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My friend has asked this question today as he got the same in one his interview… The common answer we give is from any base table as v$database (current_scn) is populated by any base table. However the base table is $KCCDI under column DICUR_SCN is current SCN. you can find this by querying the v$database […] The key difference Guaranteed restore point does not need explicitly flashback on, where in the normal restore point does Guaranteed restore point requires less I/O as compared to the normal restore point due to the fact that flashback log maintains only one copy of block image before it get modified. where in the normal […] A user has posted me "how to find the fragmentation for a table that contains CLOB", ironically all the queries and other stuff will lead to confusion or no more useful. Honestly, to answer this question I have searched many things to clear up, only Jonathan has a clear cut demonstration and answer for […] Starting/Stopping CDB and PDBs The traditional approach of starting and stopping databases is now only valid for CDB. So in order to start and stop CDB you will use the familiar startup and shutdown commands. PDBs don’t get automatically started with CDB. Even if your CDB is up and running it is possible […] Create & Plug and Unplug PDB’s To Create PDB’s the following methods can be followed Copying From PDB Seed Cloning from a existing PDB using Locally Remotely through DB Link Plugging in Plugging in an unplugged DB (unplug and plug as database into same container database) Plugging in a NON-CDB as […] From 12c onwards, Oracle 12c introduced truncate with cascade so when truncate operates on master table the child table rows also get truncated automatically. SCOTT@PDB > create table MASTER ( 2 ID number generated always as identity PRIMARY KEY, 3 NAME VARCHAR2(20) 4 ); Table created. SCOTT@PDB > create table CHILD ( 2 ID […] RMAN backup scenarios in 12c, With the advent of 12c PDB/CDB rman backup has changed a lot while taking backups or restoration. Backups on PDB or CDB “BACKUP PLUGGABLE DATABASE” – To take backups for a pluggable database “BACKUP DATABASE” – “BACKUP DATABASE;” on root container backs up the whole container includes SEED Container […] From 12c onwards we have seperate roles to be created for OS Authentication Prior to 12c we have OSDBA, OSOPER, OSASM, OSDBA, OSOPER groups From 12c onwards, OSBACKUPDBA maps to backupdba by default and is used to allow users to backup the database. Users in this group can connect as SYSBACKUP and have their […] From Oracle 10g, the Oracle SMON (System Monitor) process regularly gathers information on columns that are used in query predicates and updates them automatically into a table named COL_USAGE$ in the SYS schema. Unlike the MON_MOD$ table, also in the SYS schema, which records table-level DML activity such as the number of rows changed by […] In a container architecture, the parameters for PDB will inherit from the root database. That means if statistics_level=all in the root that will cascade to the PDB databases. You can over ride this by using Alter system set, if that parameter is pdb modifiable, there is a new column in v$system_parameter for the same. The […] |
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Oracle 23c New Features for DBA's
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