Database Administrator

V $ database: database information, such as the database name and creation time. V $ instance information, such as instance name and start time. V $ parameter information, select * from v $ parameter where name like '% name' ----> show parameter

Generally, Oracle cannot be started. It only appears when an exception occurs. At this time, there are usually prompts, the most common is that a parameter cannot be found, or the connection pool/Shared Pool settings are too small. You can do this

A properly configured Mongodb sharding cluster does not have a single point of failure.This article describes several potential node failure scenarios in a sharded cluster and how Mongodb handles these node faults. 1. Mongos node downA Mongos

Building an Oracle two-way stream replication is a very complicated process. The purpose of writing this document is to list what needs to be done in an organized manner as much as possible to help DBAs build a stream replication environment more

When the data block in the buffer cache is modified, the server process generates redo data and writes it to the redo log buffer. When the following conditions are met, LGWR will write the entries in the redo log buffer into the online redo log:--

Super User problems: Use admin # Adding or modifying user passwords Db. addUser ('admin', 'pwd ') # Viewing the user list Db. system. users. find () # User Authentication Db. auth ('admin', 'pwd ') # Deleting a user Db. removeUser

1. To enable Python to operate the MySQL database, first install the MySQL-python package. You can run the following command on CentOS to install the package: [Python] $ Sudo yum install MySQL-python 2. Leave nothing to say. Take two steps. The

71. your database instance is started using the server parameter file (SPFILE ). control files are multiplexed and stored on different disks. because of a disk failure, you lost one of these control files. you replaced the damaged disk. what is the

The old system has been operating normally and suddenly the database cannot be accessed, as shown below: Aix5.3 system with Oracle9i installed Log on to the aix system and find that the listener has been interrupted. Prepare to restart the database.

Introduction: Two installation methods: Binary File Installation andCompile and install(This article uses the binary installation method. If you are interested, try to compile and install your own shoes) Environment Ubuntu-11-10 32BitPreparation 0.

When we perform monitoring checks on the memory usage of db2, we often need to know the current memory usage of db2. The instance_memory parameter cannot be used to accurately view the information, because instance_memory includes mon_heap, memory

The ANSI/ISO SQL92 standard defines the isolation levels for some database operations: 1. uncommitted read (read uncommitted) 2. read committed) 3. repeatable read) 4. serializable) Lock Mechanism: Shared lock: other transactions can be read but

1. view the size of all tablespaces SQL> select tablespace_name, sum (bytes)/1024/1024 M from dba_data_files group by tablespace_name; 2. Used tablespace sizeSQL> select tablespace_name, sum (bytes)/1024/1024 M from dba_free_space group by

1) Background: Recently, an Oracle10g RAC dual-node experimental platform was built in vmware and oracle RAC was upgraded from 10.2.0.1 to 10.2.0.5. Later, it was found that the two linux systems often restarted automatically; 2) platform

When we write SQL statements, we often ignore some details. The following is a summary of my own operations and materials. If there is something wrong or something wrong, hope to reply to me and learn from each other. Thank you!1. When a full table

When a table is accidentally deleted, hundreds of mb of data is lost? No. Now you don't have to worry about it. Oracle9i and above use a garbage collection solution, and it's easy to recover. No longer use precious time for database cloning/exp/imp

In addition to the preceding view, Oracle also has a set of virtual tables used to record the current database activity. As the name suggests, dynamic performance tables are not real tables. Therefore, not all users can access these tables. However,

I. Disk Space Restoration:In PostgreSQL, the data rows deleted or updated using the delete and update statements are not actually deleted, the physical address of the old data row sets the row status to deleted or expired. Therefore, when data in a

Previously written: This operation adds uppercase letters. DELIMITER $ USE't _ girl $ DROP FUNCTIONIf exists 'func _ rand_string '$ CREATEDEFINER = 'root' @ 'localhost'FUNCTION'Func_rand_string '(f_num tinyint unsigned, f_type

Oracle asmlib is a system package provided by Oracle on the linux platform to replace raw devices. It is easy to install and configure. You can refer to my article. This article describes a small problem that occurs during the use of replicel asmlib.