As is known, database schema is a collection of database rules like data type and data relationship. However, this is still a little abstract. So what is database schema in one sentence everyone could understand it clearly. The wikipedia page on Database schema is quite good for understanding the concept. A database schema of a…
How to find which package can be installed for a file, like “yum provides”? That is, the package is not installed yet and I do not know the package for a file that I want. The apt-file tool can do the similar things as yum provides. You may need to install it first by sudo…
I have a “t_form” table and a “t_attribute” table. It looks a little bit like below. Form table form_id | form_name | description ———————————– 1 | Laptop | Possible attributes are Model, Screen Size, OS, Cd Player 2 | Mobile | Possible attributes are Model, OS 3 | Tablet | Possible attributes are Model, Screen…
I have seen the question Better way to count total page views? I think, the better way is.. We can save the number of page views in the database. It is acceptable. But, it is not fulfilling my requirement, if many different users can appear to have the same IP Address (e.g, if they are…
How to reset the Disqus WordPress plugin installation? After deactivating/activating the Disqus WordPress plugin, the ID and others are the same as the old ones. What I need is to change the Disqus forum ID for a WordPress installation. Find all the tuples in the _option table of WordPress that contains “disqus” and delete them….
How to find out and change the storage engine of tables in MySQL databases? Find out the storage engine of a table in a database: SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = ‘database’ AND TABLE_NAME = ‘table’ Change the storage engine of a table: ALTER TABLE table ENGINE = type type can be innodb or…
How to repair tables database by backup Is this possible? Please explain how to repair. and thanks This post may help: https://www.systutorials.com/qa/300/how-to-repair-a-mysql-table thanks dear Zhiqiang Ma
Facebook uses lots MySQL databases. Any information about how Facebook scales MySQL? Some information on the Web: MySQL at Facebook’s page https://www.facebook.com/MySQLatFacebook?filter=1 A post by Ryan Thiessen, Database Operations at Facebook on Quora: http://www.quora.com/Facebook-Engineering/How-does-Facebook-structure-MySQL-so-that-it-is-robust-and-scalable And more: http://mashable.com/2011/12/15/facebook-timeline-mysql/ http://gigaom.com/2011/12/06/facebook-shares-some-secrets-on-making-mysql-scale/ http://www.wired.com/wiredenterprise/2011/12/facebook-timeline-anatomy “A lot of people are surprised that for this shiny new thing for Facebook, we’re using…
About caching system at Facebook. According to: https://www.facebook.com/notes/facebook-engineering/monitoring-cache-with-claspin/10151076705703920 Facebook has two major cache systems: Memcache, which is a simple lookaside cache with most of its smarts in the client, and TAO, a caching graph database that does its own queries to MySQL. The NSDI’13 paper introduces more about Memcache: https://www.usenix.org/conference/nsdi13/scaling-memcache-facebook The USENIX ATC’13 paper introduces…
After a server crash and restarting, MyBB reports a SQL Error as follows: MyBB SQL Error MyBB has experienced an internal SQL error and cannot continue. SQL Error: 145 – Table ‘./mybb/mybb_sessions’ is marked as crashed and should be repaired Query: SELECT * FROM mybb_sessions WHERE sid=’40021925bd0494ea31…’ AND ip=’x.x.x.x’ LIMIT 1 The dababase is MySQL….
Which tools to mange OCaml packages in my system (Linux)? I use OPAM to manage OCaml packages: http://opam.ocamlpro.com/index.html To install it: $ wget https://raw.githubusercontent.com/ocaml/opam/master/shell/opam_installer.sh $ sh ./opam_installer.sh /usr/local/bin More options are available here. To make opam settings take effect, append this to ~/.bashrc: eval `opam config env` Some frequent usages: opam list # List all…
Which are the consistency models used for distributed systems? Papers that survey the consistency models Robert C. Steinke and Gary J. Nutt. 2004. A unified theory of shared memory consistency. J. ACM 51, 5 (September 2004), 800-849. DOI=10.1145/1017460.1017464 http://doi.acm.org/10.1145/1017460.1017464 David Mosberger. 1993. Memory consistency models. SIGOPS Oper. Syst. Rev. 27, 1 (January 1993), 18-26. DOI=10.1145/160551.160553…
What are the popular / good NoSQL databases nowadays? MongoDB, CouchDB Find more at https://en.wikipedia.org/wiki/NoSQL and http://nosql-database.org/ Answered by omshivaprakash.
What are the SQL layer solution over NoSQL databases such as key/value stores? Phoenix: A SQL layer on HBase: https://github.com/forcedotcom/phoenix They also show some performance results: https://github.com/forcedotcom/phoenix/wiki/Performance F1 – The Fault-Tolerant Distributed RDBMS Supporting Google’s Ad Business: http://research.google.com/pubs/pub38125.html With F1, we have built a novel hybrid system that combines the scalability, fault tolerance, transparent sharding,…
How to enable single sign-in for social accounts for question2answer? These servers are required: Google, Facebook, Twitter, OpenID. This site moved from Loginza to Question2Answer Open Login which works like a charm. I use the Loginza and it works very well. For Q2A, SLonoed wrote a nice plugin for loginza. How to use it: Download…
This blog will explain about how to add a custom content in a Receipt which will be generated from MPOS in Microsoft Dynamics. Microsoft provides us with certain fields which can be put into the receipt. There are certain fields which a client will ask to show in the receipt. If the desired field is…
Technology Hibernate Envers is the frameworks for auditing entities. As the name suggests Hibernate Envers is developed on top of Hibernate, it will on Hibernate and Hibernate implemented JPA. Hibernate Envers provides easy auditing, versioning solution for entity classes. Advantages of Hibernate Envers: Auditing of all mappings defined by JPA specification. Auditing Hibernate specific mappings…
Introduction In this tutorial, we will be learning as how to deploy .NET Core 2.0 MVC web application on Microsoft Public Cloud i.e. Microsoft Azure, using Microsoft Visual Studio 2017 v15.3 For novice Cloud developers, aspiring .NET / Cloud architects, and all other IT professionals associated with the .NET Core framework & Cloud computing, especially…
Solution is very important part of Dynamics CRM. In order to deploy your customization, solution is the only bridge which help you to achieve your goal. There are two types of solutions available in CRM: Managed and Unmanaged. Managed Solutions: This is the solutions that you can import and publish only. You neither export it nor you can…
WordPress can be very fast after some effort on performance optimization with the help from its plenty of plugins. Possible ways include using cache to cut down the number of database queries, improves HTML/JavaScript/CSS code, and optimizing PHP’s performance with opcode cache. In this post, we introduce how to speed up WordPress with OPcache, page…