我正在运行一个 cron 作业，在晚上从 MongoDB 查询一些数据，当没有其他人使用 MongoDB 读取或写入数据时，我收到此错误。
Error: server.lab:27017: Read timed out after reading 0 bytes, waited for 30.000000 seconds
白天查询持续约 60 毫秒才能返回数据。我有足够的 RAM，即使将其加倍也无济于事。MongoDB 在 XFS 文件系统上运行。我使用版本 3.2.3（最新版本）。我知道 MongoDB 使用 linux 缓存，问题很可能是 MongoDB 的预热机制。我还能做什么？
这是查询。
db.event.aggregate([
{
$match : {"schedule.sessions.attendance.0" : {$exists : true}}
},
{
$unwind : "$schedule"
},
{
$unwind : "$schedule.sessions"
},
{
$project : {
'_id' : false,
'schedule.sessions.date_start' : 1,
'schedule.sessions.date_finish' : 1,
'schedule.sessions.attendance' : 1
}
},
{
$match : {
"schedule.sessions.attendance.0" : {$exists : true},
'schedule.sessions.date_start' : {$gte : ISODate("2016-02-14T20:00:00.000+0000"), $lt : ISODate("2016-02-15T20:00:00.000+0000") }
}
}
])
事件集合包含大约 5000 个文档。
以下是文档的结构
mongos> db.event.findOne()
{
"_id" : ObjectId("563cc6993764872c268b45db"),
"schedule" : [
{
"_id" : ObjectId("563cc6993764872c268b45d7"),
"sessions" : [
{
"_id" : ObjectId("5694d3c842600772f64bcc1a"),
"date_start" : ISODate("2016-02-08T11:30:00Z"),
"date_finish" : ISODate("2016-02-08T13:30:00Z"),
"place" : [ ],
"attendance" : [
ObjectId("55ed6d03b3b852c812003b92"),
ObjectId("55ed6ce1b3b852c8120023f2"),
ObjectId("55eee520b3b852ac930003cb"),
ObjectId("55ed6cfdb3b852c812003722"),
ObjectId("55ed6d01b3b852c812003a52"),
ObjectId("55ed6d01b3b852c812003a7d")
],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
]
},
{
"_id" : ObjectId("563cc6993764872c268b45d8"),
"sessions" : [
{
"_id" : ObjectId("5694d3c842600772f64bcc1b"),
"date_start" : ISODate("2016-02-15T11:30:00Z"),
"date_finish" : ISODate("2016-02-15T13:30:00Z"),
"place" : [ ],
"attendance" : [
ObjectId("55ed6d03b3b852c812003b92"),
ObjectId("55ed6ce1b3b852c8120023f2"),
ObjectId("55eee520b3b852ac930003cb"),
ObjectId("55ed6cfdb3b852c812003722"),
ObjectId("55ed6d01b3b852c812003a7d")
],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
]
},
{
"_id" : ObjectId("563cc6993764872c268b45d9"),
"sessions" : [
{
"_id" : ObjectId("5694d3c842600772f64bcc1c"),
"date_start" : ISODate("2016-02-22T11:30:00Z"),
"date_finish" : ISODate("2016-02-22T13:30:00Z"),
"place" : [ ],
"attendance" : [ ],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
]
},
{
"_id" : ObjectId("563cc6993764872c268b45da"),
"sessions" : [
{
"_id" : ObjectId("5694d3c842600772f64bcc1d"),
"date_start" : ISODate("2016-02-29T11:30:00Z"),
"date_finish" : ISODate("2016-02-29T13:30:00Z"),
"place" : [ ],
"attendance" : [ ],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
]
},
{
"_id" : ObjectId("56b9d21c376487714d2c1c0a"),
"sessions" : [
{
"_id" : ObjectId("56b9d21c376487714d2c1c09"),
"date_start" : ISODate("2016-02-14T11:30:00Z"),
"date_finish" : ISODate("2016-02-14T13:30:00Z"),
"place" : [ ],
"attendance" : [
ObjectId("55ed6d03b3b852c812003b92"),
ObjectId("55ed6ce1b3b852c8120023f2"),
ObjectId("55eee520b3b852ac930003cb"),
ObjectId("55ed6cfdb3b852c812003722"),
ObjectId("55ed6d01b3b852c812003a7d")
],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
],
"date_created" : ISODate("2016-02-09T11:48:44.400Z"),
"date_updated" : ISODate("2016-02-09T11:48:44.400Z"),
"shard_location_id" : null
},
{
"_id" : ObjectId("56b9d24c376487794e2c1c0a"),
"sessions" : [
{
"_id" : ObjectId("56b9d24c376487794e2c1c09"),
"date_start" : ISODate("2016-02-21T11:30:00Z"),
"date_finish" : ISODate("2016-02-21T13:30:00Z"),
"place" : [ ],
"attendance" : [ ],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
],
"date_created" : ISODate("2016-02-09T11:49:32.324Z"),
"date_updated" : ISODate("2016-02-09T11:49:32.324Z"),
"shard_location_id" : null
},
{
"_id" : ObjectId("56b9d2583764870e4e2c1c0b"),
"sessions" : [
{
"_id" : ObjectId("56b9d2583764870e4e2c1c0a"),
"date_start" : ISODate("2016-02-28T11:30:00Z"),
"date_finish" : ISODate("2016-02-28T13:30:00Z"),
"place" : [ ],
"attendance" : [ ],
"date_created" : null,
"date_updated" : null,
"shard_location_id" : null
}
],
"date_created" : ISODate("2016-02-09T11:49:44.108Z"),
"date_updated" : ISODate("2016-02-09T11:49:44.108Z"),
"shard_location_id" : null
},
{
"_id" : ObjectId("56c47ff416d37ce33f1e8144"),
"sessions" : [
{
"_id" : ObjectId("56c47ff416d37ce33f1e8143"),
"date_start" : ISODate("2016-03-06T11:30:00Z"),
"date_finish" : ISODate("2016-03-06T13:30:00Z"),
"place" : [ ],
"attendance" : [ ],
"date_created" : ISODate("2016-02-17T14:13:08.652Z"),
"date_updated" : ISODate("2016-02-17T14:13:08.652Z"),
"shard_location_id" : null
}
],
"date_created" : ISODate("2016-02-17T14:13:08.652Z"),
"date_updated" : ISODate("2016-02-17T14:13:08.652Z"),
"shard_location_id" : null
}
],
"subscription" : [
{
"_id" : ObjectId("56af42ff16d37c4901afc81d"),
"user_id" : ObjectId("55ed6d00b3b852c8120039e7"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:35:27.324Z"),
"date_updated" : ISODate("2016-02-01T11:35:27.324Z")
},
{
"_id" : ObjectId("56af441958f591da05954741"),
"user_id" : ObjectId("55eee515b3b852ac9300024a"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:40:09.034Z"),
"date_updated" : ISODate("2016-02-01T11:40:09.034Z")
},
{
"_id" : ObjectId("56af44b6f5417201179f6822"),
"user_id" : ObjectId("55ed6cfcb3b852c8120036b5"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:42:46.296Z"),
"date_updated" : ISODate("2016-02-01T11:42:46.296Z")
},
{
"_id" : ObjectId("56af450d16d37cb20aafc83c"),
"user_id" : ObjectId("55ed6d03b3b852c812003b92"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:44:13.048Z"),
"date_updated" : ISODate("2016-02-01T11:44:13.048Z")
},
{
"_id" : ObjectId("56af4543f541728c1a9f67d5"),
"user_id" : ObjectId("55ed6ce9b3b852c812002924"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:45:07.372Z"),
"date_updated" : ISODate("2016-02-01T11:45:07.372Z")
},
{
"_id" : ObjectId("56af458a16d37cb20aafc8c1"),
"user_id" : ObjectId("55ed6cffb3b852c812003912"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:46:18.765Z"),
"date_updated" : ISODate("2016-02-01T11:46:18.765Z")
},
{
"_id" : ObjectId("56af4612f54172991d9f67f5"),
"user_id" : ObjectId("55ed6cd6b3b852c812001b93"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:48:34.755Z"),
"date_updated" : ISODate("2016-02-01T11:48:34.755Z")
},
{
"_id" : ObjectId("56af45f116d37c680fafc8e3"),
"user_id" : ObjectId("55ed6cfdb3b852c812003723"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:48:01.395Z"),
"date_updated" : ISODate("2016-02-01T11:48:01.395Z")
},
{
"_id" : ObjectId("56af46bc16d37c2f11afc8ac"),
"user_id" : ObjectId("55eee513b3b852ac9300020a"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:51:24.653Z"),
"date_updated" : ISODate("2016-02-01T11:51:24.653Z")
},
{
"_id" : ObjectId("56af46e2376487b31fa41f34"),
"user_id" : ObjectId("55eee519b3b852ac930002ca"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:52:02.953Z"),
"date_updated" : ISODate("2016-02-01T11:52:02.953Z")
},
{
"_id" : ObjectId("56af4756f5417214259f67c0"),
"user_id" : ObjectId("55ed6ce1b3b852c8120023f2"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:53:58.595Z"),
"date_updated" : ISODate("2016-02-01T11:53:58.595Z")
},
{
"_id" : ObjectId("56af477af5417261259f67c3"),
"user_id" : ObjectId("55eee520b3b852ac930003cb"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:54:34.308Z"),
"date_updated" : ISODate("2016-02-01T11:54:34.308Z")
},
{
"_id" : ObjectId("56af478e376487a822a41f52"),
"user_id" : ObjectId("55ed6d04b3b852c812003c02"),
"status" : "approved",
"type" : NumberLong(2),
"date_created" : ISODate("2016-02-01T11:54:54.084Z"),
"date_updated" : ISODate("2016-02-01T11:54:54.084Z")
},
{
"_id" : ObjectId("56b87f27f54172375e7b23cb"),
"user_id" : ObjectId("55ed6ce1b3b852c812002389"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:42:31.240Z"),
"date_updated" : ISODate("2016-02-08T11:42:31.240Z"),
"shard_location_id" : NumberLong(60074372)
},
{
"_id" : ObjectId("56b87f27f54172375e7b23cc"),
"user_id" : ObjectId("55ed6cdcb3b852c81200202d"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:42:31.269Z"),
"date_updated" : ISODate("2016-02-08T11:42:31.269Z"),
"shard_location_id" : NumberLong(85072479)
},
{
"_id" : ObjectId("56b87f27f54172375e7b23ce"),
"user_id" : ObjectId("55ed6cdab3b852c812001ea6"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:42:31.299Z"),
"date_updated" : ISODate("2016-02-08T11:42:31.299Z"),
"shard_location_id" : NumberLong(54819081)
},
{
"_id" : ObjectId("56b87f27f54172375e7b23cf"),
"user_id" : ObjectId("55ed6cdbb3b852c812001fba"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:42:31.331Z"),
"date_updated" : ISODate("2016-02-08T11:42:31.331Z"),
"shard_location_id" : NumberLong(65625871),
"status_deleted" : NumberLong(1)
},
{
"_id" : ObjectId("56b87f27f54172375e7b23d0"),
"user_id" : ObjectId("55ed6ce9b3b852c812002929"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:42:31.360Z"),
"date_updated" : ISODate("2016-02-08T11:42:31.360Z"),
"shard_location_id" : NumberLong(79641334)
},
{
"_id" : ObjectId("56b87f27f54172375e7b23d1"),
"user_id" : ObjectId("55ed6cfab3b852c812003504"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:42:31.388Z"),
"date_updated" : ISODate("2016-02-08T11:42:31.388Z"),
"shard_location_id" : NumberLong(94737821)
},
{
"_id" : ObjectId("56b8806df5417242647b23c7"),
"user_id" : ObjectId("55ed6cfeb3b852c812003845"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.320Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.320Z"),
"shard_location_id" : NumberLong(66955040)
},
{
"_id" : ObjectId("56b8806df5417242647b23c8"),
"user_id" : ObjectId("55ed6cfab3b852c812003596"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.349Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.349Z"),
"shard_location_id" : NumberLong(83983525)
},
{
"_id" : ObjectId("56b8806df5417242647b23c9"),
"user_id" : ObjectId("55ed6d00b3b852c8120039ac"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.544Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.544Z"),
"shard_location_id" : NumberLong(70202545),
"status_deleted" : NumberLong(1)
},
{
"_id" : ObjectId("56b8806df5417242647b23ca"),
"user_id" : ObjectId("55ed6d03b3b852c812003b98"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.572Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.572Z"),
"shard_location_id" : NumberLong(83981351)
},
{
"_id" : ObjectId("56b8806df5417242647b23cb"),
"user_id" : ObjectId("55ed6cfdb3b852c812003722"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.630Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.630Z"),
"shard_location_id" : NumberLong(68552635)
},
{
"_id" : ObjectId("56b8806df5417242647b23cc"),
"user_id" : ObjectId("55ed6cffb3b852c812003894"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.748Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.748Z"),
"shard_location_id" : NumberLong(80433985)
},
{
"_id" : ObjectId("56b8806df5417242647b23cd"),
"user_id" : ObjectId("55ed6cfbb3b852c8120035ed"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:57.957Z"),
"date_updated" : ISODate("2016-02-08T11:47:57.957Z"),
"shard_location_id" : NumberLong(67251008)
},
{
"_id" : ObjectId("56b8806ef5417242647b23ce"),
"user_id" : ObjectId("55ed6d01b3b852c812003a52"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:58.029Z"),
"date_updated" : ISODate("2016-02-08T11:47:58.029Z"),
"shard_location_id" : NumberLong(98099161)
},
{
"_id" : ObjectId("56b8806ef5417242647b23cf"),
"user_id" : ObjectId("55ed6d01b3b852c812003a7d"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:58.106Z"),
"date_updated" : ISODate("2016-02-08T11:47:58.106Z"),
"shard_location_id" : NumberLong(87539171)
},
{
"_id" : ObjectId("56b8806ef5417242647b23d0"),
"user_id" : ObjectId("55ed6cffb3b852c81200391d"),
"type" : NumberLong(1),
"status" : "approved",
"date_created" : ISODate("2016-02-08T11:47:58.229Z"),
"date_updated" : ISODate("2016-02-08T11:47:58.229Z"),
"shard_location_id" : NumberLong(78085842)
}
],
"media" : [ ],
"template_id" : ObjectId("5626c6c3b3b852bc31007ad6"),
"title_en" : "3D Modeling I",
"group_id" : ObjectId("563cc6993764872c268b45d5"),
"user_slots" : [
"15:30"
],
"date_start" : ISODate("2016-02-07T20:00:00Z"),
"date_finish" : ISODate("2016-03-05T20:00:00Z"),
"place_id" : null,
"points" : null,
"date_created" : ISODate("2015-11-06T15:26:17.468Z"),
"date_updated" : ISODate("2016-02-17T14:01:07.769Z"),
"shard_location_id" : NumberLong(84354891),
"shifted" : 5,
"title_hy" : "3D մոդելավորում I",
"public_access" : "0",
"location_access" : [
NumberLong(0)
],
"description_hy" : "",
"description_en" : "",
"min_age_access" : "",
"max_age_access" : "",
"max_users" : ""
}