MongoDB Atlas: create a Vector Search index that actually works
Shows how to fix mongoDB Atlas: create a Vector Search index that actually works. Use it when you hit this exact problem. Skip it when your error message or symptom looks different.
TL;DR
Use mongosh, a driver, or the Atlas UI (Search tab, JSON editor). The definition shape: `js db.docs.createSearchIndex("vec\_idx", "vectorSearch", { fields: [ { type: "vector", path: "embedding", numDimensions: 1536, similarity: "cosine" }, { type: "filter", path: "tenantId" } ] });
Steps
- Use mongosh, a driver, or the Atlas UI (Search tab, JSON editor). The definition shape:
db.docs.createSearchIndex("vec_idx", "vectorSearch", {
fields: [
{ type: "vector", path: "embedding", numDimensions: 1536, similarity: "cosine" },
{ type: "filter", path: "tenantId" }
]
});When to use
You are seeing this: The definition shape: `js db.docs.createSearchIndex("vec\_idx", "vectorSearch", { fields: [ { type: "vector", path: "embedding", numDimensions: 1536, similarity: "cosine" }, { type: "filter", path: "tenantId" } ] }); ` Use this skill when you run into "MongoDB Atlas: create a Vector Search index that actually works".
When not to use
If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.
Versions
No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.
Why this happens
The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.
Maintainer review
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