Hacker News new | ask | show | jobs
by branko_d 908 days ago
> And if you ever need to read anything even once database without indexes is slow

This may be true in most cases, but not all. It just depends on your access pattern. If all you do are full table scans (possibly feeding to hash-joins), you won't benefit from indexes at all!

The whole point is that indexes do not auto-magically improve performance with no downsides. If they did, we could just index all columns and call it a day!

1 comments

> If all you do are full table scans (possibly feeding to hash-joins), you won't benefit from indexes at all!

In most cases it means that you shouldn't be doing what youa re trying to do. Or best case, that maybe database is not the right tool for your job.

True, but it's still relevant in the early stages of iterating on a project. I'm familiar with one team that started investing in database-level optimization months before even beginning to deprecate their `loadAllRowsFromTheLargestTable` RPC.