Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.impl.sql.execute.AutoincrementCounter

AutoincrementCounter is a not so general counter for the specific purposes of autoincrement columns. It can be thought of as an in-memory autoincrement column. The counting or incrementing is done in fashion identical to the AUTOINCREMENTVALUE in SYSCOLUMNS.

To create a counter, the user must call the constructor with a start value, increment and optionally a final value. In addition the caller must specify the schema name, table name and column name uniquely identifying the counter.

When a counter is created it is in an invalid state-- to initialize it, the user must call either update or reset(false). The value of a counter can be changed by either calling reset or update.

Field Summary

Modifier and Type	Field and Description
private String	columnName
private int	columnPosition
private long	counter
private long	finalValue
private String	identity
private long	increment
private boolean	initialized
private String	schemaName
private Long	start
private String	tableName

Constructor Summary

Access	Constructor and Description
public	AutoincrementCounter(Long The start value of the counter; is a java object as it can also be null. start, long how much to increment the counter by. increment, long the finalvalue of the counter. used by reset finalValue, String s, String t, String c, int position) constructor

Method Summary

Modifier and Type	Method and Description
public void	flushToDisk(TransactionController TransactionController to use tc, DataDictionary DataDictionary to use. dd, UUID I might have the table name but I need more information tableUUID) flush a counter to disk; i.e write the current value of the counter into the row in SYSCOLUMNS.
public int	Returns: the position of the corresponding column in the table (1-based) getColumnPosition() get the column position in the table for which this counter has been created.
public Long	getCurrentValue() get the current value of the counter.
public String	getIdentity() return the identity of the counter.
public Long	Returns: the initial value of the counter getStartValue() get the start value
public static String	makeIdentity(String s, String t, String c) make a unique key for the counter.
public static String	makeIdentity(TableDescriptor td, ColumnDescriptor cd) make a unique key for the counter.
public void	reset(boolean if TRUE reset to beginning and mark it uninitialized. begin) reset to the counter to the beginning or the end.
public String	toString() Overrides java.lang.Object.toString. Returns a string representation of the object.
public long	update(long update the counter to this value. t) update the counter.
public long	update() update the counter to its next value.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll wait wait wait

Field Detail

columnName	back to summary
private String columnName

columnPosition	back to summary
private int columnPosition

counter	back to summary
private long counter

finalValue	back to summary
private long finalValue

identity	back to summary
private String identity

increment	back to summary
private long increment

initialized	back to summary
private boolean initialized

schemaName	back to summary
private String schemaName

start	back to summary
private Long start

tableName	back to summary
private String tableName

Constructor Detail

AutoincrementCounter	back to summary
public AutoincrementCounter(Long start, long increment, long finalValue, String s, String t, String c, int position) constructor Parameters start:Long The start value of the counter; is a java object as it can also be null. increment:long how much to increment the counter by. finalValue:long the finalvalue of the counter. used by reset

AutoincrementCounter

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public AutoincrementCounter(Long start, long increment, long finalValue, String s, String t, String c, int position)

constructor

Parameters

start:Long: The start value of the counter; is a java object as it can also be null.
increment:long: how much to increment the counter by.
finalValue:long: the finalvalue of the counter. used by reset

Method Detail

flushToDisk	back to summary
public void flushToDisk(TransactionController tc, DataDictionary dd, UUID tableUUID) throws StandardException flush a counter to disk; i.e write the current value of the counter into the row in SYSCOLUMNS. Parameters tc:TransactionController TransactionController to use dd:DataDictionary DataDictionary to use. tableUUID:UUID I might have the table name but I need more information Exceptions StandardException: standard Derby exception.

flushToDisk

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public void flushToDisk(TransactionController tc, DataDictionary dd, UUID tableUUID) throws StandardException

flush a counter to disk; i.e write the current value of the counter into the row in SYSCOLUMNS.

Parameters

tc:TransactionController: TransactionController to use
dd:DataDictionary: DataDictionary to use.
tableUUID:UUID: I might have the table name but I need more information

Exceptions

StandardException:: standard Derby exception.

getColumnPosition	back to summary
public int getColumnPosition() get the column position in the table for which this counter has been created. Returns:int the position of the corresponding column in the table (1-based)

getColumnPosition

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public int getColumnPosition()

get the column position in the table for which this counter has been created.

Returns:int: the position of the corresponding column in the table (1-based)

getCurrentValue	back to summary
public Long getCurrentValue() get the current value of the counter. An uninitialized counter means the current value is NULL.

getIdentity	back to summary
public String getIdentity() return the identity of the counter.

getStartValue	back to summary
public Long getStartValue() get the start value Returns:Long the initial value of the counter

getStartValue

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public Long getStartValue()

get the start value

Returns:Long: the initial value of the counter

makeIdentity	back to summary
public static String makeIdentity(String s, String t, String c) make a unique key for the counter.

makeIdentity	back to summary
public static String makeIdentity(TableDescriptor td, ColumnDescriptor cd) make a unique key for the counter.

reset	back to summary
public void reset(boolean begin) reset to the counter to the beginning or the end. Parameters begin:boolean if TRUE reset to beginning and mark it uninitialized.

reset

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public void reset(boolean begin)

reset to the counter to the beginning or the end.

Parameters

begin:boolean: if TRUE reset to beginning and mark it uninitialized.

toString back to summary

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Doc from java.lang.Object.toString. Returns a string representation of the object. Satisfying this method's contract implies a non-`null` result must be returned. Returns:String a string representation of the object

public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object. Satisfying this method's contract implies a non-null result must be returned.

Returns:String: a string representation of the object

update	back to summary
public long update(long t) update the counter. Parameters t:long update the counter to this value.

update

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public long update(long t)

update the counter.

Parameters

t:long: update the counter to this value.

update	back to summary
public long update() throws StandardException update the counter to its next value. Exceptions StandardException: if the counter has not yet been initialized and the Start value is NULL.

update

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public long update() throws StandardException

update the counter to its next value.

Exceptions

StandardException:: if the counter has not yet been initialized and the Start value is NULL.

public Class AutoincrementCounter

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail