bqredis 0.0.2

A Redis-backed cache for BigQuery

bqredis

This library provides functionality to cache calls to bigquery with redis.

The use case which drove creation of this library was a web-based dashboard which pulled data from bigquery. Often queries were inexplicably slow. Even worse, a slow loading page would prompt users to refresh, would would saturate the available threadpools, further slowing the experience.

This is the result: a library which uses redis to cache bigquery results and prevents more than one inflight request from going out from a given cache instance at a time. Enough talking, let's cut to an example:

import bqredis

_QUERY = "SELECT * FROM `bigquery-public-data.country_codes.country_codes` ORDER BY alpha_3_code DESC LIMIT 10"

redis_client = redis.Redis.from_url("redis://localhost:6379")
cache = bqredis.BQRedis(redis_client, redis_cache_ttl_sec=300, redis_background_refresh_ttl_sec=5)
# Subsequent calls to this for the next 300 seconds will be cached.
cache.query_sync(_QUERY)
# Start a background refresh for this query.
promise = cache.submit_background_refresh(_QUERY)
promise.result()
# More calls for refreshing the background cache for the next 5 seconds will
# not start.

Return type

By default, this library will parse results as a pyarrow.RecordBatch. To instead use a different format, override the convert_arrow_to_output method. For example, to have results as a polars.DataFrame do the following:

import polars
import pyarrow

class BQRedisPolars(bqredis.BQRedis):
    def convert_arrow_to_output_format(self, records: pyarrow.RecordBatch) -> polars.DataFrame:
        return polars.from_arrow(records)

pl_cache = BQRedisPolars(redis_client, redis_cache_ttl_sec=300, redis_background_refresh_ttl_sec=5)
pl_cache.query_sync(_QUERY)

We use arrow as the underlying format because it is the direct format being sent by BigQuery. This can be converted with 0-copy to polars as show above.