Modify oracle sys password

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

Run SELECT*FROMv$version; you can obtain the complete version information of the Oracle database, including the database, PL/SQL, core library, etc. version details, which is the most commonly used reliable method for DBA; 2. Use SELECTbannerFROMv$versionWHEREbannerLIKE'Oracle%'; you can only display the main version information of the Oracle database; 3. Query the PRODUCT_COMPONENT_VERSION view to get the version of each Oracle component; 4. Through the sqlplus-V command, you can view the client or server tool version without logging into the database, but it may not reflect the actual running

OracleFlashbacktechnologyoffersmultiplerecoveryoptionstoaddresslogicalerrorswithminimaldowntime.1.FlashbackDatabaseallowsrollingbacktheentiredatabaseusingflashbacklogsintherecoveryareatoaspecificpointintime.2.FlashbackTablerecoversindividualtablesaff

BULKCOLLECT and FORALL significantly improve PL/SQL performance by reducing context switching. 1. BULKCOLLECT batch-in-batch data to the set at one time to avoid frequent switching caused by line-by-line acquisition; 2. FORALL sends the DML operations of the set to the SQL engine for processing at one time, replacing inefficient loop execution one by one; 3. The combination of the two can realize efficient data extraction, processing and update, and is suitable for ETL, batch tasks and other scenarios; 4. When using it, pay attention to controlling the set size, rationally use LIMIT batch processing, and avoid adding complex conditional logic to FORALL.

InOracle’slogicalstoragehierarchy,segments,extents,andblocksformastructuredframeworkfordatastorage.Datablocksarethesmalleststorageunit,typically8KBinsize,whereactualdataliketablerowsorindexentriesarestored.Extentsconsistofcontiguousdatablocksallocate

PL/SQL collections are used to store multiple values in a single variable. There are three main types: 1. Associative arrays (Index-By tables) are suitable for temporary storage in PL/SQL blocks, such as cache error messages or configuration settings, and can be directly assigned without initialization and indexes can start from any number; 2. Nested tables are supported for storage in database tables and used in SQL statements, suitable for passing data sets or storing structured lists, expandable and support DML operations; 3. Varrays are used for ordered, fixed-size lists, such as week or month, and the maximum capacity needs to be defined. The inline performance is good during storage but a single element cannot be deleted. Which type to choose depends on whether the specific application scenario involves storing, passing or temporarily using data.

OraclesupportsJSONdatatypesandoperationssinceOracle12c,enablingefficientstorage,querying,andmanipulationofsemi-structureddatawithinarelationalSQLenvironment.1.JSONdataisstoredusingVARCHAR2,CLOB,orBLOBtypeswithacheckconstraint(ISJSON)toensurevalidity.

TheOracleOptimizerdeterminesthemostefficientwaytoexecuteSQLbyanalyzingexecutionplansbasedonstatisticsandcostestimation.1.Itdecideshowtoaccessdata,includingindexusage,tablejoinorder,andjoinmethods.2.Itestimatescostusingtableandsystemstatistics,andpred