Hybrid search: keywords plus vectors
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
combine full-text and vector search and say when each wins.
Planned topics
- Vectors win on meaning and paraphrase ("my package is late").
- Keywords win on exact terms: order numbers, SKUs, error codes, names.
- Hybrid: run both, then merge the rankings. Reciprocal Rank Fusion (RRF) merges by rank, so scores need no common scale.
- PostgreSQL does both:
tsvectorwith a GIN index plus pgvector. - Test with real questions; do not assume hybrid is always better.
Draft outline details
Demonstration
two ranked lists merged: RRF score = sum of 1 / (k + rank) per list (k = 60 is a common constant). An article ranked 1st in text and 3rd in vector beats one ranked 1st in only one list.
Check your understanding
Which search finds the order id "ORD-88231"?
Show answer
Keyword search; vectors do not match exact codes reliably.
Practice
Apply this lesson with the module's lab, exercises and quiz.
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