updating main sheet

I have a very large dataset with about 200.000 rows of information (in 6 columns). The idea is to regularly update this sheet with information from other sheets (usually 100.000 rows). Both sheets have a unique identifier.
What's the best way to do this? If I loop through all the rows it will take forever.

Basic explanation of my data:
Main sheet:
Column A = unique identifier (street & zipcode)
Column B = price
Column C = ....
Column D = date

Other sheets:
Column A = unique identifier (street & zipcode)
Column B = price
Column C = ....
column D= date

If a record from other sheets is allready in main sheet then I just want to add a extra column in the main sheet sheet with date from column D.

Any ideas?