org.apache.derby.impl.sql.catalog
Class SequenceRange

java.lang.Object
  org.apache.derby.impl.sql.catalog.SequenceRange

All Implemented Interfaces:

SequencePreallocator

public class SequenceRange
extends java.lang.Object
implements SequencePreallocator

Default Derby logic for determining how many values to pre-allocate for an identity column or sequence.

Field Summary

private int	_rangeSize
private static int	DEFAULT_PREALLOCATION_COUNT Default number of values to pre-allocate.

Constructor Summary

SequenceRange()
0-arg constructore needed to satisfy the SequencePreallocator contract.

SequenceRange(int rangeSize)

Method Summary

int	nextRangeSize(java.lang.String schemaName, java.lang.String sequenceName) This method returns the size of the next pre-allocated range for the specified sequence.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PREALLOCATION_COUNT

private static final int DEFAULT_PREALLOCATION_COUNT

Default number of values to pre-allocate. Other databases use a preallocation size of 20 (see DERBY-4437). We boosted this to 100 in order to get better concurrency, after fixing correctness problems in pre-allocation (see DERBY-5493).

See Also:

Constant Field Values

_rangeSize

private int _rangeSize

Constructor Detail

SequenceRange

public SequenceRange()

0-arg constructore needed to satisfy the SequencePreallocator contract.

SequenceRange

public SequenceRange(int rangeSize)

Method Detail

nextRangeSize

public int nextRangeSize(java.lang.String schemaName,
                         java.lang.String sequenceName)

Description copied from interface: SequencePreallocator

This method returns the size of the next pre-allocated range for the specified sequence. Names are case-sensitive, as specified in CREATE SEQUENCE and CREATE TABLE statements.

Specified by:

nextRangeSize in interface SequencePreallocator

Parameters:

schemaName - Name of schema holding the sequence.

sequenceName - Specific name of the sequence.