demo_explore_index.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Loading faiss with AVX2 support.\n"
     ]
    }
   ],
   "source": [
    "import faiss"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "fname = '....'\n",
    "idx = faiss.read_index(fname)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Explore a loaded index"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.IndexPreTransform; proxy of <Swig Object of type 'faiss::IndexPreTransform *' at 0x7fc0c46a7ea0> >"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "idx"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "So it's an `IndexPreTransform` that wraps another index. To see what's inside, use `downcast_index`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.IndexIVFScalarQuantizer; proxy of <Swig Object of type 'faiss::IndexIVFScalarQuantizer *' at 0x7fc0bc08c3c0> >"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(idx.index)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "An IVFScalarQuantizer. How many centroids? Is it trained? What does the quantizer look like?  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1048576"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(idx.index).nlist"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(idx.index).is_trained"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.Index; proxy of <Swig Object of type 'faiss::Index *' at 0x7fc0bc08c2d0> >"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(idx.index).quantizer"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Obviously it's an index. But what type of index? "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.IndexFlat; proxy of <Swig Object of type 'faiss::IndexFlat *' at 0x7fc0bc11eb10> >"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(faiss.downcast_index(idx.index).quantizer)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Moving to GPU"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "co = faiss.GpuMultipleClonerOptions()\n",
    "co.shard = True\n",
    "idx_gpu = faiss.index_cpu_to_all_gpus(idx, co)\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.IndexPreTransform; proxy of <Swig Object of type 'faiss::IndexPreTransform *' at 0x7fc0bc0921e0> >"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "idx_gpu"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Again behind a PreTransform (on CPU). Let's see what's inside that."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.IndexShards; proxy of <Swig Object of type 'faiss::IndexShardsTemplate< faiss::Index > *' at 0x7fc0bc08c540> >"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(idx_gpu.index)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here are the shards. What does each shard contain? "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.Index; proxy of <Swig Object of type 'faiss::Index *' at 0x7fc0bc0920c0> >"
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(idx_gpu.index).at(0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Let's downcast once more  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<faiss.swigfaiss_avx2.GpuIndexIVFScalarQuantizer; proxy of <Swig Object of type 'faiss::gpu::GpuIndexIVFScalarQuantizer *' at 0x7fc041d9dab0> >"
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(faiss.downcast_index(idx_gpu.index).at(0))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "So here is the GPU Scalar Quantizer. How many inverted lists? "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "1048576"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "faiss.downcast_index(faiss.downcast_index(idx_gpu.index).at(0)).nlist"
   ]
  }
 ],
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