QuerySchemaCatalog

The Catalog: compiles the query schema of every aggregate model this instance serves, one provider per aggregate type and model, with its compiler (by default the model sources merged, see QueryModelCompiler.of). Each storage only reports its native facts, through the storage adapter storages locates. Gateways and point reads read their schema here.

Storage facts (indexes, mappings, validators) change outside deployments, so the catalog is revalidated periodically: each schema of aggregates is reloaded and published only if it compiles, otherwise the previous one stays and the failure is reported. A model without a backend, or whose backend reports an UnavailableQueryStorageAdapter, has nothing to load or revalidate: its provider fails every load and revalidation skips it. Each dataset of datasets is compiled as its QueryModel.DATASET model, and revalidated with them.