Management process and session

/ * Management server mode * /

By default, in addition to the OLTP type database, DBCA created databases are used to determine the database current mode of operation using a private server operating mode: SQL> SELECT Server 2 from v $ session 3 where audsid = sernv ('sessionID');

Server ----------------- Dedicated

/ * Monitor process status * /

Each service process and the background process have a corresponding tracking file. The name of the warning file is usually alert.log. It is a special tracking file that records the DBA level management operation in the database and an error inside the instance Information, including: * All occurred internal errors (ORA-600), block corruption errors (ORA-1578), deadlock errors (ORA-60) * All executed DBA operations (Create, Alter, Drop, Startup, SHUTDOWN and other statements) * Information related to shared service processes and scheduling processes and error messages * Database and instance startup

The storage location of the tracking file and warning file is specified by the following two initialization parameters: background_dump_dest: The tracking file of the background process and the position of the warning file, the default is Oracle_base / admin / bdumpuser_dump_dest: The location of the service process is located, default is Oracle_Base / Admin / Admin / udump

/ * Manage user sessions * /

When a session is aborted, the uncommitted transaction in the session is retired. SID: Session System Identifies the Serial #: Session Sequence Identifier You can uniquely determine a session in the instance through the session system ID and session sequence identifier. Oracle can also distinguish Two connections to the same user.

View session: SQL> Select Sid, Serial #, Username, Osuser, Status 2 from V $ Session 3 Where Osuser = 'Keke';

SID Serial # Username Osuser Status ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ------------------ 113 12291 BSP Keke Inactive 199 26450 BSP Keke Inactive

Survival session: SQL> ALTER SYSTEM KILL Session '113, 12291';

/ * Management transaction * /

The transaction is a logical unit in a work that contains one or more SQL statements, which is an indivisible minimum unit.

When there is a case, Oracle thinks an end: * User executes a CommT or rollback statement * User executes a DDL statement * User actively disconnects to Oracle connection, then the current transaction is automatically submitted to the user process accident stop At this time, the current transaction will automatically fall back.

Oracle is completed at the time of transaction: * This transaction has been submitted in the internal transaction table in the retracted section specified for the transaction, and generates a unique system change code (SCN) record in internal transactions, The only identity this transaction * LGWR will redo the redo record in the log cache written to the online redo log file, and write the redo log while writing the SCN * Oracle service process release of the transaction. Record lock and table lock * Oracle Notification User Transaction Submit Success * Oracle marks the transaction as completion

Steps to retreat to the entire transaction: * Oracle By using the rollback entry in the retreat section, revocation all SQL statements in the transaction * Oracle service process release transaction all locks * Oracle Notification User Transaction Success * Oracle marks the transaction as completion