Algorithms: Merge Join
From wikinotes
Merge joins require that both tables are sorted by the column with the join condition.
This is ideal for indexed columns, since most indexes work by sorting entries.
Documentation
merge joins https://www.youtube.com/watch?v=iBhnVjrudbQ
Table1/2 are iterated through at the same time.
Every time the pkey from table-1 doesn't match table-2,
the next table1 entry is chosen.
It is very efficient.
