如何使用Scala将1亿条记录加载到MongoDB中进行性能测试？

Question

我有一个用Scala编写的小脚本,用于加载具有100,000,000个样本记录的MongoDB实例.我们的想法是让数据库全部加载,然后进行一些性能测试(并在必要时调整/重新加载).

问题是每100,000个记录的加载时间相当线性增加.在我的加载过程开始时,只需4秒即可加载这些记录.现在,在接近6,000,000条记录中,加载相同数量(100,000)需要300到400秒!那要慢两个数量级!查询仍然很快,但按照这个速度,我永远无法加载我想要的数据量.

如果我用我的所有记录(全部100,000,000!)编写一个文件,然后使用mongoimport导入整个文件,这会更快吗？或者我的期望是否过高而且我使用的数据库超出了应该处理的范围？

有什么想法吗？谢谢!

这是我的脚本:

import java.util.Date

import com.mongodb.casbah.Imports._
import com.mongodb.casbah.commons.MongoDBObject

object MongoPopulateTest {
  val ONE_HUNDRED_THOUSAND = 100000
  val ONE_MILLION          = ONE_HUNDRED_THOUSAND * 10

  val random     = new scala.util.Random(12345)
  val connection = MongoConnection()
  val db         = connection("mongoVolumeTest")
  val collection = db("testData")

  val INDEX_KEYS = List("A", "G", "E", "F")

  def main(args: Array[String]) {
    populateCoacs(ONE_MILLION * 100)
  }

  def populateCoacs(count: Int) {
    println("Creating indexes: " + INDEX_KEYS.mkString(", "))
    INDEX_KEYS.map(key => collection.ensureIndex(MongoDBObject(key -> 1)))

    println("Adding " + count + " records to DB.")

    val start     = (new Date()).getTime()
    var lastBatch = start

    for(i <- 0 until count) {
      collection.save(makeCoac())
      if(i % 100000 == 0 && i != 0) {
        println(i + ": " + (((new Date()).getTime() - lastBatch) / 1000.0) + " seconds (" +  (new Date()).toString() + ")")
        lastBatch = (new Date()).getTime()
      }
    }

    val elapsedSeconds = ((new Date).getTime() - start) / 1000

    println("Done. " + count + " COAC rows inserted in " + elapsedSeconds + " seconds.")
  }

  def makeCoac(): MongoDBObject = {
    MongoDBObject(
      "A" -> random.nextPrintableChar().toString(),
      "B" -> scala.math.abs(random.nextInt()),
      "C" -> makeRandomPrintableString(50),
      "D" -> (if(random.nextBoolean()) { "Cd" } else { "Cc" }),
      "E" -> makeRandomPrintableString(15),
      "F" -> makeRandomPrintableString(15),
      "G" -> scala.math.abs(random.nextInt()),
      "H" -> random.nextBoolean(),
      "I" -> (if(random.nextBoolean()) { 41 } else { 31 }),
      "J" -> (if(random.nextBoolean()) { "A" } else { "B" }),
      "K" -> random.nextFloat(),
      "L" -> makeRandomPrintableString(15),
      "M" -> makeRandomPrintableString(15),
      "N" -> scala.math.abs(random.nextInt()),
      "O" -> random.nextFloat(),
      "P" -> (if(random.nextBoolean()) { "USD" } else { "GBP" }),
      "Q" -> (if(random.nextBoolean()) { "PROCESSED" } else { "UNPROCESSED" }),
      "R" -> scala.math.abs(random.nextInt())
    )
  }

  def makeRandomPrintableString(length: Int): String = {
    var result = ""
    for(i <- 0 until length) {
      result += random.nextPrintableChar().toString()
    }
    result
  }
}

这是我脚本的输出:

Creating indexes: A, G, E, F
Adding 100000000 records to DB.
100000: 4.456 seconds (Thu Jul 21 15:18:57 EDT 2011)
200000: 4.155 seconds (Thu Jul 21 15:19:01 EDT 2011)
300000: 4.284 seconds (Thu Jul 21 15:19:05 EDT 2011)
400000: 4.32 seconds (Thu Jul 21 15:19:10 EDT 2011)
500000: 4.597 seconds (Thu Jul 21 15:19:14 EDT 2011)
600000: 4.412 seconds (Thu Jul 21 15:19:19 EDT 2011)
700000: 4.435 seconds (Thu Jul 21 15:19:23 EDT 2011)
800000: 5.919 seconds (Thu Jul 21 15:19:29 EDT 2011)
900000: 4.517 seconds (Thu Jul 21 15:19:33 EDT 2011)
1000000: 4.483 seconds (Thu Jul 21 15:19:38 EDT 2011)
1100000: 4.78 seconds (Thu Jul 21 15:19:43 EDT 2011)
1200000: 9.643 seconds (Thu Jul 21 15:19:52 EDT 2011)
1300000: 25.479 seconds (Thu Jul 21 15:20:18 EDT 2011)
1400000: 30.028 seconds (Thu Jul 21 15:20:48 EDT 2011)
1500000: 24.531 seconds (Thu Jul 21 15:21:12 EDT 2011)
1600000: 18.562 seconds (Thu Jul 21 15:21:31 EDT 2011)
1700000: 28.48 seconds (Thu Jul 21 15:21:59 EDT 2011)
1800000: 29.127 seconds (Thu Jul 21 15:22:29 EDT 2011)
1900000: 25.814 seconds (Thu Jul 21 15:22:54 EDT 2011)
2000000: 16.658 seconds (Thu Jul 21 15:23:11 EDT 2011)
2100000: 24.564 seconds (Thu Jul 21 15:23:36 EDT 2011)
2200000: 32.542 seconds (Thu Jul 21 15:24:08 EDT 2011)
2300000: 30.378 seconds (Thu Jul 21 15:24:39 EDT 2011)
2400000: 21.188 seconds (Thu Jul 21 15:25:00 EDT 2011)
2500000: 23.923 seconds (Thu Jul 21 15:25:24 EDT 2011)
2600000: 46.077 seconds (Thu Jul 21 15:26:10 EDT 2011)
2700000: 104.434 seconds (Thu Jul 21 15:27:54 EDT 2011)
2800000: 23.344 seconds (Thu Jul 21 15:28:17 EDT 2011)
2900000: 17.206 seconds (Thu Jul 21 15:28:35 EDT 2011)
3000000: 19.15 seconds (Thu Jul 21 15:28:54 EDT 2011)
3100000: 14.488 seconds (Thu Jul 21 15:29:08 EDT 2011)
3200000: 20.916 seconds (Thu Jul 21 15:29:29 EDT 2011)
3300000: 69.93 seconds (Thu Jul 21 15:30:39 EDT 2011)
3400000: 81.178 seconds (Thu Jul 21 15:32:00 EDT 2011)
3500000: 93.058 seconds (Thu Jul 21 15:33:33 EDT 2011)
3600000: 168.613 seconds (Thu Jul 21 15:36:22 EDT 2011)
3700000: 189.917 seconds (Thu Jul 21 15:39:32 EDT 2011)
3800000: 200.971 seconds (Thu Jul 21 15:42:53 EDT 2011)
3900000: 207.728 seconds (Thu Jul 21 15:46:21 EDT 2011)
4000000: 213.778 seconds (Thu Jul 21 15:49:54 EDT 2011)
4100000: 219.32 seconds (Thu Jul 21 15:53:34 EDT 2011)
4200000: 241.545 seconds (Thu Jul 21 15:57:35 EDT 2011)
4300000: 193.555 seconds (Thu Jul 21 16:00:49 EDT 2011)
4400000: 190.949 seconds (Thu Jul 21 16:04:00 EDT 2011)
4500000: 184.433 seconds (Thu Jul 21 16:07:04 EDT 2011)
4600000: 231.709 seconds (Thu Jul 21 16:10:56 EDT 2011)
4700000: 243.0 seconds (Thu Jul 21 16:14:59 EDT 2011)
4800000: 310.156 seconds (Thu Jul 21 16:20:09 EDT 2011)
4900000: 318.421 seconds (Thu Jul 21 16:25:28 EDT 2011)
5000000: 378.112 seconds (Thu Jul 21 16:31:46 EDT 2011)
5100000: 265.648 seconds (Thu Jul 21 16:36:11 EDT 2011)
5200000: 295.086 seconds (Thu Jul 21 16:41:06 EDT 2011)
5300000: 297.678 seconds (Thu Jul 21 16:46:04 EDT 2011)
5400000: 329.256 seconds (Thu Jul 21 16:51:33 EDT 2011)
5500000: 336.571 seconds (Thu Jul 21 16:57:10 EDT 2011)
5600000: 398.64 seconds (Thu Jul 21 17:03:49 EDT 2011)
5700000: 351.158 seconds (Thu Jul 21 17:09:40 EDT 2011)
5800000: 410.561 seconds (Thu Jul 21 17:16:30 EDT 2011)
5900000: 689.369 seconds (Thu Jul 21 17:28:00 EDT 2011)

Answer 1

一些技巧 :

1. 在插入之前不要索引您的集合,因为插入会修改索引,这是一个开销.插入所有内容,然后创建索引.

2. 而不是"保存",使用mongoDB"batchinsert",它可以在1次操作中插入许多记录.因此,每批插入约5000个文档.您将看到显着的性能提升.

   在这里看到插入的方法#2 ,它需要插入文件数组而不是单个文件.另请参阅此主题中的讨论

   如果你想要更多的基准 -

3. 这只是猜测,尝试使用预定义大尺寸的上限集合来存储您的所有数据.没有索引的上限集合具有非常好的插入性能.

Answer 2

我有同样的事情.据我所知,它归结为索引值的随机性.每当插入新文档时,显然还需要更新所有基础索引.因为您将随机值(而不是顺序值)插入到这些索引中,所以您不断访问整个索引以查找新值的放置位置.

当所有索引都快乐地放在内存中时,这一切都很好,但是一旦它们变得太大,你需要开始点击磁盘来执行索引插入,然后磁盘开始抖动并写入性能死亡.

在加载数据时,尝试db.collection.totalIndexSize()与可用内存进行比较,您可能会发现这种情况.

最好的办法是在加载数据后创建索引.但是,当它是包含随机值(GUID,哈希等)的必需_id索引时,这仍然无法解决问题,那么您最好的方法可能是考虑分片或获取更多RAM.