56 lines
1.9 KiB
Python
56 lines
1.9 KiB
Python
# Copyright (c) Facebook, Inc. and its affiliates.
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#
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# This source code is licensed under the MIT license found in the
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# LICENSE file in the root directory of this source tree.
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from typing import List
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import faiss
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import logging
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LOG = logging.getLogger(__name__)
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def merge_ondisk(trained_index: faiss.Index,
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shard_fnames: List[str],
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ivfdata_fname: str) -> None:
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""" Add the contents of the indexes stored in shard_fnames into the index
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trained_index. The on-disk data is stored in ivfdata_fname """
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# merge the images into an on-disk index
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# first load the inverted lists
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ivfs = []
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for fname in shard_fnames:
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# the IO_FLAG_MMAP is to avoid actually loading the data thus
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# the total size of the inverted lists can exceed the
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# available RAM
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LOG.info("read " + fname)
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index = faiss.read_index(fname, faiss.IO_FLAG_MMAP)
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index_ivf = faiss.extract_index_ivf(index)
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ivfs.append(index_ivf.invlists)
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# avoid that the invlists get deallocated with the index
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index_ivf.own_invlists = False
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# construct the output index
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index = trained_index
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index_ivf = faiss.extract_index_ivf(index)
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assert index.ntotal == 0, "works only on empty index"
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# prepare the output inverted lists. They will be written
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# to merged_index.ivfdata
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invlists = faiss.OnDiskInvertedLists(
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index_ivf.nlist, index_ivf.code_size,
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ivfdata_fname)
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# merge all the inverted lists
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ivf_vector = faiss.InvertedListsPtrVector()
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for ivf in ivfs:
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ivf_vector.push_back(ivf)
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LOG.info("merge %d inverted lists " % ivf_vector.size())
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ntotal = invlists.merge_from(ivf_vector.data(), ivf_vector.size())
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# now replace the inverted lists in the output index
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index.ntotal = index_ivf.ntotal = ntotal
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index_ivf.replace_invlists(invlists, True)
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invlists.this.disown()
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