Database Administrator

1. Ensure that the source database is in the archive mode and the logging mode is mandatory.Shutdown immediate;Startup mount;Alter database archivelog;Alter database force logging;Alter database open;2. Make sure that you have created a password

Step 1 Verify that the primary database can be switched to the standby role.Verify that the master database can switch to the slave role.SELECT SWITCHOVER_STATUS from v $ DATABASE;Idle>: wq SWITCHOVER_STATUS--------------------TO STANDBY Step 2

SQL queries this week's questions this month --- Calculate the number of days for differenceSelect datediff (day, '2017-01-01 ', getdate ())-- 1. The first day of a monthSelect dateadd (mm, DATEDIFF (mm, 0, getdate (), 0)-- 2. Monday of the

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 system is RHEL5.3, 64-bit, XFS partition, 16 GB physical memory, BUFFER_POOL is set to 11 GB, DELL 2950 MYSQL5.5.20 binary version The system collapsed during initialization. Then, The system collapsed during dump. The system

B-tree Indexing is a complete technology for all large-scale relational databases and is also the default Indexing Technology for Oracle databases. Base Number: the number of different key values in the column you want to create an index. For

•What is an exception??Errors in Oracle are usually divided into compile-time errors and run-time errors ), an exception is a warning or error that occurs during PL/SQL Execution.•How is an exception triggered??-AOracleError-UseRAISEExplicit

I used MySQL on CentOS in the past. Later, because of the test requirements, I needed to migrate the website and data stored in the database to the new system for testing, the target system is RedHat Enterprise Linux Server (RHEL ). Since the

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

-- Functions and stored procedures can be defined separately. They will appear in pl/SQL-- Functions's folder and under the Procedures folder -- They can also be defined in the package. -- Functions or stored procedures defined in a package,

SQL> showparameter SQL NAME TYPE VALUE ----------------------------------------------------------------------------- Plsql_ccflags string Plsql_code_type string INTERPRETED Plsql_compiler_flags string INTERPRETED, NON_DEBUG Plsql_debug boolean FALSE

There is a new feature in Oracle 11g R2. When the table has no data, no segment is allocated to save space. Oracle cannot export empty tables when executing export, but there are still solutions: Solution: 1. insert a row and then roll back to

Recently, a database always reports the ORA-00600 ktrgcm_3 error, the version of which is Oracle 10.2.0.5.5 for linux x86_64.The error message is as follows:Fri May 25 14:10:41 CST 2012Errors in

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

Some basic concepts:A tablespace can belong to only one database at a time;In addition to the SYSTEM tablespace or the tablespace with active rollback segments, other tablespaces can be taken offline;Table space can be switched between read/write

Database associations are implemented through the primary and Foreign keys: The associations of object classes managed in Hibernate are implemented through inclusion. They are classified into one-way Association and two-way association based on

Since MySQL 5.5 released its first version, a new record is added to the GRANT permission list: PROXY. Do not think this is the previous MySQL Proxy. In fact, this is used as a vest for users. Let's take a look at the specific usage.Here, I use

The Flashback Drop flash-back deletion function of Oracle provides a convenient Recovery Method for deleting tables by mistake. The principle of this function is the RecycleBin function of Oracle. Note: If the table to be deleted is originally

Today, the following error occurs when you run your own JDBC to call the stored procedure:ORA-01002 read violation orderMost of the suggestions provided on the Internet are to set Automatic SQL submission to false: cn. setAutoCommit (false );But