何为工程，工匠的精神，系统的过程 - 看PostgreSQL解决fsync bug
何为工程，工匠的精神，系统的过程
Topic
Database
A collection of 7 issues
云游周报分享第2期
有些链接可能需要翻墙 这周恰逢美国的Martin Luther King Day，AVC分享了MLK说过的一句话，molder这个词传神: A genuine leader is not a searcher for consensus but a molder of consensus Martin Luther King Jr. Slack换了Logo – 上周的新闻忘发了。官博的解释主要是为了应对更多的场景。不过个人感觉是一次倒退，从灵动到平庸，缺少了个性化和playful的元素。 Github 2009和2019年的界面 – 整体布局没有太大的变化，2009年的界面有些还是当年Mac系统自带的Aqua风格组件，而到了2019年，所有的组件外观都被定制化了。 Web Authentication – Auth0做了一个页面演示了Web App如何通过Authenticator(比如Yubikey)做强用户验证。目前该标准在W3C草案阶段，新版本的浏览器已经支持了其中部分功能。 Macintosh 35周年
What Is a Data Model
Structure of the data Relational Model: Resembles an array of structs in C. Semistructured Model: XML Operations on the data Relational Model: Relational algebra (SQL) Semistructured Model: Path (e.g. n1.n2.n3.n4) Constraints Don’t see any major difference here. The semistructured model can say one element must
Connections and Sessions
Connection: A connection is a “physical circuit”, a pathway to a database server. Session: The SQL operations that are performed while a connection is active form a session. The session is associated with CATALOG(database) and SCHEMA. A connection can contain 0, 1 or more sessions
Notes for ARIES
Paper: ARIES: a transaction recovery method supporting fine-granularity locking and partial rollbacks using write-ahead logging Redo: LSN makes sure undo is performed only once. No additional log is written during redo process. Undo: LSN and CLR(Compensation log record) together makes sure undo is performed only once. CLR is written
Latches and Locks From ARIES
Difference between latches and locks Usually, latches are used to guarantee physical consistency of data, while locks are used to assure logical consistency of data. Hierarchical locking The intention locks (IX, IS, and SIX) are generally obtained on the higher levels of the hierarchy (e.g., table), and the S
Lessons Summarized by Michael Stonebraker
Paper: What goes around comes around IMS Era Physical and logical data independence are highly desirable Tree structured data models are very restrictive It is a challenge to provide sophisticated logical reorganizations of tree structured data A record-at-a-time user interface forces the programmer to do manual query optimization, and this