How to calculate a mean vector out of a batch of vectors in OpenSearch / Elasticsearch?

I have 1 billion documents.

Each document has a field with a vector named `embedding`.

Each embedding has 768 dimensions.

I want to find the mean vector out of this batch of documents.

A mean vector is, for example:

Assume I have 3 documents.

1 embedding for each document -> 3 embeddings: \[1, 2\] \[3, 4\] \[5, 6\]

The mean vector of this bucket of documents will be \[(1+3+5)/3, (2+4+6)/3\] -> \[3, 4\]

**What's the most time-efficient way I can …

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