Schema Class Reference

#include <schema.h>

Public Member Functions
	Schema ()=delete
	Disable default Constructor.
	Schema (const Schema &other)
	Disable copy assignment constructor.
	Schema (std::vector< FieldEntry > field_list, std::vector< std::string > primary_key)
	Constructor of Schema.
	Schema (std::ifstream *in_file)
	Schema Constructor that initializes schema based on saved metadata.
	~Schema ()
	Destructor.
std::string	getFieldName (FieldId field_id)
FieldId	getFieldId (std::string field_name)
	getter function for the FieldId associated with a field name.
FieldType	getFieldType (FieldId field_id)
	returns the field type given a field_id
void	saveToFile (std::ofstream *out_file)
	save schema metadata to a file.
void	printFields ()

Private Attributes
std::unordered_map< std::string, FieldId >	field_map
std::vector< FieldEntry >	field_list
std::vector< FieldId >	primary_key

Friends
class	IndexFile
class	RelOpsManager
class	Select
class	Record
class	Key
class	SearchKeyFormat
class	SwatDB
class	FileManager

Detailed Description

SwatDB Schema Class. This is a class to represent the schema for a relation. It stores data structures, including mapping from field names to FieldId, field types, etc , reverse mapping from FieldId to field names, and list of primary keys. This is also a class used to represent key format. Strictly speaking, key format is DIFFERENT from relation schema, but as the data strcuctures used to represent the two are very similar, a common class is used in SwatDB for simplicity.

Constructor & Destructor Documentation

Schema() [1/3]

Schema::Schema

(

const Schema &

other

)

Disable copy assignment constructor.

Copy assignment constructor.

Schema() [2/3]

Schema::Schema	(	std::vector< FieldEntry >	field_list,
		std::vector< std::string >	primary_key
	)

Constructor of Schema.

Precondition

Valid field_list, a vector of FieldEntry and valid vector of field names for primary key are provided

Postcondition

The field_list and primary_key are initialized.

Exceptions

InvalidFieldNameSchema

if the the length of any field name exceeds MAX_FIELD_NAME.

Schema() [3/3]

Schema::Schema

(

std::ifstream *

in_file

)

Schema Constructor that initializes schema based on saved metadata.

Parameters

in_file

std::ifsream* to read from.

Postcondition

The field_list and primary_key are initialized from the metadata file. The assumed format is:

Number of Fields Field Name for Field 0 Field Type for Field 0 (integer associated with FieldType data type) Max Size for Field 0 (in bytes) Field Name for Field 1 Field Type for Field 1(integer associated with FieldType data type) Max Size for Field 1 ... Number of Primary Key Fields FieldId for first field FieldId for second field ...

Example:

3 StudentId 0 4 Name 3 256 Gpa 2 4 1 0

This is the format that the saveToFile function outputs.

Member Function Documentation

getFieldType()

FieldType Schema::getFieldType

(

FieldId

field_id

)

returns the field type given a field_id

Parameters

FieldId

field_id corresponds to desired field

Returns

FieldType of desired field_id

printFields()

void Schema::printFields

(

)

NOTE: THIS METHOD IS FOR DEBUGGING ONLY

saveToFile()

void Schema::saveToFile

(

std::ofstream *

out_file

)

save schema metadata to a file.

Saves data in this format: Num fields name – type | for each field max_size – (field_id implicit in order) ...

Num Primary Key Fields field ids ] in order

Parameters

out_file

std::ofsream* to output to.

Friends And Related Symbol Documentation

IndexFile

friend class IndexFile

friend

IndexFile has access to private fields of Schema.

Member Data Documentation

field_list

std::vector<FieldEntry> Schema::field_list

private

This vector is a maintains the list of FieldEntry, which stores field name, FieldType and max length of each field.

field_map

std::unordered_map<std::string, FieldId> Schema::field_map

private

Mapping from field name to FieldId

primary_key

std::vector<FieldId> Schema::primary_key

private

This is the vector of field identifiers that make up the primary key fields. No two records can have identical primary key values.

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

• schema.h