在 MongoDB 5.0、c# 驱动程序中过滤基于时间的数据：得到错误（零）结果

Question

我有一个用 MongoDB5.0 引入的 TimeSeries 集合，里面装满了大约 100000 个文档，并希望过滤器工作，例如获取集合内特定时间范围的文档计数。

// Timestamp must be a BSON date (as the doc's say), which is BSONDateTime in c#
// so the time range boundaries for the filter is based on the BSon Default 1/1/1970
// from, to are TimeSpan objects

var dt1 = new DateTime(1970,1,1,0,0,0, DateTimeKind.Utc) + from;
var dt2= new DateTime(1970,1,1,0,0,0, DateTimeKind.Utc) + to;

var filter = Builders<MongoTimeSeriesDocument>.Filter.Gte(x => x.Timestamp, dt1);
filter &= Builders<MongoTimeSeriesDocument>.Filter.Lte(x => x.Timestamp, dt2);

// result: zero
var docCount = await collection.CountDocumentsAsync(filter)
                .ConfigureAwait(false);
// result: zero
var docCount2 = await collection.Find(filter)
                .CountDocumentsAsync()
                .ConfigureAwait(false);

我还注册了一个 DateTimeSeriealizer：

BsonSerializer.RegisterSerializer(typeof(DateTime), new DateTimeSerializer(DateTimeKind.Utc));

序列化程序不起作用。

这有效：

// result: 70000
var docCount = await collection.CountDocumentsAsync(x => x.Timestamp < new DateTime(2021,11,7,0,0,0, DateTimeKind.Utc))
                .ConfigureAwait(false);

虽然这不起作用（它应该算全部，因为时间戳 > 1970）：

// result: 0
var docCount2 = await collection.CountDocumentsAsync(x => x.Timestamp > new DateTime(1970,1,1,0,0,0, DateTimeKind.Utc))
                .ConfigureAwait(false);
// same with BsonDateTime: result: 0
var docCount2 = await collection.CountDocumentsAsync(x => x.Timestamp > new BsonDateTime(new DateTime(1970,1,1,0,0,0, DateTimeKind.Utc)))
                .ConfigureAwait(false);

Answer 1

在 C# 中，我采用 Bson 方式并传递一个$match字符串，该字符串有 2 个表示$gte和$lte表达式。 这适用于 TimeSeries：

var filterStage = new StringBuilder();
            filterStage.Append("{$match:{$and:[ {$expr: {$gte:");
            filterStage.Append("[ \"$Timestamp\",");
            filterStage.Append($"ISODate('{isoFrom}'),");
            filterStage.Append("]}}, {$expr:{ $lte:");
            filterStage.Append("[ \"$Timestamp\",");
            filterStage.Append($"ISODate('{isoTo}')");
            filterStage.Append("]}} ]}}");

            var aggregation = await collection.Aggregate()
                .AppendStage<MongoTimeSeriesDocument>(filterStage.ToString())
                .ToListAsync()
                .ConfigureAwait(false);