/Users/green/Documents/workspace/DavisDB_public/QueryEngine.h

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/*
 * QueryEngine.h
 *
 *  Created on: May 3, 2010
 *      Author: green
 */

#ifndef QUERYENGINE_H_
#define QUERYENGINE_H_

#include "Common.h"
#include "IQueryOperator.h"
#include "RecordFileScan.h"
#include "SystemManager.h"

struct RelationAttribute {
        char relName[MAX_RELATION_NAME];                
        char attrName[MAX_ATTRIBUTE_NAME];              
};

struct TypedValue {
        AttributeType type;     
        union {                                 
                int i;          
                float f;                
                const char* str;
        };
};

struct AttributeOrValue {
        bool isAttribute;       
        union {
                RelationAttribute attribute; 
                TypedValue value;                        
        };
};

struct Condition {
        RelationAttribute left; 
        ComparisonOp op;                
        AttributeOrValue right; 
};

class QueryEngine {
public:
        static QueryEngine* getInstance();

        ReturnCode select(int nAttributes, const RelationAttribute attributes[],
                                      int nRelations, const char* relations[],
                                      int nConditions, const Condition conditions[]);

        ReturnCode insert(const char* relName, int nValues, 
                                          const TypedValue values[]);

        ReturnCode remove(const char* relName, int nConditions,
                        const Condition conditions[]);

        ReturnCode update(const char* relName, const RelationAttribute* left,
                                          const AttributeOrValue* right, int nConditions, 
                                          const Condition conditions[]);

private:
        // BEGIN private methods and data related to sample implementation of
        // QueryEngine::select; you may use these, change them, or delete them as
        // you like.
        ReturnCode buildScanNode(const char* relation, IQueryOperator** scan);
        
        ReturnCode buildProjectNode(IQueryOperator* child, int nAttributes,
                                                                const RelationAttribute attributes[],
                                                                IQueryOperator** project);
        
        ReturnCode buildExecutionPlan(int nAttributes, const RelationAttribute attributes[],
                                                                  int nRelations, const char* relations[],
                                                                  int nConditions, const Condition conditions[],
                                                                  IQueryOperator** root);
        uint getRecordSize(int nAttributes, const RelationAttributeInfo attributes[]);
        
        SystemManager* sm_;
        RecordManager* rm_;
        // END private methods and data related to sample implementation of QueryEngine::select

        bool isQueryPlansOn();
        
        QueryEngine();
        ~QueryEngine();

};

#endif /* QUERYENGINE_H_ */

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