IUnionHandler Class Reference

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

List of all members.

Public Member Functions

virtual SharedPtr
< DSIExtResultSet
Passdown (AEUnion *in_node)=0
 Pass down the given UNION operation.
virtual ~IUnionHandler ()

Protected Member Functions

 IUnionHandler ()

Detailed Description

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

A relational UNION operation combines the results of two or more queries into a single result set that include all the rows that belong to all queries in the union.

Basically, if both relational operations proceeding an UNION relational operation are successfully passed down, the UNION operation can be passed down.

Simba SQLEngine will always attempt to pass down both queries before attempting to pass down UNION. In other words, the handler to perform UNION pass-down will never be invoked if any of the queries are not passed down successfully.

Constructor & Destructor Documentation

virtual ~IUnionHandler (  )  [inline, virtual]


IUnionHandler (  )  [inline, protected]


Member Function Documentation

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

Pass down the given UNION operation.

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

in_node The union operation node. Cannot be NULL. (NOT OWN)
the table that represents the union result if successful, NULL otherwise.

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

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