Python: Introducing the Faiss Connector

[eavanvalkenburg]

Motivation and Context

This PR adds a FaissVectorStore and FaissCollection
Faiss is a really fast similarity search engine, which runs in memory.
You can also use GPU's with it, but you will have to build the package yourself.

Description

Closes #4130

TODO:

• other index kinds
• deal with distance functions
• validate GPU setup
• maybe subclass InMemoryCollection
• tests

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
semantic_kernel/connectors/memory
faiss.py	119	7	94%	91, 99, 103, 131–132, 159, 217
semantic_kernel/connectors/memory/in_memory
in_memory_collection.py	139	15	89%	70, 122, 124, 144, 183, 198, 210, 228–231, 235, 237, 239–240
TOTAL	19762	2584	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3226	5 💤	0 ❌	0 🔥	1m 42s ⏱️

[Copilot]

PR Overview

This PR introduces a new Faiss connector for semantic-kernel, including implementations for FaissCollection and FaissStore along with comprehensive unit tests and sample usage updates.

• Adds FaissCollection and FaissStore classes to integrate Faiss as an in-memory similarity search engine.
• Updates tests, configuration (pyproject.toml), and sample usage to support the new Faiss connector.

Reviewed Changes

File	Description
python/tests/unit/connectors/memory/faiss/test_faiss.py	Adds unit tests for Faiss functionality.
python/semantic_kernel/connectors/memory/faiss.py	Implements the FaissCollection and FaissStore classes.
python/tests/conftest.py	Updates import for Kernel initialization.
python/pyproject.toml	Adds dependency for faiss-cpu.
python/samples/concepts/memory/complex_memory.py	Integrates FaissCollection into sample usage.
python/semantic_kernel/connectors/memory/in_memory/in_memory_collection.py	Refines generic types for in-memory collections.
python/semantic_kernel/data/vector_storage/vector_store.py	Minor type annotations update.

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.