStart()
      INTERNAL:

    • getStart

      protected org.eclipse.persistence.internal.helper.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.

    • getStartFields

      public List<org.eclipse.persistence.internal.helper.DatabaseField> getStartFields()
      INTERNAL:

    • getEnd

      protected org.eclipse.persistence.internal.helper.DatabaseField getEnd()
      INTERNAL:

    • getEnd

      protected org.eclipse.persistence.internal.helper.DatabaseField getEnd(int i)
      INTERNAL:

    • getEndFieldName

      public String getEndFieldName()
      PUBLIC:

    • getEndFields

      public List<org.eclipse.persistence.internal.helper.DatabaseField> getEndFields()
      INTERNAL:

    • setDescriptor

      public void setDescriptor(ClassDescriptor descriptor)
      PUBLIC:

    • initialize

      public void initialize(org.eclipse.persistence.internal.sessions.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<org.eclipse.persistence.internal.helper.DatabaseTable> historicalTables)
      INTERNAL:

    • setMapping

      public void setMapping(DatabaseMapping mapping)
      INTERNAL:

    • setStartFields

      protected void setStartFields(List<org.eclipse.persistence.internal.helper.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<org.eclipse.persistence.internal.helper.DatabaseField> endFields)
      INTERNAL:

    • addEndFieldName

      public void addEndFieldName(String endFieldName)
      PUBLIC:
      See Also:

    • setEndFieldType

      public void setEndFieldType(String fieldName, Class type)
      ADVANCED:
      See Also:

    • 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:

    • 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

      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:

    • useLocalTime

      public void useLocalTime()
      Answers if the Timestamp used in maintaining history should be System.currentTimeMillis();
      See Also:

    • useDatabaseTime

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

    • verifyTableQualifiers

      protected void verifyTableQualifiers(org.eclipse.persistence.internal.databaseaccess.DatasourcePlatform platform)
      INTERNAL: Check that the qualifiers on the historical tables are properly set.

      A similar method exists on ClassDescriptor.

    • checkWastedVersioning

      protected boolean checkWastedVersioning(org.eclipse.persistence.internal.sessions.AbstractRecord modifyRow, org.eclipse.persistence.internal.helper.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:

    • postUpdate

      public void postUpdate(ObjectLevelModifyQuery writeQuery)
      INTERNAL:

    • postUpdate

      public void postUpdate(ObjectLevelModifyQuery writeQuery, boolean isShallow)
      INTERNAL:

    • postInsert

      public void postInsert(ObjectLevelModifyQuery writeQuery)
      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, org.eclipse.persistence.internal.sessions.AbstractRecord arguments, org.eclipse.persistence.internal.sessions.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, org.eclipse.persistence.internal.sessions.AbstractRecord arguments, org.eclipse.persistence.internal.sessions.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.