PostgreSQL LIKE query performance variations

Question

I have been seeing quite a large variation in response times regarding LIKE queries to a particular table in my database. Sometimes I will get results within 20

Answer 1

for what it's worth, Django ORM tends to use UPPER(text) for all LIKE queries to make it case insensitive,

Adding an index on UPPER(column::text) has greatly sped up my system, unlike any other thing.

As far as leading %, yes that will not use an index. See this blog for a great explanation:

https://use-the-index-luke.com/sql/where-clause/searching-for-ranges/like-performance-tuning