Show HN: How This Graybeard Built the Fastest and Freest Postgres BM25 Search

Re:Show HN: How This Graybeard Built the Fastest and Freest ... by mbreese on Tuesday March 31, 2026 @05:14PM (#47593548)

While we’re talking about filtering — is there a way to set a WHERE clause when you’re setting up the index? I’ve been working on this a lot recently for a hybrid vector search in pg. One of the things that I’m running up against is setting a good BM25 index for a subset of a table (the where clause). I have a document subsets with very different word frequencies, so I’m trying to make sure that the search works on a set subset.

I think I can also setup partitions for this, but while you’re here… I’m very excited to start to roll this out.

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Re:Show HN: How This Graybeard Built the Fastest and Freest ... by tjgreen on Tuesday March 31, 2026 @05:24PM (#47593650)

Partitions would be one option, and we've got pretty robust partitioned table support in the extension. (Timescaledb uses partitioning for hypertables, so we had to front-load that support). Expression indexes would be another option, not yet done but there is a community PR in flight: https://github.com/timescale/pg_textsearch/pull/154

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