com.sun.mdm.index.query
Class QueryPipeLine

java.lang.Object
  com.sun.mdm.index.query.QueryPipeLine

All Implemented Interfaces:

AssemblerEngine

class QueryPipeLine

extends java.lang.Object

implements AssemblerEngine

Splits the QueryObject into multiple QueryObjects and invokes QueryManager to execute and return back QMIterator QueryPipeLine executes the query in these stages. • 1: create QueryObject to select only primary keys for primary object. Invoke QueryManager.execute() to get ids. • 2: Divide the ids received from step 1 into multiples of fetchsize and create Queryobjects based on the original queryobject received in step 1. Add IN condition containing fetch ids to the original queryobject and invoke QueryManager.executeAssemble. It replaces the AssemblerEngine in QMIterator received from QueryManager.execute by itself. Acting as AssemblerEngine, QueryPipeLine delegates its AssmblerEngine methods invocations to the original AssemblerEngine, specified in the QueryObject. So QueryPipeLine acts as lazy query executer that executes more queryobjects when set of data returned by previous QueryObject is exhausted.

Constructor Summary

(package private)

QueryPipeLine()

Method Summary

java.lang.Object	clone() clones the AssemblerEngine
void	close() This will close the JDBC resultsets.
(package private) QMIterator	executeAssemble(QueryObject qobject) This method will execute the query(s) specified in QueryObject and also use FactoryEngine for creating composite objects.
(package private) AssemblerEngine	getOriginalAssemblerEngine(QMIterator iterator) An Iterator's assemblerEngine may be already susbstituted by QueryPipeLine(in case we get the QMIterator from QueryObjectCache).
boolean	hasNext() returns true or false if next object can be retrieved
void	initCompile(SQLDescriptor[] sqlDesc, AssembleDescriptor assDesc)
void	initRun(java.sql.Connection con, java.sql.ResultSet[] resultSets, java.sql.Statement[] statements, int maxRows)
void	initRun(java.sql.Connection con, java.sql.ResultSet[] resultSets, java.sql.Statement[] statements, int maxRows, boolean closeDbConnection) This method initializes the data structures that are used during run time and can be writeable.
java.lang.Object	next() This will retrieve next composite object constructed by AssemblerEngine.

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryPipeLine

QueryPipeLine()
        throws CreateException

Method Detail

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

clones the AssemblerEngine

Specified by:

clone in interface AssemblerEngine

Returns:

clone of this engine

Throws:

java.lang.CloneNotSupportedException - CloneNotSupportedException

close

public void close()
           throws QMException

This will close the JDBC resultsets.

Specified by:

close in interface AssemblerEngine

Throws:

QMException - QMException

executeAssemble

QMIterator executeAssemble(QueryObject qobject)
                     throws QMException

This method will execute the query(s) specified in QueryObject and also use FactoryEngine for creating composite objects.

Parameters:

qobject - QueryObject that contains description of query

Returns:

QMIterator iterator that is used to fetch each composite object.

Throws:

QMException - QMException

getOriginalAssemblerEngine

AssemblerEngine getOriginalAssemblerEngine(QMIterator iterator)

An Iterator's assemblerEngine may be already susbstituted by QueryPipeLine(in case we get the QMIterator from QueryObjectCache). So we want to get the AssemblerEngine of an Iterator, that was set before replacement by QueryPipleLine. So we want to get AssemblerEngine that does the core Assembling process. Otherwise we might end up in an endless recursion of executing queries

Parameters:

iterator -

Returns:

hasNext

public boolean hasNext()
                throws QMException

returns true or false if next object can be retrieved

Specified by:

hasNext in interface AssemblerEngine

Returns:

true or false

Throws:

QMException - QMException

initCompile

public void initCompile(SQLDescriptor[] sqlDesc,
                        AssembleDescriptor assDesc)
                 throws QMException

Description copied from interface: AssemblerEngine

This is used during compilation and any data structures are cached. So the data strcutures should be read only and can be shared.

Specified by:

initCompile in interface AssemblerEngine

Parameters:

sqlDesc - SQLDescriptor[] that contains SQL statements and their meta data to be used for initialization.

assDesc - AssembleDescriptor

Throws:

QMException - QMException

initRun

public void initRun(java.sql.Connection con,
                    java.sql.ResultSet[] resultSets,
                    java.sql.Statement[] statements,
                    int maxRows)
             throws QMException

Description copied from interface: AssemblerEngine

This initialization is used during run time. QueryManager passes Connection and ResultSet[] to the AssemblerEngine so that AssemblerEngine can retrieve data from the database and compose the objects.

Specified by:

initRun in interface AssemblerEngine

Parameters:

con - Connection

resultSets - ResultSet[]

statements - Statement[]

Throws:

QMException - QMException

initRun

public void initRun(java.sql.Connection con,
                    java.sql.ResultSet[] resultSets,
                    java.sql.Statement[] statements,
                    int maxRows,
                    boolean closeDbConnection)
             throws QMException

This method initializes the data structures that are used during run time and can be writeable.

Specified by:

initRun in interface AssemblerEngine

Parameters:

con - Connection

resultSets - ResultSet[]

statements - Statement[]

maxRows - maximum number of rows

closeDbConnection - set to true if the database connection is to be closed by the AssemblerEngine, false if some other calling class is to close the database connection instead.

Throws:

QMException - QMException

next

public java.lang.Object next()
                      throws QMException

This will retrieve next composite object constructed by AssemblerEngine. The subclass of QMIterator should call super.next() to retrieve next composite object.

Specified by:

next in interface AssemblerEngine

Returns:

next Object

Throws:

QMException - QMException