ITopHandler Class Reference

Defines the interface for passing down a relational TOP operation to the DSII. More...

Inherited by DSIExtAbstractTopHandler.

List of all members.

Public Member Functions

virtual SharedPtr
< DSIExtResultSet
Passdown (AETop *in_node)=0
 Pass down the given TOP N operation.
virtual ~ITopHandler ()
 Destructor.

Protected Member Functions

 ITopHandler ()
 Constructor.

Detailed Description

Defines the interface for passing down a relational TOP operation to the DSII.

A relational TOP operation limits the rows returned in a query result set to a specified number of rows. When TOP is used in conjunction with the ORDER BY clause, the result set is limited to the first N number of ordered rows; otherwise, it returns the first N number of rows in an undefined order.

Simba SQLEngine attempts to pass down the operand before attempting to pass down TOP. In other words, the handler to perform TOP pass-down will never be invoked if the operand is not passed down successfully.

A relational TOP operation can be either TOP N or TOP N PERCENT.


Constructor & Destructor Documentation

virtual ~ITopHandler (  )  [inline, virtual]

Destructor.

ITopHandler (  )  [inline, protected]

Constructor.


Member Function Documentation

virtual SharedPtr<DSIExtResultSet> Passdown ( AETop in_node  )  [pure virtual]

Pass down the given TOP N operation.

An implementation should ensure that this method returns the table representing the TOP N result if the operation is successfully passed down. Otherwise, it should return NULL and in_node remains intact.

Parameters:
in_node The TOP operation node. Cannot be NULL. (NOT OWN)
Returns:
The table that represents TOP N result if it is passed down successful, NULL otherwise.

Implemented in DSIExtAbstractTopHandler.


The documentation for this class was generated from the following file:

Generated on Wed May 17 14:21:18 2017 for SimbaEngine 10.1.3.1011 by simba