From 3c09df83f67c6f9f1286a4ac49d78a32eba084a7 Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Sun, 31 Mar 2024 22:52:51 -0700
Subject: [PATCH] Updated readme [skip ci]

---
 README.md | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/README.md b/README.md
index 37077ce..348cf3e 100644
--- a/README.md
+++ b/README.md
@@ -400,6 +400,29 @@ Use [partitioning](https://www.postgresql.org/docs/current/ddl-partitioning.html
 CREATE TABLE items (embedding vector(3), category_id int) PARTITION BY LIST(category_id);
 ```
 
+## Types
+
+- `vector`
+- `halfvec`
+
+## Half-Precision
+
+```sql
+CREATE TABLE items (id bigserial PRIMARY KEY, embedding halfvec(3));
+INSERT INTO items (embedding) VALUES ('[1,2,3]'), ('[4,5,6]');
+CREATE INDEX ON items USING hnsw ((embedding::halfvec(3)) halfvec_l2_ops);
+```
+
+```sql
+SELECT id FROM items ORDER BY embedding::halfvec(3) <-> '[1,2,3]' LIMIT 5;
+```
+
+```sql
+SELECT id FROM (
+    SELECT * FROM items ORDER BY embedding::halfvec(3) <-> '[1,2,3]' LIMIT 20
+) ORDER BY embedding <-> '[1,2,3]' LIMIT 5;
+```
+
 ## Hybrid Search
 
 Use together with Postgres [full-text search](https://www.postgresql.org/docs/current/textsearch-intro.html) for hybrid search.