[oximeter] Policy to redirect DB reads #7522
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karencfv
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Thanks for tackling this, it looks like a great start!
I have two general naming suggestions. First, I think we should use read instead of reads everywhere. "Reads" sounds like a verb to me, and read/write seems like a more familiar pair of terms than reads/writes.
Second, I think (but please correct me if I'm mistaken) that your version field is basically a generation number, so I think it should be called generation (or something like that) and use the provided Generation API types. We seem to be converging on semantic versions everywhere, so I think the term version should probably be reserved for those.
| sql_query( | ||
| r"INSERT INTO oximeter_reads_policy | ||
| (version, oximeter_reads_mode, time_created) | ||
| SELECT $1, $2, $3 | ||
| FROM oximeter_reads_policy WHERE version = $4 AND version IN | ||
| (SELECT version FROM oximeter_reads_policy | ||
| ORDER BY version DESC LIMIT 1)", | ||
| ) |
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Totally up to you, but if you want to stick to the diesel typed universe, @jgallagher just showed me how to wrangle basically this same query in #7518.
| .authorize(authz::Action::Modify, &authz::BLUEPRINT_CONFIG) | ||
| .await?; | ||
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| let num_inserted = if policy.version == 1 { |
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Again completely up to you, but I initially had this same kind of no-rows/some-rows split in #7518, and found that it simplified a lot of things to insert a default row (single_node in this case, probably) as part of the schema migration so that there was always guaranteed to be at least one row.
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Thanks for the review @plotnick!
I have two general naming suggestions. First, I think we should use read instead of reads everywhere. "Reads" sounds like a verb to me, and read/write seems like a more familiar pair of terms than reads/writes.
Yeah, that makes sense. Now that I look at it I don't really know why I used "reads" in the first place 😄
Second, I think (but please correct me if I'm mistaken) that your version field is basically a generation number, so I think it should be called generation (or something like that) and use the provided Generation API types. We seem to be converging on semantic versions everywhere, so I think the term version should probably be reserved for those.
Hm, I used "version" because I saw it being used in other places https://github.com/oxidecomputer/omicron/blob/main/nexus/db-model/src/deployment.rs#L113-L117 https://github.com/oxidecomputer/omicron/blob/main/nexus/db-model/src/deployment.rs#L60-L70 https://github.com/oxidecomputer/omicron/blob/main/nexus/db-model/src/clickhouse_policy.rs#L31-L37 🤔
| @@ -17,7 +17,7 @@ use std::collections::BTreeMap; | |||
| /// | |||
| /// This must be updated when you change the database schema. Refer to | |||
| /// schema/crdb/README.adoc in the root of this repository for details. | |||
| pub const SCHEMA_VERSION: SemverVersion = SemverVersion::new(123, 0, 0); | |||
| pub const SCHEMA_VERSION: SemverVersion = SemverVersion::new(124, 0, 0); | |||
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Note to self: Make sure this version is still correct at time of merging
Closes: #7420