DerGut commented on code in PR #3000: URL: https://github.com/apache/iceberg-rust/pull/3000#discussion_r3799863680
########## crates/integrations/datafusion/src/catalog_access.rs: ########## @@ -0,0 +1,192 @@ +// 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::collections::HashMap; +use std::sync::Arc; + +use async_trait::async_trait; +use datafusion::catalog::Session; +use datafusion::error::Result as DFResult; +use iceberg::table::Table; +use iceberg::{ + Catalog, Namespace, NamespaceIdent, Result, SessionCatalog, SessionContext, TableCommit, + TableCreation, TableIdent, +}; + +use crate::SessionContextResolver; + +/// Describes how the DataFusion integration accesses an Iceberg catalog. +/// +/// A catalog can either be accessed directly through [`Catalog`] or through a +/// [`SessionCatalog`] bound to an Iceberg [`SessionContext`]. Operations that +/// receive a DataFusion session resolve and bind its context once. Operations +/// for which DataFusion provides no session reuse one anonymous fallback +/// context so session-scoped catalog state remains stable across those calls. +#[derive(Clone, Debug)] +pub(crate) enum CatalogAccess { + /// A catalog accessed directly through the [`Catalog`] API. + Direct(Arc<dyn Catalog>), + + /// A session-aware catalog, its resolver, and the stable context used by + /// DataFusion APIs that do not expose a session. + SessionAware { + catalog: Arc<dyn SessionCatalog>, + resolver: Arc<dyn SessionContextResolver>, + fallback_context: SessionContext, + }, +} + +impl CatalogAccess { + pub(crate) fn with_session(&self, session: &dyn Session) -> DFResult<Arc<dyn Catalog>> { Review Comment: > Do we plan to have default implementations for SessionContextResolver? How do users use RestSessionCatalog out of the box? Unfortunately, due to Datafusion's nature of handling query sessions, there's little we can provide as default implementations. A `datafusion::catalog::Session` does provide a [`Session::session_id`](https://docs.rs/datafusion/latest/datafusion/catalog/trait.Session.html#tymethod.session_id) which we can use to populate the `SessionContext::session_id`. But IMO an otherwise empty context has no use, so I don't see a point in providing a default implementation for that. Also, I'm afraid that since all Datafusion query metadata is user-defined, there's no reason for users to use a `SessionCatalog` over a `Catalog` unless they also provide a mechanism to extract+translate that metadata. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
