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Berkeley DB Java Edition version ${release.version} |
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java.lang.Objectcom.sleepycat.je.Database
public class Database
A database handle.
Database attributes are specified in the DatabaseConfig
class. Database handles are
free-threaded and may be used concurrently by multiple threads.
To open an existing database with default attributes:
Environment env = new Environment(home, null); Database myDatabase = env.openDatabase(null, "mydatabase", null);
To create a transactional database that supports duplicates:
DatabaseConfig dbConfig = new DatabaseConfig(); dbConfig.setTransactional(true); dbConfig.setAllowCreate(true); dbConfig.setSortedDuplicates(true); Database newlyCreateDb = env.openDatabase(txn, "mydatabase", dbConfig);
Constructor Summary | |
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protected |
Database(Environment env)
Creates a database but does not open or fully initialize it. |
Method Summary | |
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void |
close()
Discards the database handle. |
long |
count()
Counts the key/data pairs in the database. |
OperationStatus |
delete(Transaction txn,
DatabaseEntry key)
Removes key/data pairs from the database. |
OperationStatus |
get(Transaction txn,
DatabaseEntry key,
DatabaseEntry data,
LockMode lockMode)
Retrieves the key/data pair with the given key. |
DatabaseConfig |
getConfig()
Returns this Database object's configuration. |
String |
getDatabaseName()
Returns the database name. |
Environment |
getEnvironment()
Returns the Environment handle for
the database environment underlying the Database . |
OperationStatus |
getSearchBoth(Transaction txn,
DatabaseEntry key,
DatabaseEntry data,
LockMode lockMode)
Retrieves the key/data pair with the given key and data value, that is, both the key and data items must match. |
List<SecondaryDatabase> |
getSecondaryDatabases()
Returns a list of all SecondaryDatabase objects associated with a primary database. |
DatabaseStats |
getStats(StatsConfig config)
Returns database statistics. |
JoinCursor |
join(Cursor[] cursors,
JoinConfig config)
Creates a specialized join cursor for use in performing equality or natural joins on secondary indices. |
Cursor |
openCursor(Transaction txn,
CursorConfig cursorConfig)
Returns a cursor into the database. |
Sequence |
openSequence(Transaction txn,
DatabaseEntry key,
SequenceConfig config)
Opens a sequence in the database. |
void |
preload(long maxBytes)
Deprecated. As of JE 2.0.83, replaced by preload(PreloadConfig) . |
void |
preload(long maxBytes,
long maxMillisecs)
Deprecated. As of JE 2.0.101, replaced by preload(PreloadConfig) . |
PreloadStats |
preload(PreloadConfig config)
Preloads the cache. |
OperationStatus |
put(Transaction txn,
DatabaseEntry key,
DatabaseEntry data)
Stores the key/data pair into the database. |
OperationStatus |
putNoDupData(Transaction txn,
DatabaseEntry key,
DatabaseEntry data)
Stores the key/data pair into the database if it does not already appear in the database. |
OperationStatus |
putNoOverwrite(Transaction txn,
DatabaseEntry key,
DatabaseEntry data)
Stores the key/data pair into the database if the key does not already appear in the database. |
void |
removeSequence(Transaction txn,
DatabaseEntry key)
Removes the sequence from the database. |
void |
sync()
Flushes any cached information for this database to disk; only applicable for deferred-write databases. |
DatabaseStats |
verify(VerifyConfig config)
Verifies the integrity of the database. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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protected Database(Environment env)
env
- Method Detail |
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public void close() throws DatabaseException
When closing the last open handle for a deferred-write database, any
cached database information is flushed to disk as if sync()
were
called.
The database handle should not be closed while any other handle that
refers to it is not yet closed; for example, database handles should not
be closed while cursor handles into the database remain open, or
transactions that include operations on the database have not yet been
committed or aborted. Specifically, this includes Cursor
and Transaction
handles.
When multiple threads are using the Database
handle concurrently, only a single thread may call this
method.
The database handle may not be accessed again after this method is called, regardless of the method's success or failure.
When called on a database that is the primary database for a secondary index, the primary database should be closed only after all secondary indices which reference it have been closed.
DatabaseException
- if a failure occurs.DatabaseConfig.setDeferredWrite
public void sync() throws DatabaseException
Note that deferred-write databases are automatically flushed to disk
when the close()
method is called.
DatabaseException
- if a failure occurs.DatabaseConfig.setDeferredWrite
public Sequence openSequence(Transaction txn, DatabaseEntry key, SequenceConfig config) throws DatabaseException
txn
- For a transactional database, an explicit transaction may
be specified, or null may be specified to use auto-commit. For a
non-transactional database, null must be specified.key
- The key DatabaseEntry
of the sequence.config
- The sequence attributes. If null, default
attributes are used.
DatabaseException
- if a failure occurs.public void removeSequence(Transaction txn, DatabaseEntry key) throws DatabaseException
txn
- For a transactional database, an explicit transaction may be
specified, or null may be specified to use auto-commit. For a
non-transactional database, null must be specified.key
- The key DatabaseEntry
of the sequence.
DatabaseException
public Cursor openCursor(Transaction txn, CursorConfig cursorConfig) throws DatabaseException
txn
- To use a cursor for writing to a transactional database, an
explicit transaction must be specified. For read-only access to a
transactional database, the transaction may be null. For a
non-transactional database, the transaction must be null.
To transaction-protect cursor operations, cursors must be opened and closed within the context of a transaction, and the txn parameter specifies the transaction context in which the cursor will be used.
cursorConfig
- The cursor attributes. If null, default
attributes are used.
DatabaseException
- if a failure occurs.public OperationStatus delete(Transaction txn, DatabaseEntry key) throws DatabaseException
The key/data pair associated with the specified key is discarded from the database. In the presence of duplicate key values, all records associated with the designated key will be discarded.
The key/data pair is also deleted from any associated secondary databases.
txn
- For a transactional database, an explicit transaction may
be specified, or null may be specified to use auto-commit. For a
non-transactional database, null must be specified.key
- the key DatabaseEntry
operated on.
OperationStatus.NOTFOUND
if
the specified key is not found in the database; otherwise the method
will return OperationStatus.SUCCESS
.
DeadlockException
- if the operation was selected to resolve a
deadlock.
DatabaseException
- if a failure occurs.public OperationStatus get(Transaction txn, DatabaseEntry key, DatabaseEntry data, LockMode lockMode) throws DatabaseException
Cursor
operations.
txn
- For a transactional database, an explicit transaction may be
specified to transaction-protect the operation, or null may be specified
to perform the operation without transaction protection. For a
non-transactional database, null must be specified.key
- the key used as input. It must be initialized with a
non-null byte array by the caller.data
- the data returned as output. Its byte array does not need
to be initialized by the caller.lockMode
- the locking attributes; if null, default attributes are
used.
OperationStatus.NOTFOUND
if no matching key/data pair is found;
otherwise, OperationStatus.SUCCESS
.
DeadlockException
- if the operation was selected to resolve a
deadlock.
IllegalArgumentException
- if an invalid parameter was specified.
DatabaseException
- if a failure occurs.public OperationStatus getSearchBoth(Transaction txn, DatabaseEntry key, DatabaseEntry data, LockMode lockMode) throws DatabaseException
txn
- For a transactional database, an explicit transaction may be
specified to transaction-protect the operation, or null may be specified
to perform the operation without transaction protection. For a
non-transactional database, null must be specified.key
- the keyused as input. It must be initialized with a non-null
byte array by the caller.data
- the dataused as input. It must be initialized with a
non-null byte array by the caller.lockMode
- the locking attributes; if null, default attributes are
used.
OperationStatus.NOTFOUND
if no matching key/data pair is found;
otherwise, OperationStatus.SUCCESS
.
DeadlockException
- if the operation was selected to resolve a
deadlock.
IllegalArgumentException
- if an invalid parameter was specified.
DatabaseException
- if a failure occurs.public OperationStatus put(Transaction txn, DatabaseEntry key, DatabaseEntry data) throws DatabaseException
If the key already appears in the database and duplicates are not configured, the data associated with the key will be replaced. If the key already appears in the database and sorted duplicates are configured, the new data value is inserted at the correct sorted location.
txn
- For a transactional database, an explicit transaction may be
specified, or null may be specified to use auto-commit. For a
non-transactional database, null must be specified.key
- the key DatabaseEntry
operated on.data
- the data DatabaseEntry
stored.
OperationStatus.SUCCESS
if the operation succeeds.
DeadlockException
- if the operation was selected to resolve a
deadlock.
DatabaseException
- if a failure occurs.public OperationStatus putNoOverwrite(Transaction txn, DatabaseEntry key, DatabaseEntry data) throws DatabaseException
This method will return OpeationStatus.KEYEXIST
if
the key already exists in the database, even if the database supports
duplicates.
txn
- For a transactional database, an explicit transaction may be
specified, or null may be specified to use auto-commit. For a
non-transactional database, null must be specified.key
- the key DatabaseEntry
operated on.data
- the data DatabaseEntry
stored.
OperationStatus.KEYEXIST
if the key already appears in the database,
else OperationStatus.SUCCESS
DeadlockException
- if the operation was selected to resolve a
deadlock.
DatabaseException
- if any other failure occurs.public OperationStatus putNoDupData(Transaction txn, DatabaseEntry key, DatabaseEntry data) throws DatabaseException
This method may only be called if the underlying database has been configured to support sorted duplicates.
txn
- For a transactional database, an explicit transaction may be
specified, or null may be specified to use auto-commit. For a
non-transactional database, null must be specified.key
- the key DatabaseEntry
operated on.data
- the data DatabaseEntry
stored.
OperationStatus.KEYEXIST
.
DeadlockException
- if the operation was selected to resolve a
deadlock.
DatabaseException
- if a failure occurs.public JoinCursor join(Cursor[] cursors, JoinConfig config) throws DatabaseException
Each cursor in the cursors
array must have been
initialized to refer to the key on which the underlying database should
be joined. Typically, this initialization is done by calling Cursor.getSearchKey
.
Once the cursors have been passed to this method, they should not be accessed or modified until the newly created join cursor has been closed, or else inconsistent results may be returned. However, the position of the cursors will not be changed by this method or by the methods of the join cursor.
cursors
- an array of cursors associated with this primary
database.config
- The join attributes. If null, default attributes are
used.
DatabaseException
- if a failure occurs. @see JoinCursorpublic void preload(long maxBytes) throws DatabaseException
preload(PreloadConfig)
.
maxBytes
- The maximum number of bytes to load. If maxBytes is 0,
je.evictor.maxMemory is used.
DatabaseException
- if a failure occurs.public void preload(long maxBytes, long maxMillisecs) throws DatabaseException
preload(PreloadConfig)
.
maxBytes
- The maximum number of bytes to load. If maxBytes is 0,
je.evictor.maxMemory is used.maxMillisecs
- The maximum time in milliseconds to use when
preloading. Preloading stops once this limit has been reached. If
maxMillisecs is 0, preloading can go on indefinitely or until maxBytes
(if non-0) is reached.
DatabaseException
- if a failure occurs.public PreloadStats preload(PreloadConfig config) throws DatabaseException
config
- The PreloadConfig object that specifies the parameters
of the preload.
DatabaseException
- if a failure occurs.public long count() throws DatabaseException
A count of the key/data pairs in the database is returned without adding to the cache. The count may not be accurate in the face of concurrent update operations in the database.
DatabaseException
public DatabaseStats getStats(StatsConfig config) throws DatabaseException
If this method has not been configured to avoid expensive operations
(using the StatsConfig.setFast
method), it will access some of or all the pages in
the database, incurring a severe performance penalty as well as possibly
flushing the underlying cache.
In the presence of multiple threads or processes accessing an active database, the information returned by this method may be out-of-date.
config
- The statistics returned; if null, default statistics are
returned.
DeadlockException
- if the operation was selected to resolve a
deadlock.
DatabaseException
- if a failure occurs.public DatabaseStats verify(VerifyConfig config) throws DatabaseException
Verification is an expensive operation that should normally only be used for troubleshooting and debugging.
config
- Configures the verify operation; if null, the default
operation is performed.
IllegalArgumentException
- if an invalid parameter was specified.
DatabaseException
- if a failure occurs.public String getDatabaseName() throws DatabaseException
This method may be called at any time during the life of the application.
DatabaseException
public DatabaseConfig getConfig() throws DatabaseException
This may differ from the configuration used to open this object if the database existed previously.
DatabaseException
- if a failure occurs.public Environment getEnvironment() throws DatabaseException
Environment
handle for
the database environment underlying the Database
.
This method may be called at any time during the life of the application.
Environment
handle
for the database environment underlying the Database
.
DatabaseException
- if a failure occurs.public List<SecondaryDatabase> getSecondaryDatabases() throws DatabaseException
SecondaryDatabase
objects associated with a primary database.
If no secondaries are associated or this is itself a secondary database, an empty list is returned.
SecondaryDatabase
objects associated with a primary database.
DatabaseException
|
Berkeley DB Java Edition version ${release.version} |
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