iterator
Class SortMerge

java.lang.Object
  iterator.Iterator
      iterator.SortMerge

All Implemented Interfaces:

Flags, GlobalConst

public class SortMerge

extends Iterator

implements GlobalConst

This file contains the interface for the sort_merg joins. We name the two relations being joined as R and S. This file contains an implementation of the sort merge join algorithm as described in the Shapiro paper. It makes use of the external sorting utility to generate runs, and then uses the iterator interface to get successive tuples for the final merge.

Field Summary

Fields inherited from class iterator.Iterator

closeFlag

Fields inherited from interface global.GlobalConst

INVALID_PAGE, MAX_NAME, MAX_SPACE, MAXATTRNAME, MAXFILENAME, MAXINDEXNAME, MINIBASE_BUFFER_POOL_SIZE, MINIBASE_DB_SIZE, MINIBASE_DEFAULT_SHAREDMEM_SIZE, MINIBASE_MAX_TRANSACTIONS, MINIBASE_MAXARRSIZE, MINIBASE_PAGESIZE, NUMBUF

Fields inherited from interface global.Flags

DEBUG, TEST

Constructor Summary

SortMerge(AttrType[] in1, int len_in1, short[] s1_sizes, AttrType[] in2, int len_in2, short[] s2_sizes, int join_col_in1, int sortFld1Len, int join_col_in2, int sortFld2Len, int amt_of_mem, Iterator am1, Iterator am2, boolean in1_sorted, boolean in2_sorted, TupleOrder order, CondExpr[] outFilter, FldSpec[] proj_list, int n_out_flds)
constructor,initialization

Method Summary

void	close() implement the abstract method close() from super class Iterator to finish cleaning up
Tuple	get_next() The tuple is returned All this function has to do is to get 1 tuple from one of the Iterators (from both initially), use the sorting order to determine which one gets sent up.

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

SortMerge

public SortMerge(AttrType[] in1,
                 int len_in1,
                 short[] s1_sizes,
                 AttrType[] in2,
                 int len_in2,
                 short[] s2_sizes,
                 int join_col_in1,
                 int sortFld1Len,
                 int join_col_in2,
                 int sortFld2Len,
                 int amt_of_mem,
                 Iterator am1,
                 Iterator am2,
                 boolean in1_sorted,
                 boolean in2_sorted,
                 TupleOrder order,
                 CondExpr[] outFilter,
                 FldSpec[] proj_list,
                 int n_out_flds)
          throws JoinNewFailed,
                 JoinLowMemory,
                 SortException,
                 TupleUtilsException,
                 java.io.IOException

constructor,initialization

Parameters:

len_in1 - # of columns in R

s1_sizes - shows the length of the string fields in R.

len_in2 - # of columns in S

s2_sizes - shows the length of the string fields in S

sortFld1Len - the length of sorted field in R

sortFld2Len - the length of sorted field in S

join_col_in1 - The col of R to be joined with S

join_col_in2 - the col of S to be joined with R

amt_of_mem - IN PAGES

am1 - access method for left input to join

am2 - access method for right input to join

in1_sorted - is am1 sorted?

in2_sorted - is am2 sorted?

order - the order of the tuple: assending or desecnding?

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

n_out_flds - number of outer relation fileds

Throws:

JoinNewFailed - allocate failed

JoinLowMemory - memory not enough

SortException - exception from sorting

TupleUtilsException - exception from using tuple utils

java.io.IOException - some I/O fault

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

This provides the next joined tuple.

If there are no remaining joined tuples, null is returned.

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