Indexes: Why Some Queries Are Fast and Others Slow
If your application suddenly feels sluggish when listing records or searching, the cause is often a missing index. An index is to a database what the index at the back of a book is to a reader: a shortcut to the right page.
This article explains what indexes do, why they are not free, and why we add them carefully rather than to every column.
How an Index Helps
Without an index, the database may have to read every row to find what you asked for — fine with a thousand rows, painful with ten million. An index lets it jump straight to the matching rows instead.
Why Not Index Everything
- Indexes take up storage space.
- Every insert or update must also update the indexes, slowing writes.
- Too many unused indexes waste resources and confuse the query planner.
How We Decide
We look at the queries your application actually runs, identify which columns are used to filter and sort, and index those. We also review slow query logs after launch to catch anything that needs tuning under real load.
Frequently Asked Questions
Can adding an index break anything?
No — indexes do not change your data or results, only the speed of finding it. The main cost is a slight slowdown on writes.
If you need a hand with any of this, your Progressive Robot delivery team is ready to help. Raise a ticket from the Support area of your client portal or speak to your account manager and we will guide you through the next steps.