postgresql merge rows into one

PostgreSQL is similar to Oracle's multi-process framework, so it can support high-concurrency application scenarios. This is similar to Oracle databases, so it is easier to switch Oracle DBA to PostgreSQL databases, after all, PostgreSQL databases

PostgreSQL Hardware Performance Tuning Translated from the article "PostgreSQL Hardware performance Tuning" PostgreSQL is an object-relational database developed by developers all over the world on the Internet. She is an open source

MySQL is so widely used that I have to migrate some applications from MySQL to PostgreSQL, many open source software is mysql as a database standard, and MySQL as the basis of the abstract, but the use of the process, found that MySQL has a lot of

Oracle and postgresql join methodFirst, we will introduce several oracle multi-Table Connection Methods:Nested loop: nested loop, which is actually a dual FOR LOOP1. The driver table (External table) and search table (internal table) are divided

Someone recently proposed to view the Postgresql execution plan. The following describes how the cost and other related values in the PG execution plan are calculated:PG version 9.1.21. Use the terminal tool PGADMIN to press F7 to execute the

PostgreSQL implements table inheritance, a feature that is an effective tool for database designers. The SQL99 and later standards define the type inheritance characteristics, which are different from the many features we describe here.Let's start

 Transferred from: http://time-track.cn/postgresql-window-function.htmlPostgreSQL provides the properties of the window function. The window function is also the data that computes some rowset (a collection of multiple rows, which we call window

Optimization of queries with any combination of multiple fields with high concurrency and low base. Optimization of highly concurrent and low-base multi-field queries with any combination 1. the problem first explains what the low-base multi-field

1. Connection Query Equijoin When the join operator is =, it is called an equivalent join. Other operators are called non-equivalent connections. Select student. *, SC .* From student, SC Where student. Sno = SC. SnO The SNO reoccurs in the

Transferred from: http://blog.jobbole.com/47892/Why do you have to put SQL on Hadoop? SQL is easy to use.Why does it have to be based on Hadoop? The robust and scalable architecture of HadoopCurrently, there are several main types of SQL on Hadoop