iterator
Class NestedLoopsJoins

java.lang.Object
  iterator.Iterator
      iterator.NestedLoopsJoins

All Implemented Interfaces:

Flags

public class NestedLoopsJoins

extends Iterator

This file contains an implementation of the nested loops join algorithm as described in the Shapiro paper. The algorithm is extremely simple: foreach tuple r in R do foreach tuple s in S do if (ri == sj) then add (r, s) to the result.

Field Summary

Fields inherited from class iterator.Iterator

closeFlag

Fields inherited from interface global.Flags

DEBUG, TEST

Constructor Summary

NestedLoopsJoins(AttrType[] in1, int len_in1, short[] t1_str_sizes, AttrType[] in2, int len_in2, short[] t2_str_sizes, int amt_of_mem, Iterator am1, java.lang.String relationName, CondExpr[] outFilter, CondExpr[] rightFilter, FldSpec[] proj_list, int n_out_flds)
constructor Initialize the two relations which are joined, including relation type,

Method Summary

void	close() implement the abstract method close() from super class Iterator to finish cleaning up
Tuple	get_next() abstract method, every subclass must implement it.

Methods inherited from class iterator.Iterator

free_buffer_pages, get_buffer_pages

Methods inherited from class java.lang.Object

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

Constructor Detail

NestedLoopsJoins

public NestedLoopsJoins(AttrType[] in1,
                        int len_in1,
                        short[] t1_str_sizes,
                        AttrType[] in2,
                        int len_in2,
                        short[] t2_str_sizes,
                        int amt_of_mem,
                        Iterator am1,
                        java.lang.String relationName,
                        CondExpr[] outFilter,
                        CondExpr[] rightFilter,
                        FldSpec[] proj_list,
                        int n_out_flds)
                 throws java.io.IOException,
                        NestedLoopException

constructor Initialize the two relations which are joined, including relation type,

Parameters:

in1 - Array containing field types of R.

len_in1 - # of columns in R.

t1_str_sizes - shows the length of the string fields.

in2 - Array containing field types of S

len_in2 - # of columns in S

t2_str_sizes - shows the length of the string fields.

amt_of_mem - IN PAGES

am1 - access method for left i/p to join

relationName - access hfapfile for right i/p to join

outFilter - select expressions

rightFilter - reference to filter applied on right i/p

proj_list - shows what input fields go where in the output tuple

n_out_flds - number of outer relation fileds

Throws:

java.io.IOException - some I/O fault

NestedLoopException - exception from this class

Method Detail

get_next

public Tuple get_next()
               throws java.io.IOException,
                      JoinsException,
                      index.IndexException,
                      InvalidTupleSizeException,
                      InvalidTypeException,
                      PageNotReadException,
                      TupleUtilsException,
                      PredEvalException,
                      SortException,
                      LowMemException,
                      UnknowAttrType,
                      UnknownKeyTypeException,
                      java.lang.Exception

Description copied from class: Iterator

abstract method, every subclass must implement it.

Specified by:

get_next in class Iterator

Returns:

The joined tuple is returned

Throws:

java.io.IOException - I/O errors

JoinsException - some join exception

index.IndexException - exception from super class

InvalidTupleSizeException - invalid tuple size

InvalidTypeException - tuple type not valid

PageNotReadException - exception from lower layer

TupleUtilsException - exception from using tuple utilities

PredEvalException - exception from PredEval class

SortException - sort exception

LowMemException - memory error

UnknowAttrType - attribute type unknown

UnknownKeyTypeException - key type unknown

java.lang.Exception - other exceptions

close

public void close()
           throws JoinsException,
                  java.io.IOException,
                  index.IndexException

implement the abstract method close() from super class Iterator to finish cleaning up

Specified by:

close in class Iterator

Throws:

java.io.IOException - I/O error from lower layers

JoinsException - join error from lower layers

index.IndexException - index access error