Database Administrator

In the update optimization, considering the efficiency of the update from is relatively high, but because Oracle will check the key value, resulting in a ora-01779 error, by using BYPASS_UJVC to skip the Oracle key determination, achieve the same

The Oracle storage outline is used to provide stable execution plans. Starting from oracle 11g, it is gradually replaced by the SQL plan. The following describes the specific process of the storage outline. The results are tested in oracle 11g r2.--

Dex is an open-source MongoDB optimization tool. It analyzes query logs and current database indexes and proposes efficient index optimization policies to administrators.Quick Start Installation pip install dexStart monitoring dex -f mongodb.log

One node of a core library went down last night, and then reboot, The following information is found in alert: Thu Jul 5 03:03:50 2012 Errors in file/u01/Oracle/app/oracle/admin/crm/bdump/crm1_dbw9_142.16.trc: ORA-07445: exception encountered:

1. Solve directory Problems [Ora @ rac1-21 bin] $ srvctl/U01/Oracle/product/10.2.0/db_1/jdk/jre/bin/java: error while loading shared libraries: libpthread. so.0: cannot open shared object file: No such file or directory [Ora @ rac1-21 bin] $ which

Whether we use dbca for database creation or manual creation. After the database creation task is completed, three parameters are very important for future production and use. Generally, we need to open them.The first one is log_checkpoints_to_alert.

The "Recycle Bin" (Recycle BIN) concept is introduced in Oracle Versions later than 10 Gb. The deleted objects are all placed in the Recycle Bin and named with the BIN $ prefix. A user can easily restore a table from the "recycle bin", but before 9i,

DRCP is the Database Resident Connection Pool. The default Database is sys_default_connection_pool, but it is not opened. Start DRCP:Sqlplus/as sysdbaExecute dbms_connection_pool.start_pool ();It can be executed on any instance in the RAC

There is a problem that has been confusing for a long time. When Oracle 10g rac is upgrading crs, it should fail. RAC is a joke. This test is completed on the Linux platform. Exercise caution when operating the production database. 1. Back up ocr

The table names imported to the database are garbled due to inconsistent codes and cannot be deleted. The names of tables whose names start with numbers and whose names contain invalid characters cannot be deleted. It is said that the card cannot

The following documents are easy to translate from the official Oracle dba documents. Manage redo log files Objective:1. Explain the purpose of redoing log files2. describe the structure of the redo log file3. Learn to control log switching and

SAVEPOINT http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_10001.htm#SQLRF01701 provided by official documentation 1. Purpose: Use the SAVEPOINT statement to identify a point in a transaction to which you can later roll back. Use the

First, check the machine environment and check whether there are any residual database installation directories and related users. If they are found, they will be deleted.Check whether the/opt/IBM directory contains db2 files.Next, let's look at the

When writing a report today, you need a table in another database to operate (table_name). However, during the operation, this table has a large field (clob. No query is available using select * from table_name @ dblink. Always reports errors. Then

1. rollback and Revocation Refer: In-depth Oracle parsing by eygle (1) In order to ensure read consistency among multiple users and to roll back transactions, oracle provides the old values before the modification for the modified data. (2)

Add a log group in Oracle and some commands for log members1. Add a log group: Alter database add logfile group 4'/oradata/oracle/oradata/oracle_sid/redo04.log 'size 100 M; 2. Change the log group size ( First, check the archiving status: SQL>

Architecture and Backup recovery principles1. The most important thing about Oracle database is online redo log.AnalogyControlfile: corporate executivesDatafile: Production WorkshopOnline redo log: Finance DepartmentNote:System tablespace is the

Requirement: Now you need to change the field name, add a field, delete another field, and change the field type. Create the following table (original table ):Create table month (Id INT,Week VARCHAR (10 ),Day VARCHAR (10 ),Hour VARCHAR (10 ),Primary

Oracle logminer is a tool used to analyze archived logs. Here I will list a simple and efficient use process. 1. initialize parameter configuration Alter system set utl_file_dir = '*' scope = both; This requires a restart to take effect. SQL> show

Mysql backup and AB ReplicationThere are two replication methods: Synchronous replication (msylq-cluster) asynchronous replication (mysql-m/s master-slave backup is also called dual-machine Hot Backup) I. Mysql full backup (pure copy mode and