Athena is built on a decoupled storage and compute architecture, though it only provides and controls the compute part and does not manage ingestion or storage. It is also only on multi-tenant shared resources. If you are a Redshift customer you can use Redshift Spectrum, which is like dedicated Athena but not built on Presto, deployed on up to 10x the number of Redshift nodes in your own VPC, for the same price as Athena.
Redshift has the oldest architecture with the best options. It does not separate storage and compute. While it now has RA3 nodes which allow you to scale compute and only cache the data you need locally, all compute still operates together. You cannot separate workloads. While you can only run Redshift as an isolated workload on AWS, it has the most options on AWS, including the ability to deploy it in your own VPC.
Athena is a shared multi-tenant resource, which means each account needs to be throttled to protect every other account’s performance. One customer was unable to handle any table or join above 5 billion rows. By default Athena supports a maximum of 20 concurrent users. If scalability is a top priority, Athena is probably the wrong choice.
Redshift is limited in scale because even with RA3, it cannot distribute different workloads across clusters. While it can scale to up to 10 clusters automatically to support query concurrency, it can only handle a maximum of 50 queued queries across all clusters by default. In addition, because it locks at the table level, it is better suited for batch ingestion and limited in its write throughput.
Athena, and Presto, should be the worst at performance, by design. The reason is that it sacrifices storage-compute optimization to get support for federated queries across multiple data sources. But there is a reason Presto is so popular. Even with that handicap, Presto and Athena do very well. Presto can come close to Redshift and Snowflake in performance when both Presto and the external storage is managed by experts. But there is no support for indexing. Specifically with Athena, you cannot guarantee performance as a shared multi-tenant resource. In general, if performance is a top concern and you can bring data together via a data pipeline and optimize data with compute, then Athena or Presto are not the best choice.
Redshift does provide a result cache for accelerating repetitive query workloads and also has more tuning options than some others. But it does not deliver much faster compute performance than other cloud data warehouses in benchmarks. While its storage access is more efficient, with smaller data block sizes being fetched over the network, it does not perform a lot of query optimization, and has no support for indexes. It also has less support for semi-structured data or low-latency ingestion at any reasonable scale.
Athena is one of the best “one-off” query engines; all you have to do is provide the data and pay $5 a TB. If you need to quickly pull together multiple data sources, it’s a great option. Redshift Spectrum is a great add-on option for Redshift for federated queries. But if you don’t need federated queries, need performance, and need anything other than one-off or occasional analytics, Athena is not a good option for any of these use cases. There is no data, network or query optimization, no indexing beyond pruning indexes like others.
Redshift was originally designed to support traditional internal BI reporting and dashboard use cases for analysts. Without second-level performance, it cannot support any interactive and ad hoc analytics. It also has a limit of 50 queued queries by default, which limits concurrency, and a lack of support for continuous ingestion. All of these limitations mean Redshift for operational and customer-facing use cases.
Athena is arguably the easiest, least expensive and best suited for “one-off analytics”. But it is also the most limited, and requires you to manage your own (external) storage and ingestion very well, which is especially hard for continuous ingestion. This makes Athena the least-suited for any ongoing, frequent use case.
Redshift, while it is arguably the most mature and feature-rich, is also the most like a traditional data warehouse in its limitations. This makes it the hardest to manage, and costly overall for traditional reporting and dashboards, and not as well suited for the newer use cases.