Home » 2015 » July

Git 2.5 的 worktree

GitHubGit 2.5 寫的介紹:「Git 2.5, including multiple worktrees and triangular workflows」。

Please note that the worktree feature is experimental. It may have some bugs, and its interface may change based on user feedback. It's not recommended to use git worktree with a repository that contains submodules.


Git 2.5 includes performance improvements aimed at large working trees and working trees stored on networked filesystems (e.g., NFS):

Amazon Redshift 的 Data Ingestion

AWS 放出的「Amazon redshift migration and load data 20150722」這份投影片則是解釋了 data ingestion 時的建議行為。

其實這張就道盡目前 Amazon Redshift 架構上的最佳作法,也就是每次都 TRUNCATE 掉重新 import。後面的所有方法其實都是 workaround,效能不會太好... XD

另外後面是介紹倒資料進 Amazon Redshift 的方式,官方是還蠻推 AWS Data Pipeline,但你用過就會知道有多麻煩與痛苦...

Amazon Redshift 的效能調校

在「Amazon redshift optimizing performance 20150721」這篇給了不少效能調校的細節,這邊的效能調校都是針對多機器時的設計規劃 (multi nodes)。

本文圖多並且穿插大量文字,但應該是可以輕鬆讀。我從中選了重點投影片出來,在讀完這篇導讀後建議再點進去從頭讀一次,會對 Amazon Redshift 有更多了解。





接下來是講 sort keys 有三種,其中 interleaved 很特別,有興趣的可以研究看看,不然 compound keys 應該是已經很好用了:


然後原始資料可以儘量拆成多個檔案再匯入 Amazon Redshift,這樣可以加速進行:

最後則是 VACUUM 的操作介紹,如果可以允許完整 deep copy 的話會更好,因為這算是最乾淨的作法:

是份很有用的投影片 :p

Microsoft Windows 10 對 CDN 的影響

在「Microsoft's Windows 10 launch is going to strain CDNs, already passed 10 Tbps」這邊看到 Microsoft 推出 Windows 10 已經吃掉 10Tbps 的 capacity 了。

預定還會吃到 40Tbps,就當作八卦消息看一看好了:

Streaming Media is citing internal sources and is saying that Microsoft has reserved up to 40 Tbps with all of the key CDNs which is a massive amount of bandwidth. As of July 28th at 1PM ET, Microsoft is said to already be consuming over 10 Tbps and seeing that all regions are not yet online for deployment, it's only going to go higher.

是個熱鬧的祭典 XD

Backblaze 2015 年上半年的硬碟穩定度報告出爐了... (又黑了某公司一把)

Backblaze 這次丟出了 2015 年上半年的數據,標題雖然是寫 2015Q2,但文章裡有半年的統計資料:「Hard Drive Reliability Stats for Q2 2015」。

雖然都知道某公司的產品故障率偏高,但這樣是有仇嗎 XDDD


另外是 4TB 的歷史紀錄,右邊兩家的數字有點少啊,不過 45 顆硬碟壞一顆不就 2.x% 了嗎,這數字到底是怎麼出來的啊:

Amazon Aurora 宣佈正式開放

AWS 宣佈正式開放所有客戶使用 Amazon Aurora:「Now Available – Amazon Aurora」。不過也只是原來支援的三個地區而已:

Today I am happy to announce that Amazon Aurora is now available for use by all AWS customers, in three AWS regions.

We are launching in the US East (Northern Virginia), US West (Oregon), and Europe (Ireland) regions, and will expand to others over time.


When we first announced Amazon Aurora we expected to deliver a service that offered at least 4 times the price-performance of existing solutions. Now that we are ready to ship, I am happy to report that we’ve exceeded this goal, and that Amazon Aurora can deliver 5x the price-performance of a traditional relational database when run on the same class of hardware.

In general, this does not mean that individual queries will run 5x as fast as before (although Amazon Aurora’s fast, SSD-based storage certainly speeds things up). Instead, it means that Amazon Aurora is able to handle far more concurrent queries (both read and write) than other products. Amazon Aurora’s unique, highly parallelized access to storage reduces contention for stored data and allows it to process queries in a highly efficient fashion.


CNNIC 申請成為 CA/Browser Forum 成員

面對面的會議記錄,在第一天的會議記錄「2015-06-24 Face-to-Face Meeting 35 Minutes」的一開頭就看到 CNNIC 申請成為 CA/Browser Forum 的成員。


1. They don’t appear to be licensed in China (BRs requires that a CA be licensed in the country they do business if a licensing scheme is in place) and

第二個則是同時具有 CA 以及 ccTLD 註冊者的身份:

2. they appear to be a registrar for a TLD as well as a CA.

再來是第二天開頭就看到在討論 EV Wildcard 的問題 (目前是不被允許的),以及 Domain Validation 的問題。結尾則可以看到中華電信將會主辦 2017 的部份?不是很確定...

Host 2017

Chunghwa Telecom February or October (Taiwan)

Ubuntu 內建的 Noto Sans CJK...

今天在 Facebook 上才看到 chihchun 貼的資料,在 Ubuntu 14.04 之後都有 Noto Sans CJK 可以用:

sudo apt-get install fonts-noto-cjk #

Posted by 蔡志展 on Sunday, July 26, 2015

這邊提到的是 fonts-noto-cjk,不過我實際測試發現裝 fonts-noto 會比較好:前者預設值很細 (Light),後者包括了各種粗細 (我自己是用 DemiLight)。