Let's talk about Oracle storage process

OracleSGA is composed of multiple key components, each of which undertakes different functions: 1. DatabaseBufferCache is responsible for caching data blocks to reduce disk I/O and improve query efficiency; 2. RedoLogBuffer records database changes to ensure transaction persistence and recovery capabilities; 3. SharedPool includes LibraryCache and DataDictionaryCache, which is used to cache SQL parsing results and metadata; 4. LargePool provides additional memory support for RMAN, parallel execution and other tasks; 5. JavaPool stores Java class definitions and session objects; 6. StreamsPool is used for Oracle

Yes,AWRandADDMreportsareessentialforOracleperformancetuning.1.AWRreportsprovidesnapshotsofdatabaseactivity,showingtopSQL,waitevents,resourceusage,andtrendsovertime—usefulforidentifyinginefficientqueriesandcacheeffectiveness.2.ADDManalyzesAWRdatatodet

SQLPlanManagement(SPM)ensuresstablequeryperformancebypreservingknowngoodexecutionplansandallowingonlyverifiedplanstobeused.1.SPMcapturesandstoresexecutionplansinSQLplanbaselines.2.Newplansarecheckedagainstthebaselineandnotusedunlessprovenbetterorsafe

Oracle automatically handles conversions between different character sets, but if the target character set cannot represent characters in the source character set, data loss or replacement may occur. Its core mechanism is to use the built-in conversion engine for character mapping, which is often when the client and the database NLS_LANG settings are inconsistent, cross-database transmission, or use the CONVERT() function. Key considerations include: 1. Use AL32UTF8 as the database character set to support Unicode; 2. Properly configure the client NLS_LANG; 3. Use NVARCHAR2 and NCLOB to store multilingual data; 4. Use CSSCAN tools to detect potential problems before migration; 5. Beware of LENGTH(), SUBSTR() and other functions

NLS\_LANG settings errors will cause garbled data or format errors. It contains three elements: language, region and character set. It should be ensured that the character set of the client and the database match. It is recommended to use AL32UTF8 to support Unicode, and control session-level parameters through ALTERSESSION. At the same time, configure environment variables or Windows registry in Unix/Linux to correctly apply the settings. Specific key points include: 1.NLS\_LANG determines message translation, date currency format and character encoding conversion; 2. The client character set must be compatible with the database, otherwise it will cause data corruption; 3. Avoid automatic conversion and test special characters; 4. Other NLS parameters such as NLS\_DATE\_FOR

Storedprocedures,functions,andpackagesinPL/SQLimprovecodemodularityandreusabilitybyencapsulatinglogic,promotingcentralizedmaintenance,andorganizingrelatedcomponents.1.Storedprocedurescentralizebusinesslogicintocallableunits,reducingredundancyandsimpl

SID is an instance-level identifier used to identify specific database instances, such as ORCL or TESTDB, suitable for old tools, local connections and single-instance environments; service name is a service-level logical identifier, such as sales.example.com, which supports high availability architectures such as RAC and DataGuard, and has stronger flexibility. It is recommended for new connections and client configurations. Both can be defined in tnsnames.ora, but the service name is more suitable for the contemporary database environment, ensuring future compatibility and convenient maintenance.

Oracle deadlock occurs when two or more sessions wait for each other to release resource locks, forming a circular dependency. For example: 1. After session A updates line 1, try to update line 2; 2. After session B updates line 2, try to update line 1. If it runs at the same time, it will block each other to form a deadlock. Oracle automatically detects and rolls back one of the transactions to break the deadlock, which receives an ORA-00060 error. Other common reasons include not committing transactions holding row-level locks, improper index usage causes lock upgrades, and application logic allows out-of-order overlapping updates. The detection methods include viewing deadlock records in the alert log, tracking files, and querying V$LOCKED_OBJECT and V$SESSION views. The solution is to analyze and track files and ensure transactions