Select Class Reference

#include <select.h>

Inheritance diagram for Select:

Collaboration diagram for Select:

Public Member Functions
	Select (FileId rel_id, FileId result_id, std::vector< FieldId > fields, std::vector< Comp > comps, std::vector< void * > values, Catalog *catalog)
	Constructor for Select operation. Both FileScan and IndexScan use this constructor.
	~Select ()
	Destructor for the Select Operation.
Public Member Functions inherited from Operation
	Operation (FileId result_id, Catalog *catalog)
	Constructor for the Operation class. Because Operation is an abstract class, an object cannot be created, but this constructor is used by derived classes.
virtual	~Operation ()
	Destructor for the Operation class. Cleans up dynamic memory in result state.
virtual void	runOperation ()=0
	Runs the operation. Other than initial setup in the initialization, all the work of each operation is done in this function. It is a pure virtual method, and is implemented in inherited classes. All child classes must implement this method.

Protected Attributes
std::vector< FieldId >	fields
std::vector< Comp >	comps
std::vector< void * >	values
fileState	file_state
Protected Attributes inherited from Operation
fileState	result_state
Catalog *	catalog

Additional Inherited Members
Protected Member Functions inherited from Operation
void	_initState (FileId file_id, std::vector< FieldId > fields, fileState *state)
	Performs the file and temporary record setup for relational operators.
void	_delState (fileState *file_state)
	Deletes objects created in relop structs.

Detailed Description

Select is an abstract class that lays the foundation for select operations

Constructor & Destructor Documentation

Select()

Select::Select	(	FileId	rel_id,
		FileId	result_id,
		std::vector< FieldId >	fields,
		std::vector< Comp >	comps,
		std::vector< void * >	values,
		Catalog *	catalog
	)

Constructor for Select operation. Both FileScan and IndexScan use this constructor.

Parameters

rel_id.	FileId of the relation file.
result_id.	FileId of the result file.
fields.	Vector of field ids for the select operation. Note: the fieldId values are positions/indexes of the fields
comps.	Vector of Comps for the select operation.
values.	Vector of Void * for the select operation.
catalog.	pointer to the catalog of SwatDB

Precondition

file_name is the name of a valid file.

Postcondition

private variables have been set accordingly.

Exceptions

MismatchingFieldsRelOpsManager

if the fields parameter has incorrect fields or if there are mismatching numbers of fields, values, or comps

Member Data Documentation

comps

std::vector<Comp> Select::comps

protected

comparators used in the select operation

fields

std::vector<FieldId> Select::fields

protected

The positions of the following three vectors are lined up, so index 0 of each are one conjunct of the select, index 1 is the next, and so on. Fields used in the select operation

values

std::vector<void *> Select::values

protected

Values used in the select operation. Type is void * because this could be a mix of float, int, and char * types.

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

• select.h