com.aspc.DBObj.Internal

Class VirtualQueryHandler

java.lang.Object

com.aspc.DBObj.Internal.DBQueryHandler

com.aspc.DBObj.Internal.VirtualQueryHandler

Direct Known Subclasses:

MutableQueryHandler

public class VirtualQueryHandler
extends DBQueryHandler

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

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	DEBUG_LARGE_QUERIES_STACK environment variable to show the large queries.

Constructor Summary

Constructors

Constructor and Description
VirtualQueryHandler()

Method Summary

Modifier and Type	Method and Description
PossibleRowsHolder	fetchPossibleRows(SearchPlan sp) Fetch the possible rows for this query.
PossibleRowsHolder	tryFullSearch(SearchPlan sp) Tries to see if we have the full list of possible objects if we do then return a filtered version of that as our record set.

Methods inherited from class com.aspc.DBObj.Internal.DBQueryHandler

getKeyClause, isBottomLevel, record, tryWillSearchFail

Methods inherited from class java.lang.Object

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

Field Detail

DEBUG_LARGE_QUERIES_STACK

public static final java.lang.String DEBUG_LARGE_QUERIES_STACK

environment variable to show the large queries.

See Also:

Constant Field Values

Constructor Detail

VirtualQueryHandler

public VirtualQueryHandler()

Method Detail

fetchPossibleRows

@Nullable
 @CheckReturnValue
public PossibleRowsHolder fetchPossibleRows(@Nonnull
                                                                         SearchPlan sp)
                                                                  throws java.lang.Exception

Fetch the possible rows for this query.

Specified by:

fetchPossibleRows in class DBQueryHandler

Parameters:

sp - The search plan to use.

Returns:

The list of possible rows.

Throws:

java.lang.Exception - a serious problem.

tryFullSearch

public PossibleRowsHolder tryFullSearch(SearchPlan sp)
                                 throws java.lang.Exception

Tries to see if we have the full list of possible objects
if we do then return a filtered version of that as our record set.
Also check that we don't have a key within the clauses because this
could give a smaller result set to scan.

TODO: A large full list that we have in memory is better than a key search
that we don't have. Need some more work to work out which to use.

Parameters:

sp - the search plan.

Returns:

the possible rows holder.

Throws:

java.lang.Exception - a serious problem.