That's actually more than one question because the answer is different.
To use redis as the cache, you can use our port on github: https://github.com/md-systems/redis
The README isn't been fully updated yet but the quickstart part tells you how to configure it (after enabling the module):
$settings['redis.connection']['interface'] = 'PhpRedis'; // Can be "Predis".
$settings['redis.connection']['host'] = '1.2.3.4'; // Your Redis instance hostname.
$settings['cache']['default'] = 'cache.backend.redis';
To use redis for the cache tags checksum service, which most cache backends use, you need to override a service, for example in sites/default/services.yml, add the following:
To use the redis cache tag checksum implementation, put this in
sites/default/services.yml or any other yml file that is loaded after
core.services.yml:
services:
cache_tags.invalidator.checksum:
class: Drupal\redis\Cache\RedisCacheTagsChecksum
arguments: ['@redis.factory']
tags:
- { name: cache_tags_invalidator }
In the same way, you can replace any service that is defined in the core or one of the module services.yml files with a different implementation, for example some of the mongodb service implementations provided by https://www.drupal.org/project/mongodb.
In general, you don't think in terms of tables but services and API's, and you either replace them directly or by configuration he factory service (cache/key value/queue/...)
