Support introspecting composite types #391
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| composite_types | ||
| .0 | ||
| .retain(|t, _| occurring_type_names.contains(t)); | ||
| (occurring_scalar_types, composite_types) |
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Why do we both mutate composite_types and return it?
| mut occurring_scalar_types: BTreeSet<metadata::ScalarType>, | ||
| occurring_type_names: BTreeSet<String>, | ||
| mut composite_types: metadata::CompositeTypes, | ||
| ) -> (BTreeSet<metadata::ScalarType>, metadata::CompositeTypes) { |
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The mix of mutated "in/out" parameters and return values is confusing me. I'd rather pick one or the other.
Can we just mutate occurring_type_names?
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I'm not quite sure I get this.
AFAIK a an 'out parameter' would be a &mut, right?
All parameters to this function are owned, which is also why some of them get returned afterwards.
I'm totally open to suggestions. It wasn't obvious what would be the best way to code this function TBH.
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Ah, that makes sense now. Thanks!
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I cannot promise I completely understand this SQL, but I understand it about as well as I'm ever going to.
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That's understandable. It's mostly made up of semi-internal postgres details :p
What
This PR adds the ability of the introspection query to detect composite types, meaning user-defined record types that do not arise from a table but exist as standalone definitions.
This even discovered a typo in the previous, manually crafted composite type metadata.
Support for cockroachdb is limited here until cockroachdb/cockroach#109675 is released.
How
Introspection Query now captures composite types, filtering out the tables. Making metadata json out of these is quite similar to how we already did tables, so no huge surprises here.
Occurring types logic now becomes somewhat more complex because we can no longer simply look at which type names are used in the collections we track. A composite type occurring in say, a table column, may refer to scalar types that don't occur anywhere else, and even other composite types. Occurring type discovery thus becomes an iterative procedure rather than a single pass.