NoSQL產(chǎn)品越來越火,NoSQL產(chǎn)品通常以其高性能,強擴展性和高容錯性為大家所稱道,我們在問為什么NoSQL會流行起來的時候,或許應(yīng)該問一下為什么這些功能會變得這么重要.

• We’re dealing with much more data. Although advances in storage capacity and CPU speed have allowed the databases to keep pace, we’re in a new era where size itself is an important part of the problem, and any significant database needs to be distributed.

• 由于我們需要處理的數(shù)據(jù)集越來越大,其存儲量已經(jīng)遠(yuǎn)遠(yuǎn)超過了單機的容量,數(shù)據(jù)處理的需求也遠(yuǎn)遠(yuǎn)超過了單機CPU的運算能力.所以我們需要分布式的辦理方案.

• We require sub-second responses to queries. In the ’80s, most database queries could run overnight as batch jobs. That’s no longer acceptable. While some analytic functions can still run as overnight batch jobs, we’ve seen the web evolve from static files to complex database-backed sites, and that requires sub-second response times for most queries.

• 我們對數(shù)據(jù)提供速度的要求越來越高,在80年代,可能很多運算都需要跑一整晚.但是這種事情放在現(xiàn)在就變得不可接受了.對于復(fù)雜的統(tǒng)計分析我們可以忍受,但是對于網(wǎng)站應(yīng)用來說,快速響應(yīng)是必須的.

• We want applications to be up 24/7. Setting up redundant servers for static HTML files is easy, but a database replication in a complex database-backed application is another.

• 我們需要提供7×24的服務(wù).如果你的網(wǎng)站只有一個靜態(tài)頁,那估計問題不大,只需要做好WebServer的容錯性就行了.而如果你是一個背后有數(shù)據(jù)庫,有緩存的動態(tài)網(wǎng)站,那你就必須做好數(shù)據(jù)層的容錯及自動故障遷移.

• We’re seeing many applications in which the database has to soak up data as fast (or even much faster) than it processes queries: in a logging application, or a distributed sensor application, writes can be much more frequent than reads. Batch-oriented ETL (extract, transform, and load) hasn’t disappeared, and won’t, but capturing high-speed data flows is increasingly important.

• 很多應(yīng)用場景需要數(shù)據(jù)層提供更高的寫性能和數(shù)據(jù)吞吐.比如日志型應(yīng)用,對寫性能的要求可能非常高,當(dāng)寫性能成為瓶頸時,通常我們很難難過升級單機配置來辦理.所以分布式的需求在這里變得也很重要.

• We’re frequently dealing with changing data or with unstructured data. The data we collect, and how we use it, grows over time in unpredictable ways. Unstructured data isn’t a particularly new feature of the data landscape, since unstructured data has always existed, but we’re increasingly unwilling to force a structure on data a priority.

• 我們對非結(jié)構(gòu)化數(shù)據(jù)的存儲和處理需求日增,在這個變化的世界,互聯(lián)網(wǎng)領(lǐng)域的應(yīng)用可能越來越難像軟件開發(fā)一樣,去預(yù)先寫義各種數(shù)據(jù)結(jié)構(gòu).

• We’re willing to sacrifice our sacred cows. We know that consistency and isolation and other properties are very valuable, of course. But so are some other things, like latency and availability and not losing data even if our primary server goes down. The challenges of modern applications make us realize that sometimes we might need to weaken one of these constraints in order to achieve another.

• 我們的應(yīng)用場景對一致性,隔離性以及其它一些事務(wù)特性的需求可能越來越低,相反的,我們對性能,對擴展性的需求可能越來越高.于是在新的需求下,我們必須做出抉擇,放棄一些我們習(xí)慣了的優(yōu)秀功能,去獲取一些我們需要的新的特性.

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