From Heuristics to Statistics: How we built a cost-based optimizer for CockroachDB
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Using a declarative language like SQL with a relational database provides many benefits since it creates separation between the logical representation of the database and the physical representation. It gives us the ability to change the physical layout of the data without changing the queries or applications that use the database.
But it also means we need to bridge that gap somehow, and that’s where something like a query optimizer comes in. Query optimizers use statistics to find the lowest cost alternative among several possible execution plans. In this talk, CockroachDB Engineer Rebecca Taft will walk through the limitations of a heuristics-based planner and the development of CockroachDB’s cost-based query optimizer. She will conclude the talk by giving a preview of what the query optimizer team at Cockroach Labs plans to tackle next: making the optimizer choose the best execution plan even when the data in the database is distributed across the globe.
- 50 min
- Postgres Conference 2020
- Distributed SQL