Hash join implemented in Python.

Python_Hash_Join.py

from collections import defaultdict
 
def hashJoin(table1, index1, table2, index2):
    h = defaultdict(list)
    # hash phase
    for s in table1:
        h[s[index1]].append(s)
    # join phase
    return [(s, r) for r in table2 for s in h[r[index2]]]
 
table1 = [(27, "Jonah"),
          (18, "Alan"),
          (28, "Glory"),
          (18, "Popeye"),
          (28, "Alan")]
table2 = [("Jonah", "Whales"),
          ("Jonah", "Spiders"),
          ("Alan", "Ghosts"),
          ("Alan", "Zombies"),
          ("Glory", "Buffy")]
 
for row in hashJoin(table1, 1, table2, 0):
    print(row)