# What is index overhead on writes?

DevFeed: [What is index overhead on writes?](<https://devfeed.tech/articles/what-is-index-overhead-on-writes-33673.md>)

Original publisher: [Read original article](<https://www.depesz.com/2026/01/06/what-is-index-overhead-on-writes/>)

Author: depesz

Published: 2026-01-06T11:57:10Z

Content type: article

Language: en

Sources: [select \* from depesz;](<https://devfeed.tech/sources/select-from-depesz.md>)

Topics: [data](<https://devfeed.tech/topics/data.md>)

Tags: [benchmark](<https://devfeed.tech/tags/benchmark.md>), [btree](<https://devfeed.tech/tags/btree.md>), [delete](<https://devfeed.tech/tags/delete.md>), [gin](<https://devfeed.tech/tags/gin.md>), [index](<https://devfeed.tech/tags/index.md>), [insert](<https://devfeed.tech/tags/insert.md>), [operations](<https://devfeed.tech/tags/operations.md>), [overhead](<https://devfeed.tech/tags/overhead.md>), [performance](<https://devfeed.tech/tags/performance.md>), [postgresql](<https://devfeed.tech/tags/postgresql.md>), [speed](<https://devfeed.tech/tags/speed.md>), [tutorial](<https://devfeed.tech/tags/tutorial.md>), [uncategorized](<https://devfeed.tech/tags/uncategorized.md>), [update](<https://devfeed.tech/tags/update.md>)

## AI overview

The article measures how indexes affect write performance using PostgreSQL 18 and a one-million-row test table. It reports that loading performance decreases as indexes are added, and that a roughly 3.6-fold increase in storage corresponded to an eightfold slowdown in the tested case. A single wide index performed better than ten separate indexes, though the author notes that the configurations solve different computational problems.

## Source excerpt

One of things people learn is that adding indexes isn't free. All write operations (insert, update, delete) will be slower - well, they have to update index. But realistically - how much slower? Full tests should involve lots of operations, on realistic data, but I just wanted to see some basic info. So I figured ... Continue reading "What is index overhead on writes?"