The Real Cost of Indexes
Indexing isn't free. Let's look at what we actually pay for faster reads.
By Sujith M.S.·Sep 10, 2026·8 min read
DatabasesSystemsPerformance
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The Real Cost of Indexes
The Real Cost of Indexes
We all say:
"The query is slow? Just index it."
But indexing isn't free.
You're trading one cost for another.
1. Storage
An index is a separate data structure sitting next to your table.
More indexes means more disk space.
For example:
SELECT pg_size_pretty(
pg_relation_size('users')
);
SELECT pg_size_pretty(
pg_relation_size('idx_users_email')
);