Oracle database knowledge has been organized into 12 articles so far. This is not the end, but rather a beginning. I hope my articles can help beginners get started with databases more quickly. If you find these articles helpful, congratulations on your entry into the world of databases! There's so...
Testing Environment Source Database: Windows 7 64-bit, Oracle 11g 64-bit Target Database: RHEL6 64-bit, Oracle 11g 64-bit 1. Check Data base Character Set select * from nls_database_parameters; select userenv('language') from dual; 2. Review Transportable Platform Options SELECT * FROM v$transportab...
pfile and spfile Overview Oracle stores initialization parameters in configuration files that are loaded during instance startup. These files define the database's physical structure, memory allocation, system constraints, and various default values. Oracle supports two types of parameter files: pfi...
Physical Reads (Physical Reads) Physical reads occur when data blocks are read from disk into memory. This happens when the required data block are not present in the SGA's cache buffer. Operations like full table scans or disk sorting may also trigger physical reads due to the large volume of data...
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...