Database Administrator

Use expdp (non-local) to remotely export data Background: Some time ago, test data (one table) needs to be imported into the local database from a remote test database. The table has about 5 million data records and more than 160 fields. The exp/imp

MySQL database index Advantages of creating an index in MySQL: 1. Greatly speed up data retrieval; 2. Create a unique index to ensure the uniqueness of each row of data in the database table; 3. Accelerate the connection between tables; 4. When you

Database and database LearningPhysical Optimization Algebraic optimization changes the order and combination of operations in a query statement, and does not involve the underlying access path.There are many access solutions for a query statement,

How to generate a random number in Oracle. Dbms_random is a package that can generate random values or strings. Dbms_random.value Method 1. Decimal (0 ~ 1) Select dbms_random.value from dual; 2. decimal places in the specified range (0 ~ 1

Redis data structure (1) Simple Dynamic string and redis Data Structure Redis uses a custom struct string called simple dynamic string (SDS ).The structure is as follows: struct sdshdr{int len;int free;char buf[];}; The advantages of using such a

Database and database LearningData Dependency System Logic Implication definition 6.11 For the relational mode R that satisfies a set of function dependencies F, any of its relational r is true if function dependencies X → Y, (that is, any

Database and database LearningBC Paradigm (BCNF) Relational mode R ε 1NF. If X → Y and y x are required to contain the code, R ε BCNF. This definition indicates that, if the non-trivial fd x → Y contains no code, Y must be passed depending on the

[Opening for Oracle Database beginners]: oracle Database beginnersDue to project reasons, I recently started to study Oracle databases. Oracle is currently one of the most popular databases, with powerful functions and excellent performance. It is

Error code: 1054 Unknown column 'Course' in 'field list', 1054 column 1. Error description 1 queries executed, 0 success, 1 errors, 0 warnings query: SELECT stu_name, course, score FROM t_student_info s LIMIT 0, 1000 error code: 1054 Unknown

Oracle modifies port 8080Zookeeper 1. log on to the database with the sys account Run the following command under SQL plus: conn sys as dba; press enter and enter the password. Tip: If the connection is successful, proceed to step 2. 2. Modify

For the content of eight Oracle 12.1.0.2 files, oracle12.1.0.2 Source: P17694377_121020_Linux-x86-64_1of8 \ database \ readme.html     Oracle Database (des Oracle Database, Oracle RAC, and Deinstall)Note: you must download both zip files to

Consistency Test and open consistency test in the open stageIn the open stage, oracle requires consistency check before it can open the database. What tests have been done?Check whether the Checkpoint CNT in the data file header is consistent with

Database paradigm-General handouts and database paradigm HandoutsWang Shan's introduction to database systems, a textbook used by most colleges in China, does not provide a very detailed and clear explanation in some aspects, and is not closely

Use innobackupex to build a mysql master-slave architecture based on the slave database, innobackupexmysql There are many ways to build MySQL Master/Slave databases. The traditional mysqldump mode is one of the choices of many people. However, this

HRegionServer Flush source code analysis, hregionserverflush The Flush operation is the process of saving HBase data to the hard disk. The specific flush flowchart is as follows. This article briefly analyzes the source code of the flush

Aerospike C client manual --- aggregation-record aggregation, aerospike ClientRecord Aggregation There are various forms to process the secondary index query results. A common form of aggregation is to apply a function to the entire query result set.

7 Managing Database Workload Using Services, managingworkload7. Managing Database Workload Using ServicesNote:A database service can only be offered on a single network.Caution:By default, any named user may create a server pool. to restrict the

Oracle uses order by to sort null values. oracleorder When order by is used in Oracle for query and sorting, if there is a null value in the sorting field, the sorting result may not reach the expected result. For example: Select * from test

PostgreSQL tutorial (9): Introduction to transaction isolation, postgresql tutorial In the standard of SQL, the transaction isolation level is divided into the following four types:1. Read uncommitted)2. Read committed)3. Repeatable read)4.

SQLite tutorial (7): Data Type Details, sqlite Data Type I. Storage types and data types: SQLite divides data values into the following Storage types: Copy codeThe Code is as follows:NULL: The value is NULL.INTEGER: unsigned INTEGER value.REAL: