org.apache.derby.diag
Class TransactionTable

java.lang.Object
  org.apache.derby.vti.VTITemplateBase
      org.apache.derby.vti.VTITemplate
          org.apache.derby.diag.TransactionTable

All Implemented Interfaces:

java.sql.ResultSet, java.sql.Wrapper, VTICosting

public class TransactionTable
extends VTITemplate
implements VTICosting

TransactionTable is a virtual table that shows all transactions currently in the database. This virtual table can be invoked by calling it directly

 select * from SYSCS_DIAG.TRANSACTION_TABLE 

The TransactionTable virtual table takes a snap shot of the transaction table while the system is in flux, so it is possible that some transactions may be in transition state while the snap shot is taken. We choose to do this rather then impose extraneous timing restrictions so that the use of this tool will not alter the normal timing and flow of execution in the application.

The TransactionTable virtual table has the following columns:

• XID varchar(15) - not nullable. The transaction id, this can be joined with the LockTable virtual table's XID.
• GLOBAL_XID varchar(140) - nullable. The global transaction id, only set if this transaction is a participant in a distributed transaction.
• USERNAME varchar(128) - nullable. The user name, or APP by default. May appear null if the transaction is started by Derby.
• TYPE varchar(30) - not nullable. UserTransaction or an internal transaction spawned by Derby.
• STATUS varchar(8) - not nullable. IDLE or ACTIVE. A transaction is IDLE only when it is first created or right after it commits. Any transaction that holds or has held any resource in the database is ACTIVE. Accessing the TransactionTable virtual table without using the class alias will not activate the transaction.
• FIRST_INSTANT varchar(20) - nullable. If null, this is a read only transaction. If not null, this is the first log record instant written by the transaction.
• SQL_TEXT VARCHAR(32672) - nullable. if null, this transaction is currently not being executed in the database. If not null, this is the SQL statement currently being executed in the database.

Field Summary

private static ResultColumnDescriptor[]	columnInfo
(package private) int	currentRow
(package private) boolean	initialized
private static java.sql.ResultSetMetaData	metadata
private TransactionInfo[]	transactionTable
private boolean	wasNull

Fields inherited from interface org.apache.derby.vti.VTICosting

defaultEstimatedCost, defaultEstimatedRowCount

Fields inherited from interface java.sql.ResultSet

CLOSE_CURSORS_AT_COMMIT, CONCUR_READ_ONLY, CONCUR_UPDATABLE, FETCH_FORWARD, FETCH_REVERSE, FETCH_UNKNOWN, HOLD_CURSORS_OVER_COMMIT, TYPE_FORWARD_ONLY, TYPE_SCROLL_INSENSITIVE, TYPE_SCROLL_SENSITIVE

Constructor Summary

TransactionTable()

Method Summary

void	close()
double	getEstimatedCostPerInstantiation(VTIEnvironment vtiEnvironment) Get the estimated cost for a single instantiation of a Table Function.
double	getEstimatedRowCount(VTIEnvironment vtiEnvironment) Get the estimated row count for a single scan of a Table Function.
java.sql.ResultSetMetaData	getMetaData()
java.lang.String	getString(int columnNumber) All columns in TransactionTable VTI is of String type.
boolean	next()
boolean	supportsMultipleInstantiations(VTIEnvironment vtiEnvironment) Find out if the ResultSet of the Table Function can be instantiated multiple times.
boolean	wasNull()

Methods inherited from class org.apache.derby.vti.VTITemplate

getBigDecimal, getBigDecimal, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getObject, getShort, getString, getTime, getTimestamp

Methods inherited from class org.apache.derby.vti.VTITemplateBase

absolute, afterLast, beforeFirst, cancelRowUpdates, clearWarnings, deleteRow, findColumn, first, getArray, getArray, getAsciiStream, getAsciiStream, getBigDecimal, getBigDecimal, getBinaryStream, getBinaryStream, getBlob, getBlob, getBoolean, getByte, getBytes, getCharacterStream, getCharacterStream, getClob, getClob, getConcurrency, getCursorName, getDate, getDate, getDate, getDouble, getFetchDirection, getFetchSize, getFloat, getInt, getLong, getObject, getObject, getObject, getRef, getRef, getRow, getShort, getStatement, getTime, getTime, getTime, getTimestamp, getTimestamp, getTimestamp, getType, getUnicodeStream, getUnicodeStream, getURL, getURL, getWarnings, insertRow, isAfterLast, isBeforeFirst, isFirst, isLast, last, moveToCurrentRow, moveToInsertRow, notImplemented, previous, refreshRow, relative, rowDeleted, rowInserted, rowUpdated, setFetchDirection, setFetchSize, updateArray, updateArray, updateAsciiStream, updateAsciiStream, updateBigDecimal, updateBigDecimal, updateBinaryStream, updateBinaryStream, updateBlob, updateBlob, updateBoolean, updateBoolean, updateByte, updateByte, updateBytes, updateBytes, updateCharacterStream, updateCharacterStream, updateClob, updateClob, updateDate, updateDate, updateDouble, updateDouble, updateFloat, updateFloat, updateInt, updateInt, updateLong, updateLong, updateNull, updateNull, updateObject, updateObject, updateObject, updateObject, updateRef, updateRef, updateRow, updateShort, updateShort, updateString, updateString, updateTime, updateTime, updateTimestamp, updateTimestamp

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.sql.ResultSet

getHoldability, getNCharacterStream, getNCharacterStream, getNClob, getNClob, getNString, getNString, getRowId, getRowId, getSQLXML, getSQLXML, isClosed, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBlob, updateBlob, updateBlob, updateBlob, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateClob, updateClob, updateClob, updateClob, updateNCharacterStream, updateNCharacterStream, updateNCharacterStream, updateNCharacterStream, updateNClob, updateNClob, updateNClob, updateNClob, updateNClob, updateNClob, updateNString, updateNString, updateRowId, updateRowId, updateSQLXML, updateSQLXML

Methods inherited from interface java.sql.Wrapper

isWrapperFor, unwrap

Field Detail

transactionTable

private TransactionInfo[] transactionTable

initialized

boolean initialized

currentRow

int currentRow

wasNull

private boolean wasNull

columnInfo

private static final ResultColumnDescriptor[] columnInfo

metadata

private static final java.sql.ResultSetMetaData metadata

Constructor Detail

TransactionTable

public TransactionTable()
                 throws StandardException

Throws:

StandardException

Method Detail

getMetaData

public java.sql.ResultSetMetaData getMetaData()

Specified by:

getMetaData in interface java.sql.ResultSet

Overrides:

getMetaData in class VTITemplateBase

See Also:

ResultSet.getMetaData()

next

public boolean next()
             throws java.sql.SQLException

Specified by:

next in interface java.sql.ResultSet

Specified by:

next in class VTITemplate

Throws:

java.sql.SQLException - if no transaction context can be found

See Also:

ResultSet.next()

close

public void close()

Specified by:

close in interface java.sql.ResultSet

Specified by:

close in class VTITemplate

See Also:

ResultSet.close()

getString

public java.lang.String getString(int columnNumber)

All columns in TransactionTable VTI is of String type.

Specified by:

getString in interface java.sql.ResultSet

Overrides:

getString in class VTITemplateBase

See Also:

ResultSet.getString(int)

wasNull

public boolean wasNull()

Specified by:

wasNull in interface java.sql.ResultSet

Overrides:

wasNull in class VTITemplateBase

See Also:

ResultSet.wasNull()

getEstimatedRowCount

public double getEstimatedRowCount(VTIEnvironment vtiEnvironment)

Description copied from interface: VTICosting

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

Specified by:

getEstimatedRowCount in interface VTICosting

Parameters:

vtiEnvironment - The state variable for optimizing the Table Function.

Returns:

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

See Also:

VTICosting.getEstimatedRowCount(org.apache.derby.vti.VTIEnvironment)

getEstimatedCostPerInstantiation

public double getEstimatedCostPerInstantiation(VTIEnvironment vtiEnvironment)

Description copied from interface: VTICosting

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

Specified by:

getEstimatedCostPerInstantiation in interface VTICosting

Parameters:

vtiEnvironment - The state variable for optimizing the Table Function.

Returns:

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

See Also:

VTICosting.getEstimatedCostPerInstantiation(org.apache.derby.vti.VTIEnvironment)

supportsMultipleInstantiations

public boolean supportsMultipleInstantiations(VTIEnvironment vtiEnvironment)

Description copied from interface: VTICosting

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

Specified by:

supportsMultipleInstantiations in interface VTICosting

Parameters:

vtiEnvironment - The state variable for optimizing the Table Function.

Returns:

false

See Also:

VTICosting.supportsMultipleInstantiations(org.apache.derby.vti.VTIEnvironment)