Create Trigger Mysql

As the most popular open source database, MySQL is widely used in Web applications and other small and medium-sized projects. However, in many large IT companies, MySQL has gradually deviated from the original open source version after being highly optimized and customized, more like a branch, such as the Webscalesql of Facebook, which was not long ago open source. 　　Recently, Mr. Xiong has published a blog post, from the perspective of large-scale web site architecture development of the changes in MySQL application, here for you to share. This article mainly describes the different and ...

MySQL database sql statement commonly used optimization methods 1. Query optimization, should try to avoid full table scan, should first consider where and order by the columns involved in the establishment of the index. 2. Should be avoided in the where clause on the field null value judgment, otherwise it will cause the engine to abandon the use of indexes and full table scan, such as: select id from t where num is null You can set the default value of num 0, to ensure that Num column table does not null value ...

Overview 2.1.1 Why a Workflow Dispatching System A complete data analysis system is usually composed of a large number of task units: shell scripts, java programs, mapreduce programs, hive scripts, etc. There is a time-dependent contextual dependency between task units In order to organize such a complex execution plan well, a workflow scheduling system is needed to schedule execution; for example, we might have a requirement that a business system produce 20G raw data a day and we process it every day, Processing steps are as follows: ...

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Overview How to deal with high concurrency, large traffic? How to ensure data security and database throughput? How do I make data table changes under massive data? Doubanfs and DOUBANDB characteristics and technology implementation? During the QConBeijing2009, the Infoq Chinese station was fortunate enough to interview Hong Qiangning and discuss related topics. Personal Profile Hong Qiangning, graduated from Tsinghua University in 2002, is currently the chief architect of Beijing Watercress Interactive Technology Co., Ltd. Hong Qiangning and his technical team are committed to using technology to improve people's culture and quality of life ...

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Foreign key role: Maintain data consistency, integrity, the main purpose is to control the data stored in the foreign key table. So that the two forms related, the foreign key can only refer to the value of the column in the surface! For example: ab two tables a table has the customer number, customer name b table stored in each customer's order After the foreign key You can only delete clients in Table a if you do not have Customer x in the b table. Prerequisites: The columns in this table must be the same as the foreign keys (the foreign key must be a foreign key). Specify ...

In the use of Team collaboration tool Worktile, you will notice whether the message is in the upper-right corner, drag the task in the Task panel, and the user's online status is refreshed in real time. Worktile in the push service is based on the XMPP protocol, Erlang language implementation of the Ejabberd, and on its source code based on the combination of our business, the source code has been modified to fit our own needs. In addition, based on the AMQP protocol can also be used as a real-time message to push a choice, kick the net is to use rabbitmq+ ...

Large data will challenge the enterprise's storage architecture and data center infrastructure, and will trigger the ripple effect of cloud computing, data Warehouse, data mining, business intelligence and so on. In 2011, companies will use more TB (1TB=1000GB) Datasets for business intelligence and Business Analytics, and by 2020 global data usage is expected to rise 44 times-fold to 35.2ZB (1zb=10 billion TB). The challenges of large data for the vast number of data information, how the complex application of these data into the current data warehousing, business intelligence and data analysis technology ...

Note: This article starts in CSDN, reprint please indicate the source. "Editor's note" in this article for the online Office platform Gleasy co-founder, technical team boss Shike wrote, he gave us to share the gleasy all the way to the technical combat. It is reported that the release of nearly three years of Gleasy, has successfully accumulated more than 50,000 enterprise users, in response to mass storage and high concurrency under the premise of a variety of basic problems in the solution of deep experience. At the same time, March 18, 2015, Gleasy will officially release the 3.0 edition "about", and the introduction of English version, complex ...