lance 0.5.8

A columnar data format that is 100x faster than Parquet for random access.
Documentation 
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// 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 crate::io::object_store::ObjectStoreParams;

/// The mode to write dataset.
#[derive(Debug, Clone, Copy)]
pub enum WriteMode {
    /// Create a new dataset. Expect the dataset does not exist.
    Create,
    /// Append to an existing dataset.
    Append,
    /// Overwrite a dataset as a new version, or create new dataset if not exist.
    Overwrite,
}

/// Dataset Write Parameters
#[derive(Debug, Clone)]
pub struct WriteParams {
    /// Max number of records per file.
    pub max_rows_per_file: usize,

    /// Max number of rows per row group.
    pub max_rows_per_group: usize,

    /// Write mode
    pub mode: WriteMode,

    pub store_params: Option<ObjectStoreParams>,
}

impl Default for WriteParams {
    fn default() -> Self {
        Self {
            max_rows_per_file: 1024 * 1024, // 1 million
            max_rows_per_group: 1024,
            mode: WriteMode::Create,
            store_params: None,
        }
    }
}