package simpledb;

import java.util.*;
import java.io.*;

/**
 * The interface for database files on disk .
 * Database files need to be able to fetch pages and iterate through tuples.
 * They may also support sargable predictes for efficient index searches.
 *
 * DbFile's are generally access through the buffer pool (rather than
 * directly by operators.)
 */
public interface DbFile {
    /**
     * Read the specified page from disk. 
     *
     * @throws NoSuchElementException if the page does not exist in this file
     */
    public Page readPage(PageId id) throws NoSuchElementException;
    
    /**
     * Push the specified page to disk.
     * This page must have been previously read from this file via a call to
     * readPage. 
     *
     * @throws IOException if the write fails
     *       
     */
    public void writePage(Page p) throws IOException;
    
    /**
     * Adds the specified tuple to the file on behalf of transaction.
     * This method will acquire a lock on the affected pages of the file, and
     * may block until the lock can be acquired.
     *
     * @param tid The transaction performing the update
     * @param t The tuple to add.  This tuple will be updated to reflect that
     *          it is now stored in this file.
     * @throws DbException if the tuple cannot be added
     * @throws IOException if the needed file can't be read/written
     */
    public Vector<Page> addTuple(TransactionId tid, Tuple t) 
	throws DbException, IOException, TransactionAbortedException;
    
    /**
     * Removes the specifed tuple from the file on behalf of the specified
     * transaction.
     * This method will acquire a lock on the affected pages of the file, and
     * may block until the lock can be acquired.
     *
     * @throws DbException if the tuple cannot be deleted or is not a member
     *   of the file
     */
    public Page deleteTuple(TransactionId tid, Tuple t) 
	throws DbException, TransactionAbortedException;

    public DbFileIterator iterator(TransactionId tid);
    
    /**
     * Returns a table id for this table.
     */
    public int id();

}