Database Administrator

Import and export of Oracle databases The import and export of Oracle databases is an important technical activity, which not only solves the import and export of databases, but also facilitates and quick data access. Use imp and exp to import and

How Does Oracle Randomly Read values from a specific combination? Here, we will use the DBMS_RANDOM package and the case when statement as follows: 1. Use the DBMS_RANDOM.RANDOM function to randomly generate a value and then modulo the value. If we

Distributed Session based on Redis 1. OverviewWe can implement a Session-like mechanism by ourselves, using Redis and other distributed cache middleware. Redis is independent of the Application Server. The Session mechanism based on Redis

Oracle cannot change the tablespace to the backup mode in non-archive mode. After the Oracle tablespace is set to the backup mode, you can copy and back up the data files in the table space online at the file system level, because modifications to

Distributed Message Queue Based on Redis 1. Why do I need a message queue?When factors such as the speed or stability of "production" and "consumption" are inconsistent in the system, a message queue is required as an abstraction layer to bridge the

A brief comparison of SQL parsing details in MySQL and Oracle The SQL syntax parser is a powerful built-in tool set that involves a lot of compilation principles, including syntax analysis and lexical analysis .. There are a lot of things that seem

Sysbench benchmark, sysbench Benchmark 1. Introduction Sysbench is an open-source multi-threaded performance testing tool that can perform performance tests on CPU, memory, thread, IO, and database. The database currently supports MySQL, Oracle, and

[Niuyun Video] SQL trigger and niuyun SQL trigger I learned about the data center management system. I have already written about database operations in the net version, but now I am learning about it, only to find that I have understood it

Mysql paging negative SQL attack, mysql paging SQL1. Attack Analysis CleverCode's O & M colleague told me that when he checked the mysql error log, he found a large number of errors, so someone was attacking a specific address. This error occurs

Redis installation error: jemalloc/jemalloc. h: No such file or directory solution, redisjemallocError description When installing Redis 2.8.18, an error is reported: zmalloc.h:50:31: error: jemalloc/jemalloc.h: No such file or directoryzmalloc.h:5

Mybatis single parameter if judgment (for exception: There is no getter for property...), mybatisgetter We all know that mybatis can directly use to determine the parameters, as shown below: 1. General Code update t_test_l

Mysql database backup mysqldump, database backup mysqldump The mysql database server needs to be backed up recently. The following problems are solved in sequence. 1. [SQL] mysqldump-uroot-proot tms> tms_201505133 SQL [Err] 1064-You have an error in

Semi-sync settings for m-s and semi-sync settings for m-sMaster: Install the semi-sync plug-in(System @ localhost) [(none)]> install plugin rpl_semi_sync_master soname 'semisync _ master. so ';Query OK, 0 rows affected (0.83 sec)(System @ localhost)

Mysql innodb engine's shared and independent tablespaces, mysqlinnodb For innodb data storage files, we must first solve two conceptual problems: Shared tablespace and exclusive tablespace. (The innodb engine and MYISAM engine are very different. In

Mysql group by with rollup, mysqlrollup 1. Common group by operations can be grouped BY department and position to calculate the average salary of each department and position: mysql> select dep, pos, avg (sal) from employee group by dep, pos; + ----

MySQL DATE_FORMAT () function, mysqldate_formatDefinition and usage The DATE_FORMAT () function is used to display date/time data in different formats.Syntax DATE_FORMAT(date,format) DateThe parameter is a valid date.FormatSpecifies the output

Understanding of MySQL database DELAY_KEY_WRITE, delaykeywrite MySQL database parameter DELAY_KEY_WRITE: DELAY_KEY_WRITE refers to the update operation of the table to the disk without updating the index to the disk before the table is closed, and

ORA-04030, ora0403032-bit-- Error: 20 m unavailableDump continued from file:/u01/app/oracle/diag/rdbms/szaa/szaa2/trace/szaa2_dw01_122659.trcORA-04030: out of process memory when trying to allocate 24520 bytes (koh-kghu sessi, kpmalloc)-- 4 GB

Oracle 12c connection errors reported ORA-28040 problem solution, 12cora-28040Problem description: When the client connects to Oracle 12c, an error is reported: ORA-28040: No matching authentication protocol Cause: The SQLNET.

MySQL uses the index scenario and the SQL type that actually uses the index, mysqlsql 1. Why are indexes used?Without an index, MySQL scans the entire table to find records that meet the SQL conditions. The time overhead is positively related to the