Package com.sleepycat.db

Class Sequence

java.lang.Object
com.sleepycat.db.Sequence
public class Sequence extends Object
A Sequence handle is used to manipulate a sequence record in a database. Sequence handles are opened using the Database.openSequence method.

  • Method Details

    • close

      public void close() throws DatabaseException
      Close a sequence. Any unused cached values are lost.

      The sequence handle may not be used again after this method has been called, regardless of the method's success or failure.

      Throws:
      DatabaseException - if a failure occurs.

    • get

      public long get(Transaction txn, int delta) throws DatabaseException
      Return the next available element in the sequence and changes the sequence value by delta. The value of delta must be greater than zero. If there are enough cached values in the sequence handle then they will be returned. Otherwise the next value will be fetched from the database and incremented (decremented) by enough to cover the delta and the next batch of cached values.

      The txn handle must be null if the sequence handle was opened with a non-zero cache size.

      For maximum concurrency, a non-zero cache size should be specified prior to opening the sequence handle, the txn handle should be null, and SequenceConfig.setAutoCommitNoSync should be called to disable log flushes.

      Parameters:
      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.

      delta - the amount by which to increment or decrement the sequence

      Returns:
      the next available element in the sequence
      Throws:
      DatabaseException

    • getDatabase

      public Database getDatabase() throws DatabaseException
      Return the Database handle associated with this sequence.

      Returns:
      The Database handle associated with this sequence.
      Throws:
      DatabaseException

    • getKey

      public DatabaseEntry getKey() throws DatabaseException
      Return the DatabaseEntry used to open this sequence.

      Returns:
      The DatabaseEntry used to open this sequence.
      Throws:
      DatabaseException

    • getStats

      public SequenceStats getStats(StatsConfig config) throws DatabaseException
      Return statistical information about the sequence.

      In the presence of multiple threads or processes accessing an active sequence, the information returned by this method may be out-of-date.

      The getStats method cannot be transaction-protected. For this reason, it should be called in a thread of control that has no open cursors or active transactions.

      Parameters:
      config - The statistics returned; if null, default statistics are returned.

      Returns:
      Sequence statistics.
      Throws:
      DatabaseException