Prepared SQL query time vs regular query time

Question

I know, from whatever I've read, prepared statements are faster since pre-compiled cached version is used for recurring queries. My doubt is : Exactly where time is saved? I see, only the time taken in preparing a query could be saved. Even prepared statements have to do database search and so no time is saved there. Am I wrong?

Answer 1

That's correct. The time saved by using prepared statements is generally in the database engine planning/compiling the query.

Answer 2

The part of a "prepared query" that is prepared is the execution plan. The plan tells the database how to execute the query; which indexes to use, in which order. The execution plan also resolves any access rights.

Time is saved by building the execution plan once instead of for every query.