tustvold commented on code in PR #7842: URL: https://github.com/apache/arrow-datafusion/pull/7842#discussion_r1369058242
########## datafusion/physical-plan/src/sorts/batches.rs: ########## @@ -0,0 +1,124 @@ +// 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 super::cursor::{Cursor, CursorValues}; + +/// A representation of a record batch, +/// passable and sliceable through multiple merge nodes +/// in a cascaded merge tree. +/// +/// A `BatchCursor` encapsulates the ability to sort merge each +/// sliced portition of a record batch, with minimal overhead. +/// +/// ```text +/// ┌────────────────────────┐ +/// │ CursorValues Batch │ ┌──────────────────────┐ +/// │ ┌──────────┐ ┌───────┐ │ ─ ─ ─ ▶│ BatchTracker │ +/// │ │ 1..10 │ │ A │ ┼ ─ │ └──────────────────────┘ +/// │ ├──────────┤ ├───────┤ │ │ Holds batches +/// │ │ 11..20 │ │ B │ ┼ ─ ┘ and assigns BatchId +/// │ └──────────┘ └───────┘ │ +/// └────────────────────────┘ +/// │ +/// │ +/// ▼ +/// BatchCursors +/// ┌────────────────────────┐ ┌──────────────────────┐ ─ ▶ push batch +/// │ Cursor BatchId │ ─ ─ ─ ▶│ LoserTree (Merge) │ ─ ▶ advance cursor +/// │ ┌──────────┐ ┌───────┐ │ │ └──────────────────────┘ ─ ▶ push row +/// │ │ 1..10 │ │ A │ ┼ ─ │ ┌──────────────────────┐ │ +/// │ ├──────────┤ ├───────┤ │ │ │ SortOrderBuilder ◀┼ ─ ─ ─ ─ ┘ +/// │ │ 11..20 │ │ B │ ┼ ─ ┘ └──────────────────────┘ +/// │ └──────────┘ └───────┘ │ holds sorted rows +/// └────────────────────────┘ up to ceiling size N +/// │ +/// ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┘ +/// │ +/// ▼ +/// BatchCursors Review Comment: I'm not sure of a better name, but to me `BatchCursor` would suggest this construction owns a `RecordBatch` and is a cursor over it, which isn't the case. Perhaps we might also be able to work the slice aspect in there, as I _think_ that is what they are. Perhaps we could rename `BatchCursors` to `SortOrder` and have that as the abstraction? Or is per-slice access required somehow? -- 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]
