title_wip

Row 7:
──────
title:                Skylab
text:                 Skylab was a space station launched and operated by NASA and was the United States' first space station. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a weight of 169,950 pounds (77 t).  Three manned missions to the station, conducted between 1973 and 1974 using the Apollo Command/Service Module (CSM) atop the smaller Saturn IB, each delivered a three-astronaut crew.
num_concepts_matched: 4
min_distance:         0.99155205
avg_distance:         1.0769911855459213

Row 8:
──────
title:                Orbital spaceflight
text:                 An orbital spaceflight (or orbital flight) is a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit. To do this around the Earth, it must be on a free trajectory which has an altitude at perigee (altitude at closest approach) above 100 kilometers (62 mi) (this is, by at least one convention, the boundary of space).  To remain in orbit at this altitude requires an orbital speed of ~7.8 km/s.
num_concepts_matched: 4
min_distance:         1.0075209
avg_distance:         1.085978478193283

Row 9:
───────
title:                Dragon (spacecraft)
text:                 Dragon is a partially reusable spacecraft developed by SpaceX, an American private space transportation company based in Hawthorne, California. Dragon is launched into space by the SpaceX Falcon 9 two-stage-to-orbit launch vehicle, and SpaceX is developing a crewed version called the Dragon V2.During its maiden flight in December 2010, Dragon became the first commercially built and operated spacecraft to be recovered successfully from orbit.
num_concepts_matched: 4
min_distance:         1.0222818
avg_distance:         1.0942841172218323

Row 10:
───────
title:                Space capsule
text:                 A space capsule is an often manned spacecraft which has a simple shape for the main section, without any wings or other features to create lift during atmospheric reentry.Capsules have been used in most of the manned space programs to date, including the world's first manned spacecraft Vostok and Mercury, as well as in later Soviet Voskhod, Soyuz, Zond/L1, L3, TKS, US Gemini, Apollo Command Module, Chinese Shenzhou and US, Russian and Indian manned spacecraft currently being developed.
num_concepts_matched: 4
min_distance:         1.0262821
avg_distance:         1.0882147550582886
```

**Performance:** 10 rows in set. Elapsed: 1.157 sec. Processed 10.00 million rows, 32.76 GB (8.64 million rows/s., 28.32 GB/s.) Peak memory usage: **6.05 GiB**.

### Key Insight[​](#key-insight "Direct link to Key Insight")

The results? Not just good. Surprisingly good. It's not obvious that floating points stripped of their entire mantissa and half their exponent still hold meaningful information.

**The key insight behind QBit is that vector search still works if we ignore insignificant bits.**

Memory usage reduced from **6.05 GB to 740 MB** while maintaining excellent semantic search quality!

## Conclusion[​](#result "Direct link to Conclusion")

QBit is a column type that stores floats as bit planes.
It lets you choose how many bits to read during vector search, tuning recall and performance without changing the data.
Each vector search method has its own parameters that decide trade-offs for recall, accuracy, and performance.
Normally, these have to be chosen up-front.
If you get them wrong, a lot of time and resources are wasted, and changing direction later becomes painful.
With QBit, no early decisions are needed.
You can adjust precision and speed trade-off directly at query time, exploring the right balance as you go.

---

*Adapted from the [blog post](https://clickhouse.com/blog/qbit-vector-search) by Raufs Dunamalijevs, published October 28, 2025*

- [Vector search primer](#vector-search-primer)
  - [Understanding embeddings](#understanding-embeddings)- [Approximate Nearest Neighbours (ANN)](#approximate-nearest-neighbours)
    - [Quantisation](#quantisation)- [Hierarchical Navigable Small World (HNSW)](#hnsw)- [Comparison of approaches](#comparison-approaches)- [QBit deep dive](#qbit-deepdive)
      - [Quantised Bit (QBit)](#quantised-bit)- [The data type](#the-data-type)- [The distance calculation](#the-distance-calculation)- [I/O Optimisation](#io-optimisation)- [Calculation optimisation](#calculation-optimisation)- [Example with DBpedia](#example)
        - [Setup](#setup)- [Search query](#search-query)- [Key Insight](#key-insight)- [Conclusion](#result)

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