CS 525: Advanced Database Organization - Spring 2020

Assignment 3 - Record Manager

In this assignment you are creating a record manager. The record manager handles tables with a fixed schema. Clients can insert records, delete records, update records, and scan through the records in a table. A scan is associated with a search condition and only returns records that match the search condition. Each table should be stored in a separate page file and your record manager should access the pages of the file through the buffer manager implemented in the last assignment.

Hints: This assignment is much more complex than the previous assignments and it is easy to get stuck if you are unclear about how to structure your solution and what data structures to use. Sit down with a piece of paper first and design the data structures and architecture for your implementation.


This header defines basic data structures for schemas, tables, records, record ids (RIDs), and values. Furthermore, this header defines functions for serializing these data structures as strings. The serialization functions are provided (rm_serializer.c). There are four datatypes that can be used for records of a table: integer (DT_INT), float (DT_FLOAT), strings of a fixed length (DT_STRING), and boolean (DT_BOOL). All records in a table conform to a common schema defined for this table. A record is simply a record id (rid consisting of a page number and slot number) and the concatenation of the binary representation of its attributes according to the schema (data).


A schema consists of a number of attributes (numAttr). For each attribute we record the name (attrNames) and data type (dataTypes). For attributes of type DT_STRING we record the size of the strings in typeLength. Furthermore, a schema can have a key defined. The key is represented as an array of integers that are the positions of the attributes of the key (keyAttrs). For example, consider a relation R(a,b,c) where a then keyAttrs would be [0].

Data Types and Binary Representation

Values of a data type are represented using the Value struct. The value struct represents the values of a data type using standard C data types. For example, a string is a char * and an integer using a C int. Note that values are only used for expressions and for returning data to the client of the record manager. Attribute values in records are stored slightly different if the data type is string. Recall that in C a string is an array of characters ended by a 0 byte. In a record, strings are stored without the additional 0 byte in the end. For example, for strings of length 4 should occupy 4 bytes in the data field of the record.


#ifndef TABLES_H
#define TABLES_H

#include "dt.h"

// Data Types, Records, and Schemas
typedef enum DataType {
  DT_INT = 0,
  DT_STRING = 1,
  DT_FLOAT = 2,
  DT_BOOL = 3
} DataType;

typedef struct Value {
  DataType dt;
  union v {
    int intV;
    char *stringV;
    float floatV;
    bool boolV;
  } v;
} Value;

typedef struct RID {
  int page;
  int slot;
} RID;

typedef struct Record
  RID id;
  char *data;
} Record;

// information of a table schema: its attributes, datatypes, 
typedef struct Schema
  int numAttr;
  char **attrNames;
  DataType *dataTypes;
  int *typeLength;
  int *keyAttrs;
  int keySize;
} Schema;

// TableData: Management Structure for a Record Manager to handle one relation
typedef struct RM_TableData
  char *name;
  Schema *schema;
  void *mgmtData;
} RM_TableData;

#define MAKE_STRING_VALUE(result, value)				\
  do {									\
    (result) = (Value *) malloc(sizeof(Value));				\
    (result)->dt = DT_STRING;						\
    (result)->v.stringV = (char *) malloc(strlen(value) + 1);		\
    strcpy((result)->v.stringV, value);					\
  } while(0)

#define MAKE_VALUE(result, datatype, value)				\
  do {									\
    (result) = (Value *) malloc(sizeof(Value));				\
    (result)->dt = datatype;						\
    switch(datatype)							\
      {									\
      case DT_INT:							\
	(result)->v.intV = value;					\
	break;								\
      case DT_FLOAT:							\
	(result)->v.floatV = value;					\
	break;								\
      case DT_BOOL:							\
	(result)->v.boolV = value;					\
	break;								\
      }									\
  } while(0)

// debug and read methods
extern Value *stringToValue (char *value);
extern char *serializeTableInfo(RM_TableData *rel);
extern char *serializeTableContent(RM_TableData *rel);
extern char *serializeSchema(Schema *schema);
extern char *serializeRecord(Record *record, Schema *schema);
extern char *serializeAttr(Record *record, Schema *schema, int attrNum);
extern char *serializeValue(Value *val);



This header defines data structures and functions to deal with expressions for scans. These functions are implemented in expr.c. Expressions can either be constants (stored as a Value struct), references to attribute values (represented as the position of an attribute in the schema), and operator invocations. Operators are either comparison operators (equals and smaller) that are defined for all data types and boolean operators AND, OR, and NOT. Operators have one or more expressions as input. The expression framework allows for arbitrary nesting of operators as long as their input types are correct. For example, you cannot use an integer constant as an input to a boolean AND operator. As explained below, one of the parameters of the scan operation of the record manager is an expression representing the scan condition.


#ifndef EXPR_H
#define EXPR_H

#include "dberror.h"
#include "tables.h"

// datatype for arguments of expressions used in conditions
typedef enum ExprType {
} ExprType;

typedef struct Expr {
  ExprType type;
  union expr {
    Value *cons;
    int attrRef;
    struct Operator *op;
  } expr;
} Expr;

// comparison operators
typedef enum OpType {
} OpType;

typedef struct Operator {
  OpType type;
  Expr **args;
} Operator;

// expression evaluation methods
extern RC valueEquals (Value *left, Value *right, Value *result);
extern RC valueSmaller (Value *left, Value *right, Value *result);
extern RC boolNot (Value *input, Value *result);
extern RC boolAnd (Value *left, Value *right, Value *result);
extern RC boolOr (Value *left, Value *right, Value *result);
extern RC evalExpr (Record *record, Schema *schema, Expr *expr, Value **result);
extern RC freeExpr (Expr *expr);
extern void freeVal(Value *val);

#define CPVAL(_result,_input)						\
  do {									\
    (_result)->dt = _input->dt;						\
  switch(_input->dt)							\
    {									\
    case DT_INT:							\
      (_result)->v.intV = _input->v.intV;					\
      break;								\
    case DT_STRING:							\
      (_result)->v.stringV = (char *) malloc(strlen(_input->v.stringV));	\
      strcpy((_result)->v.stringV, _input->v.stringV);			\
      break;								\
    case DT_FLOAT:							\
      (_result)->v.floatV = _input->v.floatV;				\
      break;								\
    case DT_BOOL:							\
      (_result)->v.boolV = _input->v.boolV;				\
      break;								\
    }									\
} while(0)

#define MAKE_BINOP_EXPR(_result,_left,_right,_optype)			\
    do {								\
      Operator *_op = (Operator *) malloc(sizeof(Operator));		\
      _result = (Expr *) malloc(sizeof(Expr));				\
      _result->type = EXPR_OP;						\
      _result->expr.op = _op;						\
      _op->type = _optype;						\
      _op->args = (Expr **) malloc(2 * sizeof(Expr*));			\
      _op->args[0] = _left;						\
      _op->args[1] = _right;						\
    } while (0)

#define MAKE_UNOP_EXPR(_result,_input,_optype)				\
  do {									\
    Operator *_op = (Operator *) malloc(sizeof(Operator));		\
    _result = (Expr *) malloc(sizeof(Expr));				\
    _result->type = EXPR_OP;						\
    _result->expr.op = _op;						\
    _op->type = _optype;						\
    _op->args = (Expr **) malloc(sizeof(Expr*));			\
    _op->args[0] = _input;						\
  } while (0)

#define MAKE_ATTRREF(_result,_attr)					\
  do {									\
    _result = (Expr *) malloc(sizeof(Expr));				\
    _result->type = EXPR_ATTRREF;					\
    _result->expr.attrRef = _attr;					\
  } while(0)

#define MAKE_CONS(_result,_value)					\
  do {									\
    _result = (Expr *) malloc(sizeof(Expr));				\
    _result->type = EXPR_CONST;						\
    _result->expr.cons = _value;					\
  } while(0)

#endif // EXPR


We now discuss the interface of the record manager as defined in record_mgr.h. There are five types of functions in the record manager: functions for table and record manager management, functions for handling the records in a table, functions related to scans, functions for dealing with schemas, and function for dealing with attribute values and creating records. We now discuss each of these function types.

Table and Record Manager Functions

Similar to previous assignments, there are functions to initialize and shutdown a record manager. Furthermore, there are functions to create, open, and close a table. Creating a table should create the underlying page file and store information about the schema, free-space, ... and so on in the Table Information pages. All operations on a table such as scanning or inserting records require the table to be opened first. Afterwards, clients can use the RM_TableData struct to interact with the table. Closing a table should cause all outstanding changes to the table to be written to the page file. The getNumTuples function returns the number of tuples in the table.

Record Functions

These functions are used to retrieve a record with a certain RID, to delete a record with a certain RID, to insert a new record, and to update an existing record with new values. When a new record is inserted the record manager should assign an RID to this record and update the record parameter passed to insertRecord.

Scan Functions

A client can initiate a scan to retrieve all tuples from a table that fulfill a certain condition (represented as an Expr). Starting a scan initializes the RM_ScanHandle data structure passed as an argument to startScan. Afterwards, calls to the next method should return the next tuple that fulfills the scan condition. If NULL is passed as a scan condition, then all tuples of the table should be returned. next should return RC_RM_NO_MORE_TUPLES once the scan is completed and RC_OK otherwise (unless an error occurs of course). Below is an example of how a client can use a scan.

  RM_TableData *rel = (RM_TableData *) malloc(sizeof(RM_TableData));
  RM_ScanHandle *sc = (RM_ScanHandle *) malloc(sizeof(RM_ScanHandle));
  Record *r = (Record *) malloc(sizeof(Record));
  int rc;

  openTable(rel, "R");

  startScan(rel, sc, NULL);
  while((rc = next(sc, r)) == RC_OK) 
    // do something with r
    if (rc != RC_RM_NO_MORE_TUPLES)
       // handle the error

Closing a scan indicates to the record manager that all associated resources can be cleaned up.

Schema Functions

These helper functions are used to return the size in bytes of records for a given schema and create a new schema.

Attribute Functions

These functions are used to get or set the attribute values of a record and create a new record for a given schema. Creating a new record should allocate enough memory to the data field to hold the binary representations for all attributes of this record as determined by the schema.


#ifndef RECORD_MGR_H
#define RECORD_MGR_H

#include "dberror.h"
#include "expr.h"
#include "tables.h"

// Bookkeeping for scans
typedef struct RM_ScanHandle
  RM_TableData *rel;
  void *mgmtData;
} RM_ScanHandle;

// table and manager
extern RC initRecordManager (void *mgmtData);
extern RC shutdownRecordManager ();
extern RC createTable (char *name, Schema *schema);
extern RC openTable (RM_TableData *rel, char *name);
extern RC closeTable (RM_TableData *rel);
extern RC deleteTable (char *name);
extern int getNumTuples (RM_TableData *rel);

// handling records in a table
extern RC insertRecord (RM_TableData *rel, Record *record);
extern RC deleteRecord (RM_TableData *rel, RID id);
extern RC updateRecord (RM_TableData *rel, Record *record);
extern RC getRecord (RM_TableData *rel, RID id, Record *record);

// scans
extern RC startScan (RM_TableData *rel, RM_ScanHandle *scan, Expr *cond);
extern RC next (RM_ScanHandle *scan, Record *record);
extern RC closeScan (RM_ScanHandle *scan);

// dealing with schemas
extern int getRecordSize (Schema *schema);
extern Schema *createSchema (int numAttr, char **attrNames, DataType *dataTypes, int *typeLength, int keySize, int *keys);
extern RC freeSchema (Schema *schema);

// dealing with records and attribute values
extern RC createRecord (Record **record, Schema *schema);
extern RC freeRecord (Record *record);
extern RC getAttr (Record *record, Schema *schema, int attrNum, Value **value);
extern RC setAttr (Record *record, Schema *schema, int attrNum, Value *value);

#endif // RECORD_MGR_H

Optional Extensions

You can earn up to 20 bonus points for implementing optional extensions. A good implementation of one or two extensions will give you the maximum of 20 points. So rather then implementing 5 incomplete extensions, I suggest you to focus on one extension first and if there is enough time, then add additional ones.

Source Code Structure

You source code directories should be structured as follows. You should reuse your existing storage manager and buffer manager implementations. So before you start to develop, please copy your storage manager and buffer manager implementations. E.g., the structure may look like that:

Test Cases


Defines several helper methods for implementing test cases such as ASSERT_TRUE.


This file implements several test cases using the expr.h interface. Please let your make file generate a test_expr binary for this code. You are encouraged to extend it with new test cases or use it as a template to develop your own test files.


This file implements several test cases using the record_mgr.h interface. Please let your make file generate a test_assign3 binary for this code. You are encouraged to extend it with new test cases or use it as a template to develop your own test files.