Encrypting and Decrypting Database

Question

I have an encrypted database with columns bookname, author, filename, category.

Now I need to serve the decrypted data to the user, my approach is:

booktitles = libraryfiles.query.all()
dictor = {}
for i in booktitles:
  dictor[f"{rsa.decrypt(i.bookname, privateKey).decode()}"] = [rsa.decrypt(i.category, privateKey).decode(),rsa.decrypt(i.filename, privateKey).decode(),rsa.decrypt(i.author, privateKey).decode()]

Recreating the whole database as a dictionary.

Now I have a search functionality which takes "booktitle" and "category"

I filter through the dictionary by:

filtered_dict = {k:v for (k,v) in dictor.items() if request.form['search'] in k and request.form['category'] in v}
    

Now I'm concerned with the efficiency of this approach as:

1. I need to for loop through the entire database while performing a decryption on each value

2. I need to for loop through the dictionary

3. Instead of querying into the database I'm going to query on the dictionary

Does this kind of approach would cause a massive delay? Or is it the same as querying into a database?