How to return rows listed in descending order of COUNT(*)?

Question

I have a table called foo with these fields:

- id

- type

- parentId

I want to select a list of parent IDS, in the descending

Answer 1

How can this be done in the most efficient way and putting the least load on the server?

The key is the the most efficient way.

Not a Count() for sure, but most efficient is... to read a field, which you are storing the Count result. You can update it with a trigger or after insert.

Especially when

There can be thousands-hundreds of thousands of records in the table