Hacker News Reader

Silly question, I'm using pg right now and most of my queries are something like this (in english)

Find me some results in my area that contain these categoryIds and are slotted to start between now and next 10 days.

Since its already quite a filtered set of data, would that mean I should have little issues adding pg text search because with correct indexing and all, it will usually be applied to a small set of data?

Thanks

View on HN

I'm not a DBA, so I can't say for certain simply due to a gap in my knowledge. But in my experience, it depends on a lot of factors. Sometimes pg will use an index before performing the search ops, other times a subquery is needed. Check out pgmustard and dig into your slow query plans. :)

You might be just fine adding an unindexed tsvector column, since you've already filtered down the results.

The GIN indexes for FTS don't really work in conjunction with other indices, which is why https://github.com/postgrespro/rum exists. Luckily, it sounds like you can use your existing indices to filter and let postgres scan for matches on the tsvector. The GIN tsvector indices are quite expensive to build, so don't add one if postgres can't make use of it!

Great read on the pitfalls of GIN indexes: https://iamsafts.com/posts/postgres-gin-performance/ (I'm not the author, but this did happen to me.)

Reply on news.ycombinator.com