How to disable/enable different query optimizations in POSTGRESQL?

Question

I'm doing some test to see the capability of Postgresql query performance. And my plan is to disable/enable different query optimizations, such as disable (automatic) index, disable re-order joins etc. is there some configuration to achieve this quickly or what part source code should I revise? thanks.

Answer 1

PostgreSQL provides debug parameters for exactly this.

See the enable_ params in the docs.

Please don't use them in production; it might seem like a good idea at the time, but those settings won't adapt as the data changes and grows, so what starts out as a performance win will probably become a problem later.