Is it possible to write metadata into index files?

[xz328]

Summary

Hi,

I am trying to write metadata, e.g., the date, the user, the faiss version, and other dependencies into index files. Is there a way to achieve this?

[mdouze]

You can prepend or append it to the index data. index_read will just sequentially read the index data and leave the read pointer where at the beginning of the remaining data. See

https://github.com/facebookresearch/faiss/blob/main/faiss/index_io.h#L39

[xz328]

Thanks. Could you explain more about how I can prepend or append the metadata to the index data, i.e., using what method?

The mentioned line of the code (https://github.com/facebookresearch/faiss/blob/main/faiss/index_io.h#L39) seems to explain that the write_index method takes two arguments, one the index object and the other file name. I don't quite get how that relates to my question, as I am not a C programmer. Could you explain further if I have misunderstood it?

Thanks

[MrCabss69]

LangChain's integration keeps the metadata in a separate structure that maps to the index items. Instead of trying to write the metadata inside the FAISS index file, you can store it in a separate file/database and maintain the relationship between the two using identifiers.

Source Code