Class SequenceRange
- java.lang.Object
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- org.apache.derby.impl.sql.catalog.SequenceRange
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- 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.
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Field Summary
Fields Modifier and Type Field Description private int
_rangeSize
private static int
DEFAULT_PREALLOCATION_COUNT
Default number of values to pre-allocate.
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Constructor Summary
Constructors Constructor Description SequenceRange()
0-arg constructore needed to satisfy the SequencePreallocator contract.SequenceRange(int rangeSize)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description 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.
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Field Detail
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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
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_rangeSize
private int _rangeSize
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Method Detail
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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 interfaceSequencePreallocator
- Parameters:
schemaName
- Name of schema holding the sequence.sequenceName
- Specific name of the sequence.
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