Basic Concepts Tablespace Overview An Oracle tablespace is a logical storage structure used to store database objects such as data files. Its the largest logical unit of information storage in Oracle, containing segments, extents, and data blocks. A tablespace provides a logical container for databa...
Methods for Retrieving Execution Plans Database administrators and developers rely on several techniques to capture how the Cost-Based Optimizer (CBO) resolves SQL statements. Each method offers distinct advantages regarding runtime statistics, historical analysis, and overhead. 1. EXPLAIN PLAN FOR...
Oracle Password Expiration Configuraton Oracle's DEFAULT profile sets PASSWORD_LIFE_TIME to 180 days by default, causing passwords to expire and potentially disrupt application connectivity. Checking Current Password Expiration To check a user's password expiration date: SELECT username, profile, ex...
Environment Architecture The deployment involves a primary cluster operating in an active-passive configuration and a two-node physical standby cluster. The primary database instances reside on prod-node1 (active) and prod-node2 (passive). The standby instances are hosted on std-node1 and std-node2....
Understanding Log File Sync Wait Events When a user commits or rolls back a transaction, the session's redo information must be written to the redo log files. The user process signals the LGWR (Log Writer) to perform the write operation, and the LGWR notifeis the user process upon completion. The &q...
Cluster Startup Sequence The operating system initiates the ohasd process, which subsequently launches agents responsible for starting core daemons such as gipcd, mdnsd, gpnpd, ctssd, ocssd, crsd, and evmd. The crsd daemon then utilizes agents to bring up user-defined resources like databases, SCAN...
Oracle Flashback Technology provides rapid data recovery solutions, reducing recovery time from hours to minutes. It enables selective undoing of errors at various levels including row, transaction, table, and entire database operations. Core Concepts Undo Segments Undo segments store pre-change dat...
-- table used in the examples desc demo_txn; /* Name Null? Type ----- -------- ------------------- TS TIMESTAMP(6) VAL NOT NULL NUMBER */ 1. Implicit COMMIT on normal SQL*Plus exit insert into demo_txn(ts,val) values(systimestamp,1); exit Reconnect: select * from demo_txn; -- one row committed autom...
Redo Logging Modes Overview Redo logging controls how much information Oracle writes to on line redo log files during data changes. Three principal modes exist: LOGGING: Default mode where all DML and object creation actions generate redo entries. Suitable for most database objects; NOLOGGING is gen...
Prerequisites and Environment Setup To enable SSL access for an Oracle database, you need a functioning server and client environment. In this example: Server: CentOS 7.9 running Oracle Database 11.2.0.4.0 Client: Windows Server 2008 R2 running Oracle Client 11.2.0.3.0 Start by creating wallets and...