‫So now let's talk about a second type
‫of database you will see on AWS,
‫which is Amazon ElastiCache.
‫So the same way you use RDS to get
‫managed Relational Databases,
‫you're going to get ElastiCache to get a managed,
‫Redis or Memcached database.
‫These caches are going to be in-memory databases
‫with high performance, low latency.
‫So anytime in the exam you see something that says
‫you need an in-memory database,
‫you have to think directly ElastiCache.
‫Now ElastiCache will be helpful
‫to reduce load off of databases
‫that have a read intensive workloads.
‫The idea is that if we have an RDS database
‫and we're doing a lot of query on it
‫and they're the same queries all the time,
‫we put a bit of pressure onto that RDS database.
‫Instead what we could be doing,
‫is to use a cache to reduce the pressure
‫off of the database by making sure the queries
‫are directly going onto my in-memory database
‫through ElastiCache.
‫And because this is a managed database,
‫then AWS will take care of all the operating system
‫maintenance and patching, the optimizations,
‫the setup, the configuration, the monitoring,
‫failure recovery and backups.
‫So we've already learned a lot about caches in this exam
‫but we need to know it's an in-memory database
‫and the solution architecture around using a cache
‫looks like this.
‫So you're Elastic Load Balancer
‫will go to your EC2 Instances.
‫Possibly in an ASG.
‫They will be reading and writing data from
‫your Amazon RDS database, which is slow.
‫And then if possible there will be caching some values
‫into an Amazon ElastiCache database
‫and this will be very fast because it's in-memory.
‫And so with ElastiCache, there will be pressure
‫taken off the main RDS database
‫and put it on to the ElastiCache database
‫and that's the whole idea behind the cache.
‫You want to save the queries somewhere else,
‫so that they're very readily available.
‫Easily accessible and they can relieve, again pressure
‫from the main database.
‫So that's it, that's all you need to know going
‫into the exam and I will see you in the next lecture.