com.sleepycat.bdb
Class DataView

java.lang.Object
  |
  +--com.sleepycat.bdb.DataView

All Implemented Interfaces:

Cloneable

public final class DataView

extends Object

implements Cloneable

(internal) Represents a Berkeley DB database and adds support for indices, bindings and key ranges.

NOTE: This classes is internal and may be changed incompatibly or deleted in the future. It is public only so it may be used by subpackages.

This class defines a view and takes care of reading and updating indices, calling bindings, constraining access to a key range, etc.

Constructor Summary

DataView(DataStore store, DataIndex index, DataBinding keyBinding, DataBinding valueBinding, EntityBinding entityBinding, boolean writeAllowed)
Creates a view for a given store/index and bindings.

Method Summary

int	addValue(DataThang primaryKeyThang, Object value, int flags) Adds a duplicate value for a specified key.
int	append(Object value, Object[] retPrimaryKey, Object[] retValue) Appends a value and returns the new key.
boolean	areDuplicatesAllowed() Returns whether duplicates are allowed for the index or store.
boolean	areDuplicatesOrdered() Returns whether duplicates are ordered for the index or store.
boolean	areKeysRenumbered() Returns whether keys (record numbers) are renumbered for the index or store.
DataView	autoCommitView(boolean enable) Returns a new view with a specified autoCommit setting.
boolean	canDeriveKeyFromValue() Returns whether data keys can be derived from the value/entity binding of this view, which determines whether a value/entity object alone is sufficient for operations that require keys.
void	clear(Collection oldValues) Deletes all records in the current range, optionally returning the values for the deleted records.
int	consume(int flags, Object[] retPrimaryKey, Object[] retValue) Performs a database 'get and consume' operation.
DataView	dirtyReadView(boolean enable) Returns a new view with a specified dirtyRead setting.
int	get(Object key, Object value, int flags, boolean lockForWrite, Object[] retValue) Performs a general database 'get' operation.
CurrentTransaction	getCurrentTxn() Returns the current transaction for the view or null if the environment is non-transactional.
DataDb	getDb() Returns the database for the index, if one is used, or store, if no index is used.
DbEnv	getEnv() Returns the environment for the store and index.
DataIndex	getIndex() Returns the index, as specified to the constructor.
DataBinding	getKeyBinding() Returns the key binding that is used.
DataThang	getSingleKeyThang() Returns the key thang for a single key range, or null if a single key range is not used.
DataStore	getStore() Returns the store, as specified to the constructor.
DataBinding	getValueBinding() Returns the value binding that is used.
EntityBinding	getValueEntityBinding() Returns the entity binding that is used.
boolean	isAutoCommit() Returns whether auto-commit is set for this view or for the transactional environment of the store and index.
boolean	isDirtyReadAllowed() Returns whether DIRTY_READ was specified for both the Store and Index.
boolean	isDirtyReadEnabled() Returns whether DIRTY_READ will be used for all read operations.
boolean	isEmpty() Returns whether no records are present in the view.
boolean	isOrdered() Returns whether keys are ordered for the index or store.
boolean	isTransactional() Returns whether the store and index are transactional.
boolean	isWriteAllowed() Returns whether write operations are allowed.
DataCursor	join(DataCursor[] indexCursors, boolean presorted) Returns a cursor for this view that reads only records having the index key values at the specified cursors.
DataCursor	join(DataView[] indexViews, Object[] indexKeys, boolean presorted) Returns a cursor for this view that reads only records having the specified index key values.
DataView	keySetView() Return a new key-set view derived from this view by setting the entity and value binding to null.
int	put(Object primaryKey, Object value, int flags, Object[] oldValue) Performs a database 'put' operation, optionally returning the old value.
DataView	subView(Object beginKey, boolean beginInclusive, Object endKey, boolean endInclusive, DataBinding keyBinding) Return a new value-set view for key range, optionally changing the key binding.
DataView	valueSetView() Return a new value-set view derived from this view by setting the key binding to null.
DataView	valueSetView(Object singleKey) Return a new value-set view for single key range.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DataView

public DataView(DataStore store,
                DataIndex index,
                DataBinding keyBinding,
                DataBinding valueBinding,
                EntityBinding entityBinding,
                boolean writeAllowed)
         throws IllegalArgumentException

Creates a view for a given store/index and bindings. The key range of the view will be open.

Parameters:

store - is the store or is ignored if the index parameter is given.

index - is the index or null if no index is used.

keyBinding - is the key binding or null if keys will not be used.

valueBinding - is the value binding or null if an entityBinding is given or if values will not be used.

entityBinding - is the entity binding or null if an valueBinding is given or if values will not be used.

writeAllowed - is whether writing through this view is allowed.

Throws:

IllegalArgumentException - if formats are not consistently defined or a parameter is invalid.

Method Detail

keySetView

public DataView keySetView()

Return a new key-set view derived from this view by setting the entity and value binding to null.

Returns:

the derived view.

valueSetView

public DataView valueSetView()

Return a new value-set view derived from this view by setting the key binding to null.

Returns:

the derived view.

valueSetView

public DataView valueSetView(Object singleKey)
                      throws DbException,
                             IOException,
                             KeyRangeException

Return a new value-set view for single key range.

Parameters:

singleKey - the single key value.

Returns:

the derived view.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

KeyRangeException - if the specified range is not within the current range.

subView

public DataView subView(Object beginKey,
                        boolean beginInclusive,
                        Object endKey,
                        boolean endInclusive,
                        DataBinding keyBinding)
                 throws DbException,
                        IOException,
                        KeyRangeException

Return a new value-set view for key range, optionally changing the key binding.

Parameters:

beginKey - the lower bound.

beginInclusive - whether the lower bound is inclusive.

endKey - the upper bound.

endInclusive - whether the upper bound is inclusive.

keyBinding - a key binding to use, or null to retain the base view's key binding.

Returns:

the derived view.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

KeyRangeException - if the specified range is not within the current range.

dirtyReadView

public DataView dirtyReadView(boolean enable)

Returns a new view with a specified dirtyRead setting.

Parameters:

enable - whether to enable or disable dirty-read.

Returns:

the derived view.

autoCommitView

public DataView autoCommitView(boolean enable)

Returns a new view with a specified autoCommit setting. Note that auto-commit is not implemented by the view, the view only holds the auto-commit property.

Parameters:

enable - whether to enable or disable auto-commit.

Returns:

the derived view.

getCurrentTxn

public CurrentTransaction getCurrentTxn()

Returns the current transaction for the view or null if the environment is non-transactional.

Returns:

the current transaction.

getSingleKeyThang

public DataThang getSingleKeyThang()

Returns the key thang for a single key range, or null if a single key range is not used.

Returns:

the key thang or null.

getDb

public DataDb getDb()

Returns the database for the index, if one is used, or store, if no index is used.

Returns:

the database of the index or, if none, the store.

getEnv

public final DbEnv getEnv()

Returns the environment for the store and index.

Returns:

the environment.

isAutoCommit

public final boolean isAutoCommit()

Returns whether auto-commit is set for this view or for the transactional environment of the store and index. Note that auto-commit is not implemented by the view, the view only holds the auto-commit property.

Returns:

the auto-commit setting.

getStore

public final DataStore getStore()

Returns the store, as specified to the constructor.

Returns:

the store.

getIndex

public final DataIndex getIndex()

Returns the index, as specified to the constructor.

Returns:

the index or null.

getKeyBinding

public final DataBinding getKeyBinding()

Returns the key binding that is used.

Returns:

the key binding or null.

getValueBinding

public final DataBinding getValueBinding()

Returns the value binding that is used.

Returns:

the value binding or null.

getValueEntityBinding

public final EntityBinding getValueEntityBinding()

Returns the entity binding that is used.

Returns:

the entity binding or null.

areDuplicatesAllowed

public final boolean areDuplicatesAllowed()

Returns whether duplicates are allowed for the index or store.

Returns:

whether duplicates are allowed.

areDuplicatesOrdered

public final boolean areDuplicatesOrdered()

Returns whether duplicates are ordered for the index or store.

Returns:

whether duplicates are ordered.

areKeysRenumbered

public final boolean areKeysRenumbered()

Returns whether keys (record numbers) are renumbered for the index or store.

Returns:

whether keys are renumbered.

isOrdered

public final boolean isOrdered()

Returns whether keys are ordered for the index or store.

Returns:

whether keys are ordered.

isWriteAllowed

public final boolean isWriteAllowed()

Returns whether write operations are allowed.

Returns:

whether write operations are allowed.

isDirtyReadAllowed

public final boolean isDirtyReadAllowed()

Returns whether DIRTY_READ was specified for both the Store and Index.

Returns:

whether dirty-read is allowed.

isDirtyReadEnabled

public final boolean isDirtyReadEnabled()

Returns whether DIRTY_READ will be used for all read operations.

Returns:

whether dirty-read is enabled.

isTransactional

public final boolean isTransactional()

Returns whether the store and index are transactional.

Returns:

whether the store and index are transactional.

isEmpty

public boolean isEmpty()
                throws DbException,
                       IOException

Returns whether no records are present in the view.

Returns:

whether the view is empty.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

get

public int get(Object key,
               Object value,
               int flags,
               boolean lockForWrite,
               Object[] retValue)
        throws DbException,
               IOException

Performs a general database 'get' operation.

Parameters:

key - used to find the value

value - used to find the value

flags - all flags except DB_SET and DB_GET_BOTH are legal, Db.get(DbTxn,Dbt,Dbt,int).

lockForWrite - if true locks the cursor during the get.

retValue - used to store the result of the query

Returns:

0 if mathing values are found, Db.DB_NOTFOUND if not.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

consume

public int consume(int flags,
                   Object[] retPrimaryKey,
                   Object[] retValue)
            throws DbException,
                   IOException

Performs a database 'get and consume' operation.

Parameters:

flags - must be CONSUME or CONSUME_WAIT.

retPrimaryKey - used to store the resulting key.

retValue - used to store the resulting value.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

put

public int put(Object primaryKey,
               Object value,
               int flags,
               Object[] oldValue)
        throws DbException,
               IOException

Performs a database 'put' operation, optionally returning the old value.

Parameters:

primaryKey - key of new record.

value - value of new record.

flags - must be 0, NODUPDATA or NOOVERWRITE.

oldValue - used to store the old value, or null if none should be returned.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

addValue

public int addValue(DataThang primaryKeyThang,
                    Object value,
                    int flags)
             throws DbException,
                    IOException

Adds a duplicate value for a specified key.

Parameters:

primaryKeyThang - key of new record.

value - value of new record.

flags - must be 0 or NODUPDATA or KEYFIRST or KEYLAST.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

append

public int append(Object value,
                  Object[] retPrimaryKey,
                  Object[] retValue)
           throws DbException,
                  IOException

Appends a value and returns the new key. If a key assigner is used it assigns the key, otherwise a QUEUE or RECNO database is required.

Parameters:

value - is the value to append.

retPrimaryKey - used to store the assigned key.

retValue - used to store the resulting entity, or null if none should be returned.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

clear

public void clear(Collection oldValues)
           throws DbException,
                  IOException

Deletes all records in the current range, optionally returning the values for the deleted records.

Parameters:

oldValues - is used to store the values that are cleared, or null if the old values should not be returned.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

join

public DataCursor join(DataView[] indexViews,
                       Object[] indexKeys,
                       boolean presorted)
                throws DbException,
                       IOException

Returns a cursor for this view that reads only records having the specified index key values.

Parameters:

indexViews - are the views to be joined.

indexKeys - are the keys to join on for each view.

presorted - is whether the given views are presorted or should be sorted by number of values per key.

Returns:

the join cursor.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

join

public DataCursor join(DataCursor[] indexCursors,
                       boolean presorted)
                throws DbException,
                       IOException

Returns a cursor for this view that reads only records having the index key values at the specified cursors.

Parameters:

presorted - is whether the given cursors are presorted or should be sorted by number of values per key.

Returns:

the join cursor.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

canDeriveKeyFromValue

public boolean canDeriveKeyFromValue()

Returns whether data keys can be derived from the value/entity binding of this view, which determines whether a value/entity object alone is sufficient for operations that require keys.

Returns:

whether data keys can be derived.