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Comment by iblaine | Hacker News Reader

For anyone wondering, OLAP != OLAP Cubes

OLAP = A category of databases meant for analyzing data. These are eventually consistent db's, and not OLTP db's. OLAP db's include Redshift, Teradata, Snowflake, BigQuery, and others. Generally what makes a database an MPP database is partitioning compute and storage. Generally what differentiates one MPP db from another is whether or not data and compute are colocated.

OLAP Cubes = A feature built into SQL Server, that includes has its own dialect of SQL called MDX. OLAP Cubes are decreasing in popularity because you can achieve the same results through other means and less effort.

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Thank you for saying this! I think your definition of OLAP is good, but the definition of OLAP cube could simply be 'a data structure that is basically a very sophisticated nested array'. I'm oversimplifying, of course — there are over four decades of work at this point on OLAP cubes, including various compression schemes (e.g. https://link.springer.com/chapter/10.1007/978-3-642-17569-5_...) and other techniques to aggregate data when the cube outstrips the hosts's memory. But by and large it is important to understand that an OLAP cube is simply a data structure ... and different vendors have different implementations and optimisations of said data structure.

I think this confusion exists because too many vendors conflate the two terms. They say OLAP when they mean OLAP cube. BigQuery and Redshift, however, do not: they are very clear that their dbs are designed for OLAP workloads but are not cubes.

Redshift is not eventually consistent, it's fully ACID compliant.

You are correct, and eventually consistent is a hand-wavy description of Redshift. While Redshift is ACID compliant, it squarely belongs in the category of OLAP db's and not OLTP db.s

Not unique to MS SQL Server - Oracle and IBM (InfoSphere) have cube engines, and there have been independent implementations as well: https://en.wikipedia.org/wiki/Comparison_of_OLAP_servers

That’s a valid point. Thanks.

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