For what reasons is it impossible to support such a large number of connections to the database simultaneously?

It is impossible to support a very large number of database connections simultaneously for several reasons:

• Database server limitations: DBMS usually has a limit on the number of concurrent connections to prevent overload.

• Server resources: Each connection consumes memory and CPU time. With a large number of connections, the server may exhaust its resources.

• Network restrictions: Limitations at the operating system and network level (e.g., maximum number of open sockets).

• Transaction and lock management: Multiple concurrent connections increase the likelihood of conflicts and locks.

• Performance loss: A large number of connections reduces overall performance due to context switching and resource contention.

To address this, connection pools are typically used, which limit the number of active connections and reuse them:

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

engine = create_engine('postgresql://user:pass@host/db', pool_size=20, max_overflow=0)
Session = sessionmaker(bind=engine)

# Now, no more than 20 active connections at the same time

Thus, maintaining an enormous number of simultaneous connections directly is inefficient and technically limited.