ZENOTME commented on code in PR #129: URL: https://github.com/apache/iceberg-rust/pull/129#discussion_r1444202912
########## crates/iceberg/src/scan.rs: ########## @@ -0,0 +1,448 @@ +// 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. + +//! Table scan api. + +use crate::io::FileIO; +use crate::spec::{DataContentType, ManifestEntryRef, SchemaRef, SnapshotRef, TableMetadataRef}; +use crate::table::Table; +use crate::{Error, ErrorKind}; +use arrow_array::RecordBatch; +use futures::stream::{iter, BoxStream}; +use futures::StreamExt; + +/// Builder to create table scan. +pub struct TableScanBuilder<'a> { + table: &'a Table, + // Empty column names means to select all columns + column_names: Vec<String>, + snapshot_id: Option<i64>, +} + +impl<'a> TableScanBuilder<'a> { + pub fn new(table: &'a Table) -> Self { + Self { + table, + column_names: vec![], + snapshot_id: None, + } + } + + /// Select all columns. + pub fn select_all(mut self) -> Self { + self.column_names.clear(); + self + } + + /// Select some columns of the table. + pub fn select(mut self, column_names: impl IntoIterator<Item = impl ToString>) -> Self { + self.column_names = column_names + .into_iter() + .map(|item| item.to_string()) + .collect(); + self + } + + /// Set the snapshot to scan. When not set, it uses current snapshot. + pub fn snapshot_id(mut self, snapshot_id: i64) -> Self { + self.snapshot_id = Some(snapshot_id); + self + } + + /// Build the table scan. + pub fn build(self) -> crate::Result<TableScan> { + let snapshot = match self.snapshot_id { + Some(snapshot_id) => self + .table + .metadata() + .snapshot_by_id(snapshot_id) + .ok_or_else(|| { + Error::new( + ErrorKind::DataInvalid, + format!("Snapshot with id {} not found", snapshot_id), + ) + })? + .clone(), + None => self + .table + .metadata() + .current_snapshot() + .ok_or_else(|| { + Error::new( + ErrorKind::FeatureUnsupported, + "Can't scan table without snapshots", + ) + })? + .clone(), + }; + + let schema = snapshot.schema(self.table.metadata())?; + + // Check that all column names exist in the schema. + if !self.column_names.is_empty() { + for column_name in &self.column_names { + if schema.field_by_name(column_name).is_none() { + return Err(Error::new( + ErrorKind::DataInvalid, + format!("Column {} not found in table.", column_name), + )); + } + } + } + + Ok(TableScan { + snapshot, + file_io: self.table.file_io().clone(), + table_metadata: self.table.metadata_ref(), + column_names: self.column_names, + schema, + }) + } +} + +/// Table scan. +#[derive(Debug)] +#[allow(dead_code)] +pub struct TableScan { + snapshot: SnapshotRef, + table_metadata: TableMetadataRef, + file_io: FileIO, + column_names: Vec<String>, + schema: SchemaRef, +} + +/// A stream of [`FileScanTask`]. +pub type FileScanTaskStream = BoxStream<'static, crate::Result<FileScanTask>>; + +impl TableScan { + /// Returns a stream of file scan tasks. + pub async fn plan_files(&self) -> crate::Result<FileScanTaskStream> { + let manifest_list = self + .snapshot + .load_manifest_list(&self.file_io, &self.table_metadata) Review Comment: > But we still need to write manifest files, seems not quite attractive? Oh, yes. Can we depend on manifest file directly? -- 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
