// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright The Lance Authors


syntax = "proto3";

package lance.encodings_datafusion;

import "encodings.proto";

// ZoneMaps are a way to wrap any leaf array with a set of zone maps that
// can be used to apply pushdown filtering.
//
// A "zone map" is the min/max/null_count of a set of rows.  This can be
// used to quickly filter out zones which are not included in simple predicates
// like 'x = 5' or 'x > 10'.
message ZoneMaps {

    // How many rows are covered by each zone map.  There will be
    // ceil_div(num_rows, rows_per_map) zone maps.
    uint32 rows_per_map = 1;

    // The zone maps are encoded as struct arrays with 1 row per zone.  This
    // should be stored in a column metadata buffer.  The struct array should
    // have 3 children: min: T, max: T, null_count: u32
    lance.encodings.ArrayEncoding stats = 2;
    
    // The underlying array values
    lance.encodings.ArrayEncoding values = 5;
}