Add hybrid text plus vector memory search

migrations/V2__hybrid_search.sql

@@ -0,0 +1,36 @@
+ALTER TABLE memories
+    ADD COLUMN IF NOT EXISTS tsv tsvector;
+
+CREATE OR REPLACE FUNCTION memories_tsv_trigger()
+RETURNS trigger
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    NEW.tsv :=
+        setweight(to_tsvector('pg_catalog.english', COALESCE(NEW.content, '')), 'A') ||
+        setweight(
+            to_tsvector('pg_catalog.english', COALESCE(array_to_string(NEW.keywords, ' '), '')),
+            'B'
+        );
+    RETURN NEW;
+END;
+$$;
+
+UPDATE memories
+SET tsv =
+    setweight(to_tsvector('pg_catalog.english', COALESCE(content, '')), 'A') ||
+    setweight(
+        to_tsvector('pg_catalog.english', COALESCE(array_to_string(keywords, ' '), '')),
+        'B'
+    )
+WHERE tsv IS NULL;
+
+DROP TRIGGER IF EXISTS memories_tsv_update ON memories;
+
+CREATE TRIGGER memories_tsv_update
+BEFORE INSERT OR UPDATE OF content, keywords ON memories
+FOR EACH ROW
+EXECUTE FUNCTION memories_tsv_trigger();
+
+CREATE INDEX IF NOT EXISTS idx_memories_tsv
+    ON memories USING GIN (tsv);