Database Administrator

HBase adopts the master/slave Mode in distributed deployment. It consists of three major functional components: RegionServer, MasterServer, and ClientLibrary. Hadoop HDFS sub-framework is used in distributed storage. Distributed computing functions

No one wants to lose the key to the house, but no matter how careful or long, such a thing will always happen several times. The same is true for MySQL passwords. It is not safe to write them in documents, and it will inevitably be forgotten in your

The default redo log file size of Oracle10g is 50 MB. in use, it is often found that there are a large number of Checkpoint not complete problems in alter log. We should all know what this problem is. To solve this problem, we only need to increase

In Oracle, the Number type can be used to store 0, positive, negative, or floating point numbers. The data range can be 1.0*10 (-130) -- 9. 9... 9*10 (125) {38 9 followed by 88 0} digits. When the value of the mathematical expression in Oracle is

I recently looked at a blog and found that Oracle 11g provided the new feature of user rename. In a 10g environment, if you want to rename a user, you should first create a new user and authorize it, import all objects under the original user and

I am writing a software program on the Linux platform and need to use a simple database. Mysql is a good database, but its data is stored on the server. The basic function I want is to create a local database file using program C, and then perform

ViewA view is a unique object in a database. Views are used to store queries, but data is not stored (except materialized views ). This is an important difference between a view and a data table. You can use views to query, insert, update, and

The Iterate label of Ibatis can be used to traverse every element of the List cyclically to form an SQL file dynamically. But how can I use Iterate to traverse a nested List, after a lot of experiments, I finally found this method. The Code is as

MySQL Replication is usually used for MySQL services for read/write splitting, HA, hot backup, or incremental operations, and the Master/Slave mechanism is indispensable. However, errors 1032 and 1052 are reported in many cases. First 1032. Error_

We can directly modify it through the SQLPLUS client, or in linux, but the commands are the same. Next we will focus on the introduction in linux: Su-Oracle Sqlplus/nolog Connect/as sysdba Alter system set processes = value scope =

This article is a by-product study of Mongodb distributed data storage. Through the relevant steps in this article, we can distribute data in a large table to several mongo servers. In MongoDB 1.6, the auto-sharding function is basically stable and

When the control file is corrupted for databases earlier than Oracle 11g, when we mount the database, there will be a significant ora-600 error, so it is easy to know the control file corruption error, however, oracle 11g R2, At that time, it was an

Parallel (Parallel) and OLAP SystemsParallel Implementation Mechanism: first, Oracle will create a process to coordinate information transmission between parallel service processes. This coordination process will operate on the dataset (such as the

I. Test preparation 1. Create a table data space SQL> create tablespace cat_data nologging Datafile '/home/Oracle/app/oracle/oradata/catdb/cat_data.dbf' size 4096 M Extent management local autoallocate; 2. Create a table index space SQL> create

Oracle has been in use for a long time, and many new users and tablespace are added. You need to clear them. For a single user and tablespace, you can use the following command. Step 1: delete a user Drop user ××cascade Note: If a user is deleted,

In Oracle 11g, add a disk to an existing disk group. The operation command is "alter diskgroup webdg add disk '/dev/raw/raw4 ';", however, if you use sysdba for connection, an error is returned. ORA-15260: permission denied on ASM disk groupInform

RedHat version: 6.2 Mysql version: mysql-5.5.19 Installation Package file name: mysql-5.5.19-linux2.6-x86_64.tar.gz 1. installation steps: Download the mysql-5.5.19-linux2.6-i686.tar.gz package from the official network. Decompress this package and

Synonym: literally, it means an alias, which is similar to an attempt. Is a ing relationship. (1. Create a synonym statement: Create public synonym table_name for user. table_name; The first table_name and the second table_name can be different.

I. Basic Concepts MongoDB is a high-performance, open-source, and non-pattern document-based database. It is currently the most popular NoSQL database product. It can be used in many scenarios to replace traditional relational databases or key/value

Cause: The SQL statement is as follows: Select count (*) from test; Result 1390. Select count (*) from test where bb not like '% disable %' Result 393. In the actual browsing process, it is found that the result set is not disabled and there