Class Catalog

java.lang.Object

Catalog

public class Catalog
extends Object

A class representing the catalog of a simple relational database. It stores all per-table metadata: the name of the table, and the metadata for each of the table's columns. To allow access to the catalog methods from all other classes, we make all methods static, so that the class name can be used to invoke them.

Field Summary

Fields

Modifier and Type	Field and Description
static String	CATALOG_NAME The name of the catalog's underlying BDB database.

Constructor Summary

Constructors

Constructor and Description
Catalog()

Method Summary

Modifier and Type	Method and Description
static void	close() Closes the catalog and ensures all changes have been written to disk.
static OperationStatus	getMetadata(Table table) Reads the entry for the specified table from the catalog of metadata and adds the column information to the Table object.
static void	open() Opens the catalog so that it can be used to store and retrieve metadata.
static OperationStatus	putMetadata(Table table) Adds an entry to the catalog for the specified table.
static OperationStatus	removeMetadata(Table table) Removes the entry for the specified table from the catalog of metadata.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CATALOG_NAME

public static final String CATALOG_NAME

The name of the catalog's underlying BDB database.

See Also:

Constant Field Values

Constructor Detail

Catalog

public Catalog()

Method Detail

open

public static void open()
                 throws DatabaseException,
                        FileNotFoundException

Opens the catalog so that it can be used to store and retrieve metadata.

Throws:

DatabaseException - if Berkeley DB encounters a problem opening the underlying database.

FileNotFoundException - if the Berkeley DB cannot access the catalog's database file.

close

public static void close()
                  throws DatabaseException

Closes the catalog and ensures all changes have been written to disk.

Throws:

DatabaseException - if Berkeley DB encounters a problem closing the underlying database.

putMetadata

public static OperationStatus putMetadata(Table table)
                                   throws DeadlockException,
                                          DatabaseException,
                                          IOException

Adds an entry to the catalog for the specified table.

Parameters:

table - the table whose metadata we need to add

Returns:

OperationStatus.KEYEXIST if there is already a table with the same name, and OperationStatus.SUCCESS otherwise.

Throws:

DeadlockException - if deadlock occurs while accessing the catalog's underlying database.

DatabaseException - if Berkeley DB encounters another problem accessing the catalog's underlying database.

IOException

getMetadata

public static OperationStatus getMetadata(Table table)
                                   throws DatabaseException,
                                          DeadlockException

Reads the entry for the specified table from the catalog of metadata and adds the column information to the Table object.

Parameters:

table - the table whose metadata we need to retrieve

Returns:

OperationStatus.NOTFOUND if the table is not in the catalog, and OperationStatus.SUCCESS otherwise.

Throws:

DeadlockException - if deadlock occurs while accessing the catalog's underlying database.

DatabaseException - if Berkeley DB encounters another problem accessing the catalog's underlying database.

removeMetadata

public static OperationStatus removeMetadata(Table table)
                                      throws DeadlockException,
                                             DatabaseException

Removes the entry for the specified table from the catalog of metadata.

Parameters:

table - the table whose metadata we need to remove

Returns:

OperationStatus.NOTFOUND if the table is not in the catalog, and OperationStatus.SUCCESS otherwise.

Throws:

DeadlockException - if deadlock occurs while accessing the catalog's underlying database.

DatabaseException - if Berkeley DB encounters another problem accessing the catalog's underlying database.