LESSON 3.3
Tuning a slow query
Learn key techniques and workflows in PostgreSQL for Developers.
8m
intermediate
6,975 students
Overview
Rewriting is often better than indexing. Remove the function on the indexed column, cut the rows early, and check the plan again.
In this lesson you will:
- Rewrite predicates so an index can be used
- Reduce the row count as early as possible
- Verify the improvement with a fresh plan
Pro Tip
Wrapping an indexed column in a function usually disables the index. Transform the parameter instead.