OpenAI replaced text-embedding-ada-002 with text-embedding-3-small (1536d, cheap) and text-embedding-3-large (3072d, top quality), both Matryoshka-truncatable via the dimensions API parameter.
Think of OpenAI's lineup of text to fingerprint services like a coffee shop menu. The old standard was one fixed-size cup called ada-002. The new menu offers two cups: a smaller one called 3-small that costs less and tastes nearly as good for most customers, and a larger one called 3-large for those who want the premium version. Both new cups also offer something the old cup never did: you can ask the barista for a half-pour at the counter, paying only for what fits in your cup, instead of always getting the full pour. The old cup is still on the menu for loyal customers, but the staff quietly steer newcomers toward the new pair.
Detailed answer & concept explanation~6 min readEverything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example.
Everything important, quickly.
5 minutes: the two replacements, the pricing shift, Matryoshka, and how to migrate without breaking the index.
| Model | Dimensions | Price per 1M tokens | MTEB lift over ada-002 | Matryoshka |
|---|---|---|---|---|
| text-embedding-ada-002 | 1536 (fixed) | $0.10 (deprecated default) | baseline | no |
| text-embedding-3-small | 1536 (truncatable) | $0.02 | +5 points typical | yes |
| text-embedding-3-large | 3072 (truncatable) | $0.13 | +8 to +10 points typical | yes |
Real products, models, and research that use this idea.
- OpenAI announcement of the text-embedding-3 family in January 2024, including the dimensions parameter that exposes Matryoshka truncation.
- Pinecone migration guides describe parallel-index patterns specifically for ada-002 to text-embedding-3-large cutovers.
- LangChain and LlamaIndex defaulted their OpenAI embedder examples to text-embedding-3-small after the release.
- Many RAG products kept ada-002 in production for six to twelve months post-release, illustrating that deprecation is a planning exercise, not an emergency.
What an interviewer would ask next. Try answering before peeking at the approach.
QHow would you decide between text-embedding-3-small at 1536 dim and text-embedding-3-large truncated to 1536 dim?
QWalk through a zero-downtime migration from ada-002 to text-embedding-3-large.
Don't say thisRed flags and common mistakes that signal junior thinking. Click to expand.
Red flags and common mistakes that signal junior thinking. Click to expand.
Still defaulting to ada-002 in new builds because the docs you read in 2023 said so, missing roughly 50% cost savings and a 5 to 10 point MTEB lift.
The night-before-the-interview bullets. Scan these on the way to the call.
Primary sources. Skim if you want the original framing.
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