Database Administrator

Goodbye to MongoDB, hello PostgreSQL Olery was founded almost five years ago. It started with the single product (Olery Reputation) developed by Ruby proxy. Over time, we began to work on a series of different products and applications. Today, our

Solutions to RMAN connection to secondary database ORA-04031 An error occurred while connecting to the secondary instance when Oracle 10 Gb built dg to use rman to copy the database. The error message is as follows:[Oracle @ oracle11g admin] $ rman

ORA-27090 error resolution instance The recent alert Log encountered an error message for the ORA-27090 with the error prompt Unable to reserve kernel resources for asynchronous disk I/O. According to this prompt, It is a kernel parameter problem

Oracle Database Remote Access through DBLINK What is DBLINK? A Database Link is a Database Link, just like a telephone line. It is a channel. When we want to access data in another Database table across local databases, you must create a dblink for

Initial Experience of MongoDB3.6 Replica Set Replica Set is called a Replica Set in China. Simply put, a copy of data is stored in multiple places. 1. Why should I use a replica set and when? Some people say that the storage of a piece of data

MySQL transaction and isolation levelPreface: I never thought of writing a good title. I want some important MySQL content. I have met either of the two interviews, but it seems that it is not appropriate to directly use the MySQL title. Simply

Oracle redo complexity-oracle Core Technology Reading Note 3, redo-oracle I. Overview We know that in oracle, Every modification to a piece of data generates a redo (that is, redo, which records the modified content ). The purpose is to back up the

How to handle archived log files and RMAN log files when using rman backupI went to a customer yesterday to deploy RMAN backup. when I ran the shell script, I was prompted that I could not find the archive log, because the customer only performed

The Efficiency Analysis and Improvement Methods of left join in SQL, leftjoin As the data volume and access volume of websites increase, the access speed slows down, so I began to find a solution to the slow speed of optimization. The following is

Comparison and Analysis of eight common NoSQL Database Systems Krist óf kolács is a software architect and consultant who recently published an article comparing various NoSQL databases. Although SQL database is a very useful tool, after 15 years of

MySQL foreign key details, MySQL key details Recently, when I was studying Hibernate, I was always confused by foreign keys. Moreover, my MySQL foreign key learning is not very solid, so in order to better master Hibernate and MySQL, therefore, I

MySQL Study -- Mysql startup failure "mysql. host", -- mysqlmysql. hostMySQL Study-Mysql startup failure "mysql. host" System Environment: Operating System: RedHat EL55 DB Soft: Mysql 5.6.4-m7 After mysql is installed through the source code

Basic SQL syntax and basic SQL statements A table that may be involved in an SQL statement: StudentInfo: PersonInfo: Test_outjoin: Test2_outjoin: Ii. Basic SQL syntax If exists (select * from dbo. sysobjects where name = 'studentinfo') -- Query

JDBC: database connection pool, jdbc database connection pool Required tools Commons-pool2-2.3.jar: dependency library implemented by connection pool Commons-dbcp2-2.0.1.jar: Implementation of Connection Pool C3p0-0.9.2.1.jar If Method

Typical use cases of MySQL MHA and typical use cases of mysqlmha1 Management node deployment location 1.1. Dedicated Manager server and multiple MySQL (master, slaves) servers Use a dedicated management server to manage multiple groups of MySQL

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Percona-toolkit installation and introduction, percona-toolkit MySQL database is one of the best lightweight and open-source databases. Its features, management, and robustness are quite different from those of Oracle. Therefore, there are many

Solve the Problem of CPU resource depletion caused by a large number of latch free databases in production. latchfree At noon, the cpu of a database we produced remained high. Using the following SQL statement, we can view the database waiting and

Run python on ubuntu to connect to pg. the following error occurs: ImportError: No module named psycopg2, ttupythonRun python on ubuntu to connect to pg. The error ImportError: No module named psycopg2 is returned.Root @ pgproxy1 :~ #

Fenng went to the Oracle Open World conference the day before yesterday and shared his experiences on Oracle Optimization on his blog. At Oracle Open World, Steve Shaw, the author of Hammerora, gave a speech about Oracle Optimization on the Linux