May 2019
Intermediate to advanced
464 pages
9h 22m
Japanese
Content preview from Node.jsデザインパターン 第2版
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304
9
章 特殊な問題を解決するためのパターン
9.2
非同期のバッチ処理とキャッシュの利用
高負荷のアプリケーションでは「キャッシュ」が非常に重要な役割を担い、ウェブページ、画像、ス
タイルシートといった静的なリソースからデータベースへのクエリの結果といったデータまで、さまざ
まなものがキャッシングの対象になります。この節では、非同期処理とキャッシングとの関係やその性
能向上の度合いについて説明します。
9.2.1
キャッシュ処理もバッチ処理もないサーバの実装
この新しい難題に取り組む前に、これから実装するさまざまな技法の効果を測定する基準として使
うための小さなデモサーバを実装しておきましょう。
電子商取引を行う会社の販売管理をするウェブサーバを考えます。具体的課題として、サーバに対
するクエリで、特定のタイプの商品に関する売上の合計を問い合わせたいとしましょう。この目的のた
め、ここでも簡便さと柔軟性を兼ね備えた
LevelUP
を使います。使用するデー
タモデルは、
sales
と
いうサブレベル（データベースのセクション）に保存されたトランザクションの単なるリストです。次の
形式で構成されています。
transactionId {amount, item}
キーは
transactionId
（トランザクション
ID
）になっており、値は
JSON
オブジェクトで
amount
（金
額）と
item
（商品のタイプ）が入っています。
処理するデータはきわめて基本的なものですから、
totalSales.js
という名前のファイ
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.