Convert Region Allocation to be a CTE#1733
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This is awesome! A few questions, two suggestions, but none blocking.
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Just confirmed that this fixes the symptom of https://github.com/oxidecomputer/remote-access-preview/issues/23 |
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Fixes #1688
This PR can basically be read in two pieces - I could literally split it in two if that would be helpful, but figured I'd show "new utilities" with "how they are utilized for the region allocation use-case specifically".
Part 1: Utilities to build CTEs
nexus/src/db/subquery.rs- Adds the definition of traits likeSubquery, as well as aCteBuilderto help building arbitrary CTEs.nexus/db-macros/src/lib.rs- Adds macro to deriveSubquery(identifying that a query can be used in a CTE arm)nexus/db-macros/src/subquery.rs- Implementation ofSubquerymacronexus/src/db/alias.rs- Defines expression which allows field aliasing (FOO as BARin SELECT/RETURNING queries)Part 2: Using those utilities to implement the region allocation CTE
nexus/src/db/datastore/region.rs- Updates actual usage of region allocation querynexus/src/db/queries/region_allocation.rs- Defines and implements region allocation CTEnexus/db-model/src/queries/region_allocation.rs- Defines model of subqueries (usingtable!macro)Note: This particular CTE is actually kinda long, because the transaction was doing a lot. In the future, however, we'll be able to simplify the CTE significantly by relying on quotas/reservations and db constraints to help enforce some of the size limits.