Updating one table from another
SQL (pronounced "ess-que-el") stands for Structured Query Language. According to ANSI (American National Standards Institute), it is the standard language for relational database management systems.SQL statements are used to perform tasks such as update data on a database, or retrieve data from a database.95th percentile updates available in this service within 5 sec, and max 10 sec). So the new service just goes directly to the source tables to get the data it needs to fulfill its requests.Breaking these SLAs should result in humans being alerted. ) example, let’s say we work at Twitter, and this new service provides read access to comprised of various user profile fields that users can edit, along with summary counts of various things related to the user. Many existing services that generate lots of revenue are implemented like this, and if this approach meets all requirements, then great!
This tutorial will provide you with the instruction on the basics of each of these commands as well as allow you to put them to practice using the SQL Interpreter.
Imagine that we are asked to build a new service that provides a single point of read access to data from multiple sources within our company.
Data is created and updated by those other sources, not this new service.
To provide business value, this new service needs to be low latency, providing very fast response times under non-trivial load (e.g.
95th percentile HTTP response time under 5 msec, and max 10 msec, at 1000 HTTP requests/sec).
To improve performance, these services often pre-compute materialized views and store them in caches.