![]() Though, it has external tables to use data in some specific formats stored in Amazon S3. Inheritanceįoreign data wrappers are not supported in Redshift. This may cause queries to return wrong results.ĬHECK constraints, ASSERTIONs and triggers are not supported. If there is a primary key or a UNIQUE key, COUNT(DISTINCT *) will return the same number as COUNT(*).SELECT DISTINCT pk will return the same results as SELECT pk.Instead, Redshift assumes that they are enforced by the client application, so for example: ConstraintsĬonstraints like primary key uniqueness, UNIQUE constraints and foreign keys are not enforced. Redshift allows a DISTKEY and a SORTKEY for each table (very similar to Cassandra primary keys), but there are no secondary indexes.Įven for those keys, PostgreSQL ASC and DESC options, index types, partial indexes, expressional indexes, non-key columns are not available. User-defined types, pseudo-types and domains are also not supported. Redshift does not support certain types, like: Redshift does not support the concept of extensions. As a consequence, selecting all columns ( SELECT *) or many columns causes performance penalties. Redshift stores data in a columnar fashion. Don’t try to use it for different purposes. Data analysts don’t care about such a small wait, but for an OLTP workload it would be a disaster. ![]() If a simple query that would run in less than 0.1 on PostgreSQL is run against Redshift, it could very well take 0.5 seconds, or sometimes even 1 second. However, the latency is far too high and unpredictable for OLTP workloads. LatencyĪmazon Redshift has a good throughput, and it can optimise some big queries with many joins by running them in parallel through the cluster. And since it is not open source, no one would be able to keep it alive without an agreement with the vendor. As a corner case, if Amazon’s plans change for any reason, Redshift may be retired at some point. Redshift’s future appears solid because there is interest around it, and its owner is solid. Instead, many organisations and individuals contribute to improve it and have interest in keeping it alive. One great thing about PostgreSQL is that it is not developer or owned by a company. PostgreSQL is open source, but its license does not disallow Amazon from using its codebase to build a cloud database. ![]() Redshift is not open source, nor source available. Let me stress it again: this is not meant to be a complete list.
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