如何在LiteDB数据库中合理存储元数据？求更优实现方案

现有方案概述 #

我正在使用独立LiteDB数据库，需要为每个数据库添加额外元数据。当前采用仅含单个对象的专用集合存储，代码如下：

定义DBInfo类 #

internal class DBInfo {
    public int Id { get; set; }
    public Guid UId { get; set; } = Guid.NewGuid();
    public string Source { get; set; } = string.Empty;
    public DateTime DTCreated { get; set; } = DateTime.UtcNow;
}

创建数据库时插入元数据 #

_db = new LiteDatabase(dbPath);

var dbInfoCollection = _db.GetCollection<DBInfo>();
var dbInfo = new DBInfo();
dbInfo.Source = "company 1";
dbInfoCollection.Insert(dbInfo);
dbInfoCollection.Update(dbInfo);

_db.Commit();

读取元数据 #

_db = new LiteDatabase(dbPath);
var dbInfo = _db.GetCollection<DBInfo>().FindAll().Single();
Console.WriteLine($"Source of current database: {dbInfo.Source}");

该方案可正常运行，但不够理想，希望找到更合理的实现方式。

优化实现方案 #

1. 使用内置UserVersion属性 #

LiteDB提供数据库级别的UserVersion整数字段，适合存储简单版本标识类信息：

设置UserVersion

_db = new LiteDatabase(dbPath);
_db.Pragma.UserVersion = 1; // 用整数存储版本或简单编码信息
_db.Commit();

读取UserVersion

_db = new LiteDatabase(dbPath);
var version = _db.Pragma.UserVersion;
Console.WriteLine($"Database version: {version}");

2. 简化专用集合方案（固定单文档） #

对现有方案优化，通过固定ID确保集合仅存一个文档，避免Single()查询的潜在问题：

调整DBInfo类（固定ID）

internal class DBInfo {
    public int Id { get; set; } = 1; // 固定ID，保证唯一文档
    public Guid UId { get; set; } = Guid.NewGuid();
    public string Source { get; set; } = string.Empty;
    public DateTime DTCreated { get; set; } = DateTime.UtcNow;
}

插入/更新元数据

_db = new LiteDatabase(dbPath);
var dbInfoCollection = _db.GetCollection<DBInfo>("DBInfo");
var dbInfo = dbInfoCollection.FindById(1);

if (dbInfo == null)
{
    dbInfo = new DBInfo { Source = "company 1" };
    dbInfoCollection.Insert(dbInfo);
}
else
{
    dbInfo.Source = "updated company";
    dbInfoCollection.Update(dbInfo);
}

_db.Commit();

读取元数据

_db = new LiteDatabase(dbPath);
var dbInfo = _db.GetCollection<DBInfo>("DBInfo").FindById(1);
if (dbInfo != null)
{
    Console.WriteLine($"Source: {dbInfo.Source}");
}

3. 用Pragma.Custom存储序列化元数据 #

利用Pragma.Custom字段存储任意字符串，可序列化复杂元数据结构：

设置自定义元数据

_db = new LiteDatabase(dbPath);
var dbInfo = new DBInfo { Source = "company 1" };
var json = System.Text.Json.JsonSerializer.Serialize(dbInfo);
_db.Pragma.Custom = json;
_db.Commit();

读取自定义元数据

_db = new LiteDatabase(dbPath);
var json = _db.Pragma.Custom;
if (!string.IsNullOrEmpty(json))
{
    var dbInfo = System.Text.Json.JsonSerializer.Deserialize<DBInfo>(json);
    Console.WriteLine($"Source: {dbInfo.Source}");
}

4. 利用FileStorage存储元数据文件 #

若元数据需和其他资源关联，可使用LiteDB的文件存储功能：

存储元数据文件

_db = new LiteDatabase(dbPath);
var dbInfo = new DBInfo { Source = "company 1" };
var json = System.Text.Json.JsonSerializer.Serialize(dbInfo);

using var ms = new MemoryStream(Encoding.UTF8.GetBytes(json));
_db.FileStorage.Upload("metadata/dbinfo.json", "DB Metadata", ms);
_db.Commit();

读取元数据文件

_db = new LiteDatabase(dbPath);
var file = _db.FileStorage.FindById("metadata/dbinfo.json");
if (file != null)
{
    using var ms = new MemoryStream();
    file.CopyTo(ms);
    ms.Position = 0;
    var json = new StreamReader(ms).ReadToEnd();
    var dbInfo = System.Text.Json.JsonSerializer.Deserialize<DBInfo>(json);
    Console.WriteLine($"Source: {dbInfo.Source}");
}

内容的提问来源于stack exchange，提问作者Spark13