Berkeley DB
version 5.3.28

com.sleepycat.db
Class LockMode

java.lang.Object
  extended by com.sleepycat.db.LockMode

public final class LockMode
extends Object

Locking modes for database operations. Locking modes are required parameters for operations that retrieve data or modify the database.


Field Summary
static LockMode DEFAULT
          Acquire read locks for read operations and write locks for write operations.
static LockMode DEGREE_2
          Deprecated. This has been replaced by READ_COMMITTED to conform to ANSI database isolation terminology.
static LockMode DIRTY_READ
          Deprecated. This has been replaced by READ_UNCOMMITTED to conform to ANSI database isolation terminology.
static LockMode IGNORE_LEASES
          Return the data item irrespective of the state of master leases.
static LockMode READ_COMMITTED
          Read committed isolation provides for cursor stability but not repeatable reads.
static LockMode READ_UNCOMMITTED
          Read modified but not yet committed data.
static LockMode RMW
          Acquire write locks instead of read locks when doing the retrieval.
 
Method Summary
 String toString()
          
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

DEFAULT

public static final LockMode DEFAULT
Acquire read locks for read operations and write locks for write operations.


READ_UNCOMMITTED

public static final LockMode READ_UNCOMMITTED
Read modified but not yet committed data.


READ_COMMITTED

public static final LockMode READ_COMMITTED
Read committed isolation provides for cursor stability but not repeatable reads. Data items which have been previously read by this transaction may be deleted or modified by other transactions before the cursor is closed or the transaction completes.

Note that this LockMode may only be passed to Database get methods, not to Cursor methods. To configure a cursor for Read committed isolation, use CursorConfig.setReadCommitted(boolean).


RMW

public static final LockMode RMW
Acquire write locks instead of read locks when doing the retrieval. Setting this flag can eliminate deadlock during a read-modify-write cycle by acquiring the write lock during the read part of the cycle so that another thread of control acquiring a read lock for the same item, in its own read-modify-write cycle, will not result in deadlock.


DIRTY_READ

public static final LockMode DIRTY_READ
Deprecated. This has been replaced by READ_UNCOMMITTED to conform to ANSI database isolation terminology.
Read modified but not yet committed data.


DEGREE_2

public static final LockMode DEGREE_2
Deprecated. This has been replaced by READ_COMMITTED to conform to ANSI database isolation terminology.
Read committed isolation provides for cursor stability but not repeatable reads. Data items which have been previously read by this transaction may be deleted or modified by other transactions before the cursor is closed or the transaction completes.

Note that this LockMode may only be passed to Database get methods, not to Cursor methods. To configure a cursor for Read committed isolation, use CursorConfig.setReadCommitted(boolean).


IGNORE_LEASES

public static final LockMode IGNORE_LEASES
Return the data item irrespective of the state of master leases. The item will be returned under all conditions: if master leases are not configured, if the request is made to a client, if the request is made to a master with a valid lease, or if the request is made to a master without a valid lease.

Method Detail

toString

public String toString()

Overrides:
toString in class Object

Berkeley DB
version 5.3.28

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