Database Administrator

HBase cannot assign permissions to users HBase cannot assign permissions to users and reports an error. Problem background description: In the test environment, hdfs is formatted. Many hdfs-based environments are affected. Hbase is also affected.

Ambari Hive cannot be properly queried 1. An error occurred today. After connecting to hive, no command can be executed. $ Beeline-u "jdbc: hive2: // hostname.domain.cn: 10000/default; principal = hive/_ HOST@domain.com ;"Connecting to jdbc: hive2: /

ORA-39126 ORA-00904 ORA-06512 Solution Process Expdp test/123456 dumpfile = B. dmp directory = DUMP_DLSPThe following error occurs when using data mercury. According to the parameters I used, no advanced parameters are used, which are the most

Quick install of MongoDB in Linux MongoDB is a non-relational database (NoSql) that is very popular in the IT industry. Its flexible data storage method is favored by current IT practitioners. MongoDB implements the object-oriented idea (OO idea),

After the Oracle 10g Database is installed, the web page is installed by default to manage the Oracle access path, including: Em: http: // localhost: 1158/em Isql * plus: http: // localhost: 5560/isqlplus and http: // localhost:

Explain the Oracle imp exp command, impexp How to import dmp database files in oracle? Importing and exporting oracle Data imp/exp is equivalent to restoring and backing up oracle data. The exp command can export data from the remote database server

Oracle date weekly explanation and weekly start and end time calculation, oracle End Time 1 ORACLE weekly knowledge description 1.1 date formatting Functions TO_CHAR (X [, FORMAT]): Convert X to a string in FORMAT. X is a date, and FORMAT is a

Basic Database knowledge and database knowledgeTransaction ACID atomicity (atomicity) Each transaction is an inseparable minimum unit. Operations in the transaction are either all successful or all fail to be rolled back.Consistency) The result of

[Mysql] After windows is reinstalled, mysql and "Access denied for user 'root' @ 'IP'" are restored. mysqldenied Mysql databases are actually green software and can still be used after the system is reinstalled. 1. Reload the system and keep the

Mysql installation-free version configuration and mysql installation-free version Configuration Decompress mysql-5.7.17-winx64.zip to D: \ database Modify configurations Create my. iniThe configuration is as follows: [Client] # set the default

MySQL loads the JDBC driver and mysql loads the jdbc driver. First, install the MySQL database. MySQL5.5 is installed. The installation steps are not described here. Please note that if the installation process stops at the start service and

Overview I wrote about the Server login name, server role, database user, database role relationship, and theoretical knowledge in a previous blog. You can refer to this blog: Login Name, server role, user Name and database role. This blog focuses

Oracle databases differ significantly from MSSQL data operations, but there is an analogy in image operations. This article describes how MSSQL database images are implemented in Oracle databases. What are the differences between them.First, the

Innodb_adaptive_flushing= {ON | OFF}Set whether to allow the MySQL server to dynamically adjust the dirty pages in the InnoDB buffer pool based on the workload. The purpose of dynamically adjusting the write speed is to avoid IO activity spikes. The

With the concept of big data gradually increasing, how to build an architecture system that can collect massive DATA is in front of everyone's eyes. How to achieve what you see is what you get, how to quickly structure and store irregular pages, how

Prior to data import, the DB2 database system often checks the format of external files carefully. If the format of the external file does not meet the mandatory requirements of the database, the database will refuse to import data. This time I will

Use SQL statements to connect two tables in different databases on two different servers. Initially, the SQL statements are written as follows: Select*FromProduct pInner Join  Opendatasource ('Sqlodb','Data Source = Macaco-Online; user ID =

1. Fuzzy match of the query Try to avoid using LIKE '% parm1 %' in a complex query -- the percentage sign of the red flag will make the index of the relevant column unusable. Solution: In fact, you only need to slightly improve the script, and the

If multiple groups of duplicate PK Values exist in the table, it takes a lot of time to delete them one by one. In this case, you can use the following method: 1. First, run the group by query above to determine the number of repeated PK values and

In databases, the Redo function is mainly implemented through three components: Redo Log Buffer, LGWR background process, and Redo Log File in archive mode, the Redo Log File will eventually be written as an archive Log File ). There is a shared