HashDriver.java

import simpledb.server.*;
import simpledb.index.*;
import simpledb.index.hash.*;
import simpledb.query.*;
import simpledb.record.RID;
import simpledb.record.Schema;
import simpledb.record.TableInfo;
import simpledb.tx.Transaction;
import java.util.Scanner;

public class HashDriver{

	private static Schema idxsch = new Schema();
	private static Schema messySch = new Schema();
	private static Transaction tx;
	private static Transaction tx2;
	private static TableScan ts;
   
	public static void main(String[] args) {
	  SimpleDB.init("studentdb");    
	  System.out.println("BUILD LINEAR HASH INDEX");
	  tx = new Transaction();
	  tx2 = new Transaction();
	  // Defines the schema for an index record for Col2 of the messy table 
	  idxsch.addStringField("dataval",64);
	  idxsch.addIntField("block");
	  idxsch.addIntField("id"); 
	  messySch.addIntField("col1");
	  messySch.addStringField("col2",64);
	  // Builds a Linear Hash Index on Col2 of the messy table 
	  LinearHash idx = new LinearHash("hashIdxTest", idxsch, tx);
	  Plan p = new TablePlan("messy", tx);
	  UpdateScan s = (UpdateScan) p.open();
	  while (s.next()){
	      idx.insert(s.getVal("col2"), s.getRid());
	  }
	  s.close();
	  Scanner scan = new Scanner(System.in);
	  while(true){
		  System.out.println("Enter searchkey: (q to quit)");
		  String str = scan.next();
		  if((str.equals("q"))||(str.equals("quit"))){
			  break;
		  }
		  Constant searchkey = new StringConstant(str);
		  RID rid = idx.search(searchkey);
		  if (rid==null){
			  System.out.println("Not Found");
		  }
		  else{
			  String tblname = "messy";
		      TableInfo ti = new TableInfo(tblname, messySch);
		      ts = new TableScan(ti, tx2);
		      ts.moveToRid(rid);
		      System.out.println(ts.getInt("col1")+"\t"+ts.getVal("col2"));
		      ts.close();
		  }
	  }
	  idx.close();
	  tx.rollback();
	  tx2.rollback();
	}
}