Add query_namespaces

[jhamon]

Problem

Sometimes people would like to run a query across multiple namespaces

Solution

Run a query for each namespace in parallel, then merge the results using a heap

from pinecone import Pinecone
import random

pc = Pinecone(api_key='api-key')

index = pc.Index(
    host="https://indexhost/",
    pool_threads=10
)

query_vec = [random.random()] * dimension

combined_results = index.query_namespaces(
    vector=query_vec,
    namespaces=["ns1", "ns2", "ns3", "ns4"],
    include_values=False,
    include_metadata=True,
    filter={"publication_date": {"$eq":"Last3Months"}},
    top_k=100
)

TODO

A grpc implementation of this will follow in a separate PR. I have WIP on it, but some mypy type issues were causing me headaches and I'd rather land this stuff first.

Type of Change

• New feature (non-breaking change which adds functionality)

Test Plan

Added integration tests

[rohanshah18]

Nice work! Started an internal discussion. LGTM!

[austin-denoble]

Overall this felt easier to review than I thought it would be, nice job organizing things around these specific classes, and how things are handled by the query_namespaces function itself.

I left a comment about the code added to the generated core.

[austin-denoble]

Is this just manually stubbing out retries in the generated code for now? Just curious, also regarding the print statement down there and whether it should be uncommented.

[jhamon]

This was just me throwing in something basic to get started. This is used to wrap __call_api, but I need to investigate the tuning of the constants and stuff to get the sleep intervals to sensible levels.

Also re: this being generated code, very soon I will be moving these elsewhere and not generating them, since the ApiClient and a couple other classes don't contain any generated content.