How to correctly compare a large amount of information?

Question

C++ / C#

Good afternoon, there are three sources of information on the object (information is taken from excel, so I’ll call the source LIST )

1SHEETS (external source):
Object ID
Date of object creation
Time to create the object

2SHEETS:
Type of object Object
ID
Date of object creation (may differ from the external source +-2min )
Time to create an object

3SHEETS:
Object type Object
ID
Date of object creation

The process should be short, about 15-20 minutes, hence the problem, how to implement it correctly?
It is required to match objects and mark them like this:
Object found
Object not found The object
has a different time to create the

object

Answer 1

Just 50k lines? So it will definitely fit into the RAM. If it fits into RAM, then you can create a Dictionary simply, well, take values ​​by key. If your computer does not allow processing such volumes, you can use any keyvalue database on a remote computer or in the cloud (this is a joke)