// Copyright 2023 Greptime Team
//
// Licensed 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.

syntax = "proto3";

package greptime.v1.index;

option java_package = "io.greptime.v1.index";
option java_outer_classname = "Index";
option go_package = "github.com/GreptimeTeam/greptime-proto/go/greptime/v1/index";

// InvertedIndexMetas defines the metadata for an inverted index
// within an SST file.
message InvertedIndexMetas {
    // A map of tag names to their respective metadata corresponding to an individual
    // inverted index within the SST file.
    map<string, InvertedIndexMeta> metas = 1;
}

// InvertedIndexMeta contains the metadata for a specific tag's inverted index.
message InvertedIndexMeta {
    // Name of the tag associated with the inverted index.
    string name = 1;

    // Defines the number of rows per group for bitmap indexing. It determines how rows
    // are batched for indexing, with each batch corresponding to a segment in the bitmap.
    // The groups are usually of uniform size, with the exception of the final group which
    // may contain fewer rows if the total row count is not a multiple of 'row_count_in_group'.
    // Segmenting allows indexed values in the tag column to be quickly located within
    // their respective groups during a query, reducing the search space and improving
    // retrieval efficiency.
    uint64 row_count_in_group = 2;

    // The byte offset of the Finite State Transducer (FST) within the SST file.
    uint64 fst_offset = 3;

    // The size in bytes of the FST data.
    uint64 fst_size = 4;

    // The byte offset where the null bitmap for this tag starts.
    uint64 null_bitmap_offset = 5;

    // The size in bytes of the null bitmap.
    uint64 null_bitmap_size = 6;

    // Statistical information about the tag's inverted index.
    InvertedIndexStats stats = 7;
}

// InvertedIndexStats provides statistical data on a tag's inverted index.
message InvertedIndexStats {
    // The count of null entries within the tag's column.
    uint64 null_count = 1;

    // The number of distinct values within the tag's column.
    uint64 distinct_count = 2;

    // The minimum value found within the tag's column, encoded as bytes.
    bytes min_value = 3;

    // The maximum value found within the tag's column, encoded as bytes.
    bytes max_value = 4;
}