Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.diag.LockTable

Modifier and Type	Field and Description
public static final int	ALL return all locks and latches
private static final ResultColumnDescriptor[]	columnInfo
private Hashtable<K, V>	currentRow
private final int	flag
private boolean	initialized
public static final int	LATCH return only latches
private Enumeration<E>	lockTable
private static final ResultSetMetaData	metadata
private TableNameInfo	tabInfo
public static final int	TABLE_AND_ROWLOCK return only table and row locks
private TransactionController	tc
private boolean	wasNull

Access	Constructor and Description
public	LockTable() The normal way of instantiating a LockTable, equivalent to LockTable(org.apache.derby.diag.LockTable->TABLE_AND_ROWLOCK).
public	LockTable(int flag) This call is intrusive and should only be used under the supervision of technical support.

Modifier and Type	Method and Description
public void	close() Implements java.sql.ResultSet.close. Releases this `ResultSet` object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.
private Hashtable<String, Object>	dumpLock(Latch lock) Convert the lock information into a hashtable.
public double	getEstimatedCostPerInstantiation(VTIEnvironment The state variable for optimizing the Table Function. vtiEnvironment) Implements org.apache.derby.vti.VTICosting.getEstimatedCostPerInstantiation. Get the estimated cost for a single instantiation of a Table Function.
public double	getEstimatedRowCount(VTIEnvironment The state variable for optimizing the Table Function. vtiEnvironment) Implements org.apache.derby.vti.VTICosting.getEstimatedRowCount. Get the estimated row count for a single scan of a Table Function.
public ResultSetMetaData	getMetaData() Overrides org.apache.derby.vti.VTITemplate.getMetaData. Implements java.sql.ResultSet.getMetaData. Retrieves the number, types and properties of this `ResultSet` object's columns.
public String	getString(int the first column is 1, the second is 2, ... columnNumber) Overrides org.apache.derby.vti.VTITemplate.getString. Implements java.sql.ResultSet.getString. All columns in TransactionTable VTI are of String type.
public boolean	next() Implements java.sql.ResultSet.next. Moves the cursor forward one row from its current position.
public boolean	Returns: false supportsMultipleInstantiations(VTIEnvironment The state variable for optimizing the Table Function. vtiEnvironment) Implements org.apache.derby.vti.VTICosting.supportsMultipleInstantiations. Find out if the ResultSet of the Table Function can be instantiated multiple times.
public boolean	wasNull() Overrides org.apache.derby.vti.VTITemplate.wasNull. Implements java.sql.ResultSet.wasNull. Reports whether the last column read had a value of SQL `NULL`.

ALL	back to summary
public static final int ALL return all locks and latches

columnInfo	back to summary
private static final ResultColumnDescriptor[] columnInfo

currentRow	back to summary
private Hashtable<K, V> currentRow

flag	back to summary
private final int flag

initialized	back to summary
private boolean initialized

LATCH	back to summary
public static final int LATCH return only latches

lockTable	back to summary
private Enumeration<E> lockTable

tabInfo	back to summary
private TableNameInfo tabInfo

TABLE_AND_ROWLOCK	back to summary
public static final int TABLE_AND_ROWLOCK return only table and row locks

tc	back to summary
private TransactionController tc

wasNull	back to summary
private boolean wasNull

LockTable	back to summary
public LockTable() The normal way of instantiating a LockTable, equivalent to LockTable(org.apache.derby.diag.LockTable->TABLE_AND_ROWLOCK). Only shows row and table lock and not latches. Latches are generally held for very short duration and are not of interest to Derby users. Only under abnormal circumstances will one be interested in looking at latches.

LockTable	back to summary
public LockTable(int flag) This call is intrusive and should only be used under the supervision of technical support. Create an instance of the lock table which has transient latches as well as locks.

Method Detail

close back to summary

close	back to summary
public void close() Implements java.sql.ResultSet.close. Doc from java.sql.ResultSet.close. Releases this `ResultSet` object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed. The closing of a `ResultSet` object does not close the `Blob`, `Clob` or `NClob` objects created by the `ResultSet`. `Blob`, `Clob` or `NClob` objects remain valid for at least the duration of the transaction in which they are created, unless their `free` method is invoked. When a `ResultSet` is closed, any `ResultSetMetaData` instances that were created by calling the `getMetaData` method remain accessible. Note A `ResultSet` object is automatically closed by the `Statement` object that generated it when that `Statement` object is closed, re-executed, or is used to retrieve the next result from a sequence of multiple results. Calling the method `close` on a `ResultSet` object that is already closed is a no-op. See Also `java.sql.ResultSet#close`

public void close()

Releases this ResultSet object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.

The closing of a ResultSet object does not close the Blob, Clob or NClob objects created by the ResultSet. Blob, Clob or NClob objects remain valid for at least the duration of the transaction in which they are created, unless their free method is invoked.

When a ResultSet is closed, any ResultSetMetaData instances that were created by calling the getMetaData method remain accessible.

Note

A ResultSet object is automatically closed by the Statement object that generated it when that Statement object is closed, re-executed, or is used to retrieve the next result from a sequence of multiple results.

Calling the method close on a ResultSet object that is already closed is a no-op.

See Also: java.sql.ResultSet#close

dumpLock	back to summary
private Hashtable<String, Object> dumpLock(Latch lock) throws StandardException Convert the lock information into a hashtable.

getEstimatedCostPerInstantiation back to summary

getEstimatedCostPerInstantiation	back to summary
public double getEstimatedCostPerInstantiation(VTIEnvironment vtiEnvironment) Implements org.apache.derby.vti.VTICosting.getEstimatedCostPerInstantiation. Doc from org.apache.derby.vti.VTICosting.getEstimatedCostPerInstantiation. Get the estimated cost for a single instantiation of a Table Function. Parameters vtiEnvironment:VTIEnvironment The state variable for optimizing the Table Function. Returns:double The estimated cost for a single instantiation of the Table Function. See Also `VTICosting#getEstimatedCostPerInstantiation`

public double getEstimatedCostPerInstantiation(VTIEnvironment vtiEnvironment)

Implements org.apache.derby.vti.VTICosting.getEstimatedCostPerInstantiation.

Doc from org.apache.derby.vti.VTICosting.getEstimatedCostPerInstantiation.

Get the estimated cost for a single instantiation of a Table Function.

Parameters

vtiEnvironment:VTIEnvironment: The state variable for optimizing the Table Function.

Returns:double

The estimated cost for a single instantiation of the Table Function.

getEstimatedRowCount back to summary

getEstimatedRowCount	back to summary
public double getEstimatedRowCount(VTIEnvironment vtiEnvironment) Implements org.apache.derby.vti.VTICosting.getEstimatedRowCount. Doc from org.apache.derby.vti.VTICosting.getEstimatedRowCount. Get the estimated row count for a single scan of a Table Function. Parameters vtiEnvironment:VTIEnvironment The state variable for optimizing the Table Function. Returns:double The estimated row count for a single scan of the Table Function. See Also `VTICosting#getEstimatedRowCount`

public double getEstimatedRowCount(VTIEnvironment vtiEnvironment)

Implements org.apache.derby.vti.VTICosting.getEstimatedRowCount.

Doc from org.apache.derby.vti.VTICosting.getEstimatedRowCount.

Get the estimated row count for a single scan of a Table Function.

Parameters

vtiEnvironment:VTIEnvironment: The state variable for optimizing the Table Function.

Returns:double

The estimated row count for a single scan of the Table Function.

See Also

VTICosting#getEstimatedRowCount

getMetaData back to summary

public ResultSetMetaData getMetaData()

Overrides org.apache.derby.vti.VTITemplate.getMetaData.

Implements java.sql.ResultSet.getMetaData.

Doc from java.sql.ResultSet.getMetaData.

Retrieves the number, types and properties of this ResultSet object's columns.

Returns:ResultSetMetaData: the description of this ResultSet object's columns
See Also: java.sql.ResultSet#getMetaData

getString back to summary

getString	back to summary
public String getString(int columnNumber) Overrides org.apache.derby.vti.VTITemplate.getString. Implements java.sql.ResultSet.getString. All columns in TransactionTable VTI are of String type. Parameters columnNumber:int Doc from java.sql.ResultSet.getString. the first column is 1, the second is 2, ... Returns:String Doc from java.sql.ResultSet.getString. the column value; if the value is SQL `NULL`, the value returned is `null` See Also `java.sql.ResultSet#getString`

public String getString(int columnNumber)

Overrides org.apache.derby.vti.VTITemplate.getString.

Implements java.sql.ResultSet.getString.

All columns in TransactionTable VTI are of String type.

Parameters

columnNumber:int

Doc from java.sql.ResultSet.getString.

the first column is 1, the second is 2, ...

Returns:String

Doc from java.sql.ResultSet.getString.

the column value; if the value is SQL NULL, the value returned is null

See Also

java.sql.ResultSet#getString

next back to summary

next	back to summary
public boolean next() throws SQLException Implements java.sql.ResultSet.next. Doc from java.sql.ResultSet.next. Moves the cursor forward one row from its current position. A `ResultSet` cursor is initially positioned before the first row; the first call to the method `next` makes the first row the current row; the second call makes the second row the current row, and so on. When a call to the `next` method returns `false`, the cursor is positioned after the last row. Any invocation of a `ResultSet` method which requires a current row will result in a `SQLException` being thrown. If the result set type is `TYPE_FORWARD_ONLY`, it is vendor specified whether their JDBC driver implementation will return `false` or throw an `SQLException` on a subsequent call to `next`. If an input stream is open for the current row, a call to the method `next` will implicitly close it. A `ResultSet` object's warning chain is cleared when a new row is read. Returns:boolean `true` if the new current row is valid; `false` if there are no more rows Exceptions SQLException: if no transaction context can be found, or other Derby internal errors are encountered. See Also `java.sql.ResultSet#next`

public boolean next() throws SQLException

Implements java.sql.ResultSet.next.

Doc from java.sql.ResultSet.next.

Moves the cursor forward one row from its current position. A ResultSet cursor is initially positioned before the first row; the first call to the method next makes the first row the current row; the second call makes the second row the current row, and so on.

When a call to the next method returns false, the cursor is positioned after the last row. Any invocation of a ResultSet method which requires a current row will result in a SQLException being thrown. If the result set type is TYPE_FORWARD_ONLY, it is vendor specified whether their JDBC driver implementation will return false or throw an SQLException on a subsequent call to next.

If an input stream is open for the current row, a call to the method next will implicitly close it. A ResultSet object's warning chain is cleared when a new row is read.

Returns:boolean

true if the new current row is valid; false if there are no more rows

Exceptions

SQLException:: if no transaction context can be found, or other Derby internal errors are encountered.

See Also

java.sql.ResultSet#next

supportsMultipleInstantiations back to summary

supportsMultipleInstantiations	back to summary
public boolean supportsMultipleInstantiations(VTIEnvironment vtiEnvironment) Implements org.apache.derby.vti.VTICosting.supportsMultipleInstantiations. Doc from org.apache.derby.vti.VTICosting.supportsMultipleInstantiations. Find out if the ResultSet of the Table Function can be instantiated multiple times. Parameters vtiEnvironment:VTIEnvironment The state variable for optimizing the Table Function. Returns:boolean false See Also `VTICosting#supportsMultipleInstantiations`

public boolean supportsMultipleInstantiations(VTIEnvironment vtiEnvironment)

Implements org.apache.derby.vti.VTICosting.supportsMultipleInstantiations.

Doc from org.apache.derby.vti.VTICosting.supportsMultipleInstantiations.

Find out if the ResultSet of the Table Function can be instantiated multiple times.

Parameters

vtiEnvironment:VTIEnvironment: The state variable for optimizing the Table Function.

Returns:boolean

false

wasNull back to summary

wasNull	back to summary
public boolean wasNull() Overrides org.apache.derby.vti.VTITemplate.wasNull. Implements java.sql.ResultSet.wasNull. Doc from java.sql.ResultSet.wasNull. Reports whether the last column read had a value of SQL `NULL`. Note that you must first call one of the getter methods on a column to try to read its value and then call the method `wasNull` to see if the value read was SQL `NULL`. Returns:boolean `true` if the last column value read was SQL `NULL` and `false` otherwise See Also `java.sql.ResultSet#wasNull`

public boolean wasNull()

Overrides org.apache.derby.vti.VTITemplate.wasNull.

Implements java.sql.ResultSet.wasNull.

Doc from java.sql.ResultSet.wasNull.

Reports whether the last column read had a value of SQL NULL. Note that you must first call one of the getter methods on a column to try to read its value and then call the method wasNull to see if the value read was SQL NULL.

Returns:boolean: true if the last column value read was SQL NULL and false otherwise
See Also: java.sql.ResultSet#wasNull

public Class LockTable

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