alamb commented on code in PR #10549: URL: https://github.com/apache/arrow-rs/pull/10549#discussion_r3715646493
########## parquet/src/util/prefix.rs: ########## @@ -0,0 +1,133 @@ +// 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. + +//! Shared-prefix scanning for `DELTA_BYTE_ARRAY`. + +/// Returns the length in bytes of the longest common prefix of `a` and `b`. +/// +/// `DELTA_BYTE_ARRAY` stores each value as the number of leading bytes it +/// shares with its predecessor plus the remaining suffix, so this runs once +/// per value written with that encoding. When consecutive values are +/// near-identical — the case the encoding exists for — the scan covers +/// essentially the whole value, which makes its throughput, not its overhead, +/// the thing that matters. +#[inline] +pub(crate) fn common_prefix_length(a: &[u8], b: &[u8]) -> usize { Review Comment: the key here is that this is more vectorizable, I think -- 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]
