marvinlanhenke commented on code in PR #324: URL: https://github.com/apache/iceberg-rust/pull/324#discussion_r1584513718
########## crates/integrations/datafusion/src/catalog.rs: ########## @@ -0,0 +1,97 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use std::{any::Any, collections::HashMap, sync::Arc}; + +use datafusion::catalog::{schema::SchemaProvider, CatalogProvider}; +use futures::future::try_join_all; +use iceberg::{Catalog, NamespaceIdent, Result}; + +use crate::schema::IcebergSchemaProvider; + +/// Provides an interface to manage and access multiple schemas +/// within an Iceberg [`Catalog`]. +/// +/// Acts as a centralized catalog provider that aggregates +/// multiple [`SchemaProvider`], each associated with distinct namespaces. +pub struct IcebergCatalogProvider { + /// A `HashMap` where keys are namespace names + /// and values are dynamic references to objects implementing the + /// [`SchemaProvider`] trait. + schemas: HashMap<String, Arc<dyn SchemaProvider>>, +} + +impl IcebergCatalogProvider { + /// Asynchronously tries to construct a new [`IcebergCatalogProvider`] + /// using the given client to fetch and initialize schema providers for + /// each namespace in the Iceberg [`Catalog`]. + /// + /// This method retrieves the list of namespace names + /// attempts to create a schema provider for each namespace, and + /// collects these providers into a `HashMap`. + pub async fn try_new(client: Arc<dyn Catalog>) -> Result<Self> { + // TODO: + // Schemas and providers should be cached and evicted based on time + // As of right now; schemas might become stale. Review Comment: > _There are 2 hard problems in computer science: cache invalidation, naming things, and off-by-1 errors._ - Leon Bambrick 😄the classic. I think leaving it up to the user, leads us to the issue about blocking an async call in a sync trait function? I think if we have an idea how to handle this, we can better reason about if, when, and where to cache? from the docs: > To implement [CatalogProvider](https://docs.rs/datafusion/latest/datafusion/catalog/trait.CatalogProvider.html) and [SchemaProvider](https://docs.rs/datafusion/latest/datafusion/catalog/schema/trait.SchemaProvider.html) for remote catalogs, you need to provide an in memory snapshot of the required metadata. Most systems typically either already have this information cached locally or can batch access to the remote catalog to retrieve multiple schemas and tables in a single network call. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
