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Class COM.cloudscape.vti.LockTable

java.lang.Object
    |
    +----COM.cloudscape.vti.VTITemplate
            |
            +----COM.cloudscape.vti.LockTable

public class LockTable
extends VTITemplate
implements VTICosting
Copyright © 1998-2000, Informix Software, Inc. All rights reserved.

LockTable is a virtual table which shows all the locks currently held in the database. This virtual table can be invoked by calling it directly

 select * from new COM.cloudscape.vti.LockTable() t; 
or through the system alias TransactionTable
 select * from new LockTable() t; 

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

The LockTable virtual table has the following columns:


Variable Index

 o ALL
return all locks and latches
 o LATCH
return only latches
 o TABLE_AND_ROWLOCK
return only table and row locks

Constructor Index

 o LockTable()
The normal way of instantiating a LockTable, equivalent to LockTable(COM.cloudscape.vti.LockTable->TABLE_AND_ROWLOCK).
 o LockTable(int)
This call is intrusive and should only be used under the supervision of cloudscape tech support.

Method Index

 o close()
 
 o getEstimatedCostPerInstantiation(VTIEnvironment)
 
 o getEstimatedRowCount(VTIEnvironment)
 
 o getMetaData()
 
 o getString(int)
All columns in TransactionTable VTI are of String type.
 o next()
 
 o supportsMultipleInstantiations(VTIEnvironment)
 
 o wasNull()
 

Field Detail

 o LATCH
public static final int LATCH
          return only latches
 o TABLE_AND_ROWLOCK
public static final int TABLE_AND_ROWLOCK
          return only table and row locks
 o ALL
public static final int ALL
          return all locks and latches

Constructor Detail

 o LockTable
public LockTable()
          The normal way of instantiating a LockTable, equivalent to LockTable(COM.cloudscape.vti.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 cloudscape users. Only under abnormal circumstances will one be interested in looking at latches.
 o LockTable
public LockTable(int flag)
          This call is intrusive and should only be used under the supervision of cloudscape tech support. Create an instance of the lock table which has transient latches as well as locks.

Method Detail

 o getMetaData
public java.sql.ResultSetMetaData getMetaData()
See Also:
getMetaData
 o next
public boolean next() throws java.sql.SQLException
Throws:
java.sql.SQLException - if no transaction context can be found, or other cloudscape internal errors are encountered.
See Also:
next
 o close
public void close()
See Also:
close
 o getString
public java.lang.String getString(int columnNumber)
          All columns in TransactionTable VTI are of String type.
Overrides:
getString in class VTITemplate
See Also:
getString
 o wasNull
public boolean wasNull()
Overrides:
wasNull in class VTITemplate
See Also:
wasNull
 o getEstimatedRowCount
public double getEstimatedRowCount(VTIEnvironment vtiEnvironment)
See Also:
getEstimatedRowCount
 o getEstimatedCostPerInstantiation
public double getEstimatedCostPerInstantiation(VTIEnvironment vtiEnvironment)
See Also:
getEstimatedCostPerInstantiation
 o supportsMultipleInstantiations
public boolean supportsMultipleInstantiations(VTIEnvironment vtiEnvironment)
Returns:
false
See Also:
supportsMultipleInstantiations

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