ORA-02049: Timeout: Distributed Transaction Processing wait lock Simulation

ORA-02049: Timeout: Distributed Transaction Processing wait lock Simulation I want to simulate this error and see what the problem is. Create a table on Oracle Database B: Create table TEST(A number,B DATE);Insert into test (A, B) values (2, to_date

Usage of order

Usage of order 1. Processing of null in order Default processing: Oracle considers null as the maximum value in order by, so if it is asc, it is placed at the end, and desc is placed at the top. We can use nulls first or nulls last to control the

Differences between rank () over, dense_rank (), and row_number () in Oracle

Differences between rank () over, dense_rank (), and row_number () in Oracle Differences between rank () over, dense_rank (), and row_number () in Oracle Suppose there is a student table student, which contains the name, score, and course number.

Oracle Database time and system time

Oracle Database time and system time There is a huge gap between Oracle Database time and server system time, resulting in data confusion and report errors. The difference between database time and system time is about 16 hours. The details are

MongoDB Tutorial: MongoDB cluster and replica set

MongoDB Tutorial: MongoDB cluster and replica set Concepts For MongoDB Data Disaster Tolerance, the recommended mode is the replica set mode. It has an external Primary server Primary and N replica servers Secondary (N> = 1, when N = 1, an

MHA installation and equivalence Configuration

MHA installation and equivalence Configuration MHA consists of MHA nodes (which can be understood as subnodes) and MHA management nodes. Therefore, MHA installation is divided into two parts: Install MHA nodes and install MHA management nodes. This

Introduction to Oracle RAC clusters, processes, and logs

Introduction to Oracle RAC clusters, processes, and logs In a single-host environment, Oracle runs on the OS Kernel. OS Kernel manages hardware devices and provides hardware access interfaces. Oracle does not directly operate the hardware, but has

Comparison and learning between MySQL and Oracle

Comparison and learning between MySQL and Oracle The storage engine in MySQL is very rich, commonly used include InnoDB, MyISAM, and so on. I also read a lot of information and have some knowledge about it, from some reference books, I can see that

Brief description and example of MySQL Replication

Brief description and example of MySQL Replication Master-slave replication is widely used in MySQL. It is mainly used to synchronize data on one server to multiple slave servers. It can be used for load balancing, high availability and failover,

Oracle 11gR2 changes the user, causing the system to HANG

Oracle 11gR2 changes the user, causing the system to HANG [Background] at noon today, the user reported that the connection password between the database and the application needs to be modified, and the password should not be changed. I did not

An error occurred while using DBCP in AbstractMethodError.

An error occurred while using DBCP in AbstractMethodError. An exception occurred while using DBCP. Error description: Exception in thread "main" java. lang. AbstractMethodError: com. mysql. jdbc. Connection. isValid (I) ZAt org. apache. commons.

Quickly build a slave Database Based on mysqldump

Quickly build a slave Database Based on mysqldump Mysql master-slave architecture is generally divided into three steps: one is to add the parameters required for replication to the master instance and the other is to create a snapshot in the master

How to Create a LocalDB database and database instance

How to Create a LocalDB database and database instance LocalDB is a new feature of SQL Server 2012. It is a lightweight database tailored for developers. The following describes how to use it. How to Create a LocalDB database: Open the Server

Optimization of MySQL in high memory and IO Utilization

Optimization of MySQL in high memory and IO Utilization The following optimizations are based on some MySQL Optimizations in the CentOS system. We hope to continue to improve them if they are incomplete or controversial.I. mysql-level optimization 1.

MySQL Backup recovery based on LVM Snapshot

MySQL Backup recovery based on LVM Snapshot Directory1. Full database backup2. Prepare LVM volumes3. Data Recovery to LVM volumes4. Back up data based on LVM snapshots5. Data Disaster Recovery6. Summary Preface:The mysql 5.5.36 database is installed

Install and configure MongoDB 2.4.10

Install and configure MongoDB 2.4.10 IntroductionMongoDB is a distributed file storage-based database. Written in C ++. It is designed to provide scalable, high-performance data storage solutions for WEB applications. FeaturesHigh performance, easy

Semi-synchronous replication instance of MySQL5.6 one master and multiple slaves

Semi-synchronous replication instance of MySQL5.6 one master and multiple slaves Semi-sync introduction:By default, MySQL replication is asynchronous, which means that the master server and its slave server are independent. Asynchronous replication

Simple cold backup synchronization for Oracle databases in Linux and other Windows systems

Simple cold backup synchronization for Oracle databases in Linux and other Windows systems We have a financial system that focuses on the security of financial data. At the same time, we have two systems: a production environment (Linux) and an

Multi-channel archiving of Oracle databases to prevent single point of failure

Multi-channel archiving of Oracle databases to prevent single point of failure I. It is usually used to solve the following problems:Database hang problems caused by full archiving DirectoriesArchive multiple paths to prevent spof 2. the

Ajax calling in Oracle Application Express (APEX 4.2)

Ajax calling in Oracle Application Express (APEX 4.2) Oracle Application Express 4.2 (APEX 4.2) is a quick Web Application development tool. Ajax requests are sometimes used during web page development. How to create an ajax request: 1. Create

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