org.apache.derby.iapi.sql.execute.xplain
Interface XPLAINFactoryIF

All Known Implementing Classes:
XPLAINFactory

public interface XPLAINFactoryIF

This is the factory interface of the XPLAINFactory facility. It extends the possibilities and provides a convenient protocol to explain queries on basis of the query execution plan. This plan manfifests in Derby in the different ResultSets and their associated statistics. The introduction of this factory interface makes it possible to switch to another implementation or to easily extend the API.


Field Summary
static java.lang.String MODULE
          Module name for the monitor's module locating system.
 
Method Summary
 void freeResources()
          This method gets called when the user switches off the explain facility.
 XPLAINVisitor getXPLAINVisitor()
          This method returns an appropriate visitor to traverse the ResultSetStatistics.
 

Field Detail

MODULE

static final java.lang.String MODULE
Module name for the monitor's module locating system.

See Also:
Constant Field Values
Method Detail

getXPLAINVisitor

XPLAINVisitor getXPLAINVisitor()
                               throws StandardException
This method returns an appropriate visitor to traverse the ResultSetStatistics. Depending on the current configuration, the perfect visitor will be chosen, created and cached by this factory method.

Returns:
a XPLAINVisitor to traverse the ResultSetStatistics
Throws:
StandardException
See Also:
XPLAINVisitor

freeResources

void freeResources()
This method gets called when the user switches off the explain facility. The factory destroys for example the cached visitor implementation(s) or releases resources to save memory.


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