Database Administrator

PostgreSQL recursive query for Tree Structure Query A very interesting feature found during PostgreSQL's use is that recursive queries can be used for results that require a tree-like structure. For example, the data structure of common company

Duplicate data read at the REPEATABLE-READ isolation level of MySQL" In MySQL, MVCC is used to implement the REPEATABLE-READ isolation level, because the SELECT operation does not lock the data, other calls can modify the data read by the current

Monitor MySQL Master/Slave synchronization latency There are usually two ways to monitor the latency between MySQL master and slave: Seconds_Behind_Master and mk-heartbeat. Method 1: monitor the value of the Seconds_Behind_Master parameter output by

MySQL slow query log MySQL supports slow query logs. You can configure query records that have exceeded the specified time for SQL query to log. This is a very effective tool in optimizing SQL queries and can help us quickly locate the problematic

The MySQL database of Ubuntu 15.04 allows remote connection to Toad. I installed Ubuntu 15.04 IN THE vmwarevm. mysql service can be enabled. However, when Toad is used for remote connection, the connection fails and an error message is displayed.

Configure HugePage for Oracle 11gR2 in Linux HugePage is a performance optimization tool for Oracle in Linux. For database systems in the shared memory area (SGA), we recommend that you configure HugePage at the operating system level to provide

Ubuntu 10.10 Oracle 10g Installation Guide Ubuntu 10.10 Oracle 10g Installation Guide Step 1: Download The oracle10 installation package (server and

MySQL Tutorial: About the checkpoint Mechanism I. Introduction Think about this scenario: If the redo log can be infinitely increased and the buffer pool is large enough, you do not need to refresh the new version of the page in the buffer pool to

Hive processes count distinct to produce data skewProblem description The problematic data is skewed to the category, but it cannot be joined on the Map side, and special keys are excluded for processing. set hive.groupby.skewindata=true;insert

MongoDB basic operation learning notes Record the basic operations of MongoDB today. This is only the most basic operation, so it should be mastered. Database A database is a collection of physical containers. Each database has its own file system.

The simplest MySQL tutorial in history (40) "database variables 」, Tip: This series of blog posts have been synchronized to GitHub. The address is "mysql-tutorial". Thank you for your interest.Star,Fork, Error correction. Variable In the MySQL

Redis data type and Application Scenario, redis data type scenario I. redis features All data is stored in memory and read/write at high speed Provides a wide range of data types: string, hash, set, sorted set, bitmap, hyperloglog The AOF and

Build a MYSQL master-slave replication structure and a mysql master-slave replication Structure 1. Select two servers as the master and backup databases respectively. 2. log on to the server, Yum install mysql; Yum install mysql-server; 3. Start the

Lesson 5 MongoDB Data Query (II): mongodb Data Query1. Course outlineThis course continues to explain MongoDB Data Query related content, including MongoDB cursor, fuzzy query, and use of findAndModify functions. 1. MongoDB cursor 2. fuzzy query 3.

Create users and permission settings in Oracle, create permissions in oracleOracle user creation and permission settings Permission: Create session Create table Unlimited tablespace Connect Resource Dba Example: # Sqlplus/nolog SQL> conn/as

Common Database interview questions and database questions Paradigm 1: Each column in a database table is a basic data item that cannot be further divided. values or duplicate attributes are not allowed. For example, if a table contains a phone

Oracle row-to-column summary and oracle column-to-column Summary Recently, I have applied row-to-column conversion in my work. Here I will make a simple summary. The conversion process is as follows: 1. Create a table structure CREATE TABLE

PL/SQL connection to the Oracle database -- no connection is required, ploracleZookeeper The 64-bit Oracle database installed on Win 7 is then installed with a 32-bit Oracle client. When you connect to Oracle using PLSQL, only the username, password,

Before talking about the locking mechanism of SQLServer, let's think about the following scenario: When you ride your car to your destination during the hot summer, there are several long red lights on the road, is it depressing? Sometimes you may

We know that the website background needs to verify the user input. If this is not done, the user can even enter some SQL statements to operate the background database. Such a fun thing has never been really experienced. A few days ago, the School