com.aspc.DBObj.Internal

Class DBQueryHandler

java.lang.Object

com.aspc.DBObj.Internal.DBQueryHandler

Direct Known Subclasses:

ArchiveQueryHandler, ForkJoinQueryHandler, VirtualQueryHandler

public abstract class DBQueryHandler
extends java.lang.Object

Handles the actual database query. The handle must return a list of rows id's that MAY match. We'll do a filter on all the rows returned so as long as the row list contain all possible matches we'll be OK. Obviously the fewer/closer the match the better the performance will be. THREAD MODE: MULTI-THREADED

Since:

March 16, 2002, 5:54 PM

Author:

Nigel Leck

Constructor Summary

Constructors

Constructor and Description
DBQueryHandler()

Method Summary

Modifier and Type	Method and Description
abstract PossibleRowsHolder	fetchPossibleRows(SearchPlan plan)
protected DBPathClause	getKeyClause(SearchPlan plan) If a specific key has been requested as part of the criteria then we can create a query clause to directly access the specific data
protected boolean	isBottomLevel(VirtualDB vDB, DBClass dbClass, DBCriteria criteria) If the class that you are searching for or the field that you are searching with is defined in this layer then no point searching any deeper.
static void	record(DataSource ds, java.lang.String message, java.lang.Object rows, long start) Record the info into the timings files.
protected PossibleRowsHolder	tryWillSearchFail(SearchPlan plan) Will this search fail ? 1) If the searched class is excluded from all layers 2) Is the bottom level above the first non excluded layer ?

Methods inherited from class java.lang.Object

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

Constructor Detail

DBQueryHandler

public DBQueryHandler()

Method Detail

fetchPossibleRows

public abstract PossibleRowsHolder fetchPossibleRows(SearchPlan plan)
                                              throws java.lang.Exception

Parameters:

plan -

Returns:

the value

Throws:

java.lang.Exception - a serious problem

getKeyClause

protected DBPathClause getKeyClause(SearchPlan plan)

If a specific key has been requested as part of the criteria then we can create a query clause to directly access the specific data

Parameters:

plan -

Returns:

the value

record

public static void record(@Nonnull
                          DataSource ds,
                          java.lang.String message,
                          java.lang.Object rows,
                          long start)

Record the info into the timings files.

Parameters:

ds - the data source

message - the message

rows -

start -

tryWillSearchFail

protected PossibleRowsHolder tryWillSearchFail(SearchPlan plan)

Will this search fail ? 1) If the searched class is excluded from all layers 2) Is the bottom level above the first non excluded layer ?

Parameters:

plan -

Returns:

the value

isBottomLevel

protected boolean isBottomLevel(VirtualDB vDB,
                                DBClass dbClass,
                                DBCriteria criteria)

If the class that you are searching for or the field that you are searching with is defined in this layer then no point searching any deeper.

Parameters:

vDB - the layer

dbClass - the class

criteria - the criteria

Returns:

the value