riegeli_metadata.proto

// Copyright 2022 Google LLC
//
// 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 = "proto2";

package kv_server;

import "public/base_types.proto";
import "riegeli/records/records_metadata.proto";

// Metadata specific to DELTA files.
message DeltaMetadata {}

// Metadata specific to SNAPSHOT files.
message SnapshotMetadata {
  // [Required]
  // (1) Name of the previous snapshot file used to generate this snapshot or
  // (2) Name of the oldest delta file included in the snapshot.
  optional string starting_file = 1;

  // [Required]
  // Name of the most recent delta file included in the snapshot.
  optional string ending_delta_file = 2;
}

// Sharding metadata for DELTA and SNAPSHOT files.
message ShardingMetadata {
  // The shard number that data in this file belong to.
  optional int64 shard_num = 1;
}

// Metadata specific to LOGICAL_SHARDING_CONFIG files.
message LogicalShardingConfigMetadata {
  // [Required] Number of logical shards, recommended to be a power of 2 and
  // much larger than `num_physical_shards`. Data records are assigned to
  // logical shards and logical shards map to physical shards (actual data
  // servers).
  optional int32 num_logical_shards = 1;

  // [Required] Number of physical shards. Maps to actual physical data servers
  // that store data records. Each physical shard can be responsible for data
  // records assigned to different logical shards.
  optional int32 num_physical_shards = 2;

  // [Required] sha256sum of the mapping between logical shards and physical
  // shards. This is fixed for each logical sharding config file, but can be
  // different between files with the same number of logical and physical
  // shards.
  optional string shard_mapping_sha256sum = 3;

  // [Required] Unix timestamp when the logical sharding config file was
  // created.
  optional int64 creation_timestamp = 4;
}

// All K/V server metadata related to one riegeli file.
message KVFileMetadata {
  // All records in one file are from this namespace.
  optional KeyNamespace.Enum key_namespace = 1 [deprecated = true];

  oneof file_type {
    DeltaMetadata delta = 2;
    SnapshotMetadata snapshot = 3;
    LogicalShardingConfigMetadata logical_sharding_config = 5;
  }

  optional ShardingMetadata sharding_metadata = 4;
}

extend riegeli.RecordsMetadata {
  optional KVFileMetadata kv_file_metadata = 20220706;
}