com.softwareag.tamino.db.api.accessor

Class TQuery

java.lang.Object

com.softwareag.tamino.db.api.accessor.TQuery

All Implemented Interfaces:

java.io.Serializable

public class TQuery
extends java.lang.Object
implements java.io.Serializable

TQuery represents a Tamino query expression. It wraps a Tamino query expression.

Version:

$Revision: 1.9 $

Author:

Marcus Schreyer

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
TQuery(java.lang.String expression) Initializes the query with the given query expression.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(java.lang.Object obj) Indicates whether some other object is "equal to" this one.
java.lang.String	getExpression() Gets the query expression.
TQuerySearchMode	getQuerySearchMode() Gets the _querysearchmode parameter for this query.
static TQuery	newInstance(java.lang.String expression) Factory method for the instantiation of a TQuery instance.
protected void	setExpression(java.lang.String expression) Sets the concrete query expression.
void	setQuerySearchMode(TQuerySearchMode querySearchMode) Sets the _querysearchmode parameter for this query.
java.lang.String	toString() Returns the String representation of this TQuery instance.

Methods inherited from class java.lang.Object

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

Constructor Detail

TQuery

public TQuery(java.lang.String expression)

Initializes the query with the given query expression.

Parameters:

expression - is the query expression.

Method Detail

newInstance

public static TQuery newInstance(java.lang.String expression)

Factory method for the instantiation of a TQuery instance.

Parameters:

expression - is the Tamino query expression.

Returns:

the TQuery instance.

setExpression

protected void setExpression(java.lang.String expression)

Sets the concrete query expression.

Parameters:

expression - is the Tamino query expression.

getExpression

public java.lang.String getExpression()

Gets the query expression.

Returns:

the Tamino query expression.

setQuerySearchMode

public void setQuerySearchMode(TQuerySearchMode querySearchMode)

Sets the _querysearchmode parameter for this query. Tamino version 4.1 onwards index access operations were made safe in the sense that they now deliver consistent results. That means, if a single query access multiple indexes, it is ensured that all these indexes reflect the same set of documents with the same document contents. For this implementation short-term locks on doctype level are used.

It has turned out that these “short-term” locks might live too long. Then, while a query request is reading indizes, concurrent updates have to wait until this short lock becomes available. To prevent starvation of these update requests, newly arriving read request have to queue up behind the update requests. As a consequence, even very short read requests need a long time until they can be processed.

To increase transaction throughput and to solve above mentioned problem we may require to process queries without these “short-term” doctype locks. But giving up the “short-term” doctype lock during index processing implies that one can no longer rely on many assumptions about the correctness of the result.

In order to specify that query request should not use "short-term" locks, set _querysearchmode=approximate i.e. TQuery.setQuerySearchMode(TQuerySearchMode.APPROXIMATE). Default value for this parameter is - "accurate"

Parameters:

_querysearchmode - parameter for this query.

getQuerySearchMode

public TQuerySearchMode getQuerySearchMode()

Gets the _querysearchmode parameter for this query.

Returns:

The _querysearchmode parameter for this query.

toString

public java.lang.String toString()

Returns the String representation of this TQuery instance.

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Indicates whether some other object is "equal to" this one.

Overrides:

equals in class java.lang.Object

Parameters:

obj - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.