The New York State Identification and Intelligence System Phonetic Code, commonly known as NYSIIS, is a phonetic algorithm devised in 1970 as part of the New York State Identification and Intelligence System (now a part of the New York State Division of Criminal Justice Services). It features an accuracy increase of 2.7% over the traditional Soundex algorithm.
Metaphone is a phonetic algorithm, published by Lawrence Philips in 1990, for indexing words by their English pronunciation. It fundamentally improves on the Soundex algorithm by using information about variations and inconsistencies in English spelling and pronunciation to produce a more accurate encoding, which does a better job of matching words and names which sound similar. As with Soundex, similar-sounding words should share the same keys. Metaphone is available as a built-in operator in a number of systems.
Instruction: Given an input question, respond with syntactically correct PostgreSQL. Be creative but the SQL must be correct. Only use tables called "users" and "charges". The "users" table has columns: id (integer), signup_dt (timestamp), email (character varying), and plan_type (character varying). The "charges" table has columns: amount (bigint), user_id (integer), and charge_dt (timestamp).
Input: how much revenue did we have in the past 7 days?
然後輸出了：
GPT-3 Response: SELECT SUM(amount) FROM charges WHERE charge_dt > now() - interval '7 days'
接下來是在同樣 instruction 下，跨表格的問題：
Input: how much revenue have we had from users that signed up in the last 6 months?
這時候 INNER JOIN 就跑出來了：
.8 Temperature GPT-3 Response: SELECT SUM(charges.amount) FROM users INNER JOIN charges ON users.id = charges.user_id WHERE signup_dt >= DATE_SUB(now(), INTERVAL '6 months')
後面的問題也很精彩，看起來之後可以接上 BI dashboard，直接丟句子進去，然後拉各種資料出來視覺化？
看起來是 2019 年年初的時候 MySQL 5.1 出問題，後續決定安排升級，在 2019 年年中把系統升級到 MySQL 5.7 (Percona Server 版本)：
Our first major hurdle was to get current with our version of MySQL. In July, 2019 we completed the MySQL 5.1 to MySQL 5.7 (v5.7.19-17-log Percona Server to be precise) upgrade across all MySQL instances.
Not only was support for MySQL 5.1 at End-of-Life (more than 5 years ago) but our MySQL 5.1 instances on EC2/AWS had limited storage and we were scheduled to run out of space at the end of July. Our backs were up against the wall and we had to deliver!
另外在升級到 5.7 的時候，順便把本來是 INT 的 primary key 都換成 BIGINT：
As part of the cut-over to MySQL 5.7, we also took the opportunity to bake in a number of improvements. We converted all primary key columns from INT to BIGINT to prevent hitting MAX value.
In parallel with the MySQL 5.7 upgrade we also Upgraded Django to 1.6 due a behavioral change in MySQL 5.7 related to how transactions/commits were handled for SELECT statements. This behavior change was resulting in errors with older version of Python/Django running on MySQL 5.7
Eventbrite had traditionally used pt-online-schema-change (pt-osc) to ALTER MySQL tables in production. pt-osc uses MySQL triggers to move data from the original to the “duplicate” table which is a very expensive operation and can cause replication lag. Matter of fact, it had directly resulted in several outages in H1 of 2019 due to replication lag or breakage.
Next on the list was implementing improvements to MySQL high availability and automatic failover using Orchestrator. In February of 2020 we implemented a new HAProxy layer in front of all DB clusters and we released Orchestrator to production!
Orchestrator can successfully detect the primary failure and promote a new primary. The goal was to implement Orchestrator with HAProxy first and then eventually move to Orchestrator with ProxySQL.
然後最後題到了 Square 研發的 Shift，把 gh-ost 包裝起來變成有個 web UI 可以操作：
As with any database, fitting your data into RAM will allow for faster reads than from disk. MongoDB is no different. Knowing how much data MongoDB has to read in for your queries can help you determine how much RAM you should allocate to your database.
這樣的設計邏輯很奇怪啊，你不要扯其他 database 啊，你們家主力的 InnoDB 一直都沒有推薦要 Working Set < RAM 啊，反過來才是用 InnoDB 的常態吧，而且在 PostgreSQL 上也是這樣吧 XDDD
回到原來的文章，裡面提到了 core team 的不成文規定，這個部份可以從 Contributor Profiles 這邊看到目前 core team 有五位成員，Peter Eisentraut 來自 2ndQuadrant，而 Bruce Momjian (這是文章作者自己) 與 Dave Page 則是來自 EnterpriseDB：
First, there is an unwritten rule that the Postgres core team should not have over half of its members from a single company, and the acquisition causes edb's representation in the core team to be 60% — the core team is working on a solution for this.
Whether PostgreSQL’s repeatable-read behavior is correct therefore depends on one’s interpretation of the standard. It is surprising that a database based on snapshot isolation would reject the strict interpretation chosen by the seminal paper on SI, but on reflection, the behavior is defensible.
The execution of concurrent SQL-transactions at isolation level SERIALIZABLE is guaranteed to be serializable. A serializable execution is defined to be an execution of the operations of concurrently executing SQL-transactions that produces the same effect as some serial execution of those same SQL-transactions. A serial execution is one in which each SQL-transaction executes to completion before the next SQL-transaction begins.
