文章目錄

• 概述
• 官方說明
• 示例
• Percentiles優化 compression

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概述

繼續跟中華石杉老師學習ES，第48篇

課程地址： https://www.roncoo.com/view/55

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官方說明

Percentiles Aggregation： 戳這里

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示例

需求： 網站訪問時延統計

為了演示該功能，我們先建個索引，模擬一批數據

#新建索引 PUT /website {"mappings": {"logs": {"properties": {"latency": {"type": "long"},"province": {"type": "keyword"},"timestamp": {"type": "date"}}}} } #模擬數據 POST /website/logs/_bulk { "index": {}} { "latency" : 105, "province" : "江蘇", "timestamp" : "2018-10-28" } { "index": {}} { "latency" : 83, "province" : "江蘇", "timestamp" : "2018-10-29" } { "index": {}} { "latency" : 92, "province" : "江蘇", "timestamp" : "2018-10-29" } { "index": {}} { "latency" : 112, "province" : "江蘇", "timestamp" : "2018-10-28" } { "index": {}} { "latency" : 68, "province" : "江蘇", "timestamp" : "2018-10-28" } { "index": {}} { "latency" : 76, "province" : "江蘇", "timestamp" : "2018-10-29" } { "index": {}} { "latency" : 101, "province" : "新疆", "timestamp" : "2018-10-28" } { "index": {}} { "latency" : 275, "province" : "新疆", "timestamp" : "2018-10-29" } { "index": {}} { "latency" : 166, "province" : "新疆", "timestamp" : "2018-10-29" } { "index": {}} { "latency" : 654, "province" : "新疆", "timestamp" : "2018-10-28" } { "index": {}} { "latency" : 389, "province" : "新疆", "timestamp" : "2018-10-28" } { "index": {}} { "latency" : 302, "province" : "新疆", "timestamp" : "2018-10-29" }

DSL:

#網站訪問時延統計（50% 95% 99%的請求） GET /website/logs/_search {"size": 0,"aggs": {"latency_percentiles": {"percentiles": {"field": "latency","percents": [50,95,99]}},"latency_avg": {"avg": {"field": "latency"}}} }

返回：

{"took": 3,"timed_out": false,"_shards": {"total": 5,"successful": 5,"skipped": 0,"failed": 0},"hits": {"total": 12,"max_score": 0,"hits": []},"aggregations": {"latency_avg": {"value": 201.91666666666666},"latency_percentiles": {"values": {"50.0": 108.5,"95.0": 627.4999999999997,"99.0": 654}}} }

可知,

• 50%的請求 在 108.5毫秒
• 95%的請求 在 627.5毫秒
• 99%的請求 在 654毫秒
• 平均時延 201.9毫秒

數值的最大的值是多少，不是完全準確的

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需求二：按地區分組后看下每個地區的 網站訪問時延統計

GET /website/_search {"size": 0,"aggs": {"group_by_province": {"terms": {"field": "province"},"aggs": {"latency_percentiles": {"percentiles": {"field": "latency","percents": [50,95,99]}},"latency_avg": {"avg": {"field": "latency"}}}}} }

返回：

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Percentiles優化 compression

compression 官方指導： 戳這里

TDigest算法，用很多節點來執行百分比的計算，近似估計，有誤差，節點越多，越精準

compression ，限制節點數量最多 compression * 20 = 2000個node去計算 ，默認100

compression 越大，占用內存越多，越精準，性能越差

一個節點占用32字節，100 * 20 * 32 = 64KB

簡單來說： 如果你想要percentile算法越精準，compression可以設置的越大

總結

以上是生活随笔為你收集整理的白话Elasticsearch48-深入聚合数据分析之 Percentiles Aggregation-percentiles百分比算法以及网站访问时延统计及Percentiles优化的全部內容，希望文章能夠幫你解決所遇到的問題。

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