Suppose that we have 2 huge tables,
Table A has 3 columns, it looks like:
city, region, zipcode
California City, California, 10000
New York City, New York, 10010
Phoenix, Arizona,
...
The zipcodes are sometimes empty.

Table B also has the 3 columns, but the city and region text are noisy
for example:
city, region, zipcode
nyc, new york, 10010,
Phoenix, AR, 10003
...

So the question is how should we use Table B to fill the missing zipcodes in Table A assuming that the size of these 2 tables are very big?