![]() When the Amazon S3 files are updated, the data is immediately available for query. This means the same data stored in S3 can be queried by any Redshift cluster in the same AWS region. Redshift Spectrum Tables can be added to multiple Amazon Redshift clusters. Keep in mind that these tables are read only. After the Redshift tables have been defined, tables can be queried and joined, like any other Redshift table. This means defining partitions as part of the external table can improve performance. If the data is partitioned, the query plan will know what data it needs and, just as importantly, know what data to skip. When Redshift executes a query, it creates a query plan. Though, it's a good idea to partition data. Optionally, the external tables can be partitioned on one or more columns. While Amazon Athena and Redshift Spectrum are designed to query data stored in Amazon S3 using standard SQL, the two tools have some key differences. Changes to the external data catalog are immediately available to Amazon Redshift. The data catalog that comes with Amazon Athena or an Apache Hive Metastore.Įxternal tables can be created and managed, either by using Redshift's data definition language commands, or with any other tool that can connect to the external data catalog. You can think of it as an external table. Redshift Spectrum Tables are created by defining the structure of external files and then registering them as tables in an external data catalog. Because of this, Redshift Spectrum Queries use much less of a cluster's processing capacity than other queries because compute-intensive activity is pushed into the spectrum nodes.īased on the demands of queries, Redshift Spectrum can potentially scale to use thousands of spectrum nodes to take advantage of Redshift's massively parallel processing architecture. ![]() ![]() Amazon Redshift Spectrum nodes are dedicated Amazon Redshift Servers managed by AWS that are independent of customer-provisioned clusters. That's the high-level explanation of what happens. Essentially, the data stored in S3 is formatted like a Redshift table and cataloged with something like AWS Glue. How does Redshift Spectrum work? It almost seems like magic. ![]()
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