Answer Credit:- https://www.linkedin.com/in/skantali/ https://www.linkedin.com/in/hemant-shahi-59921762/ How we can execute PLSQL without any privilege to change it What are the default user created when Oracle is installed ? Can you create password less user in Oracle ? If yes how ? How we can see the procedure /package body with out having privilege to execute it How we can create password file […]
What is PGA The Program Global Area (PGA) is a private memory region that contains the data and control information for a server process. Only a server process can access the PGA. Oracle Database reads and writes information in the PGA on behalf of the server process. An example of such information is the run-time area of a cursor. Each […]
What are base tables? When and how they will get created? Ans:-Are read-only tables(Data Dictionary Tables) that hold information about the database. Base tables are own by SYS. When and how they will get created? They get created when the database is built. https://docs.oracle.com/cd/B19306_01/server.102/b14220/datadict.htm Why to execute catproc.sql script? Ans:-Used to create and recreate database internal views/procedures/packagess. Primarily used after […]
1.What are new features of datapump in 12c? https://oracle-base.com/articles/12c/data-pump-enhancements-12cr1 2.which case we need to use flashback_time or flashback_scn parameter? If you need consistent backup for example when you do initial load using datapump for golden gate. 3.During impdp with full=y caluse , do we need to create user before import? No.User will be automatically created. 4.which memory area expdp and […]
Listener related questions:- Answer Credit:- https://www.linkedin.com/in/saibal-ghosh-ccsk-prince2-%C2%AE-469b0a7/ 1.Can we manually force a particular scan ip (out of the three) to relocate on a particular host (lets say – on node 5 of 5 node RAC) ? Ans:- srvctl relocate scan_LISTENER -i 1 -n node1 $ srvctl relocate scan -h Usage: srvctl relocate scan -i <ordinal_number> [-n <node_name>] -i <scan_ordinal_number> Ordinal number […]
Clustering Factor and it’s effect on non-assm and assm tablespace. The clustering factor is a measure of the ordernesss of an index in comparison to the table that it is based on. It is used to check the cost of a table lookup following an index access (multiplying the clustering factor by the index’s selectivity gives you the cost of […]
A. B-Tree Indexes I have discussed more details in the below blog. http://clouddba.co/index-internal-oracle-using-simple-test-case/ B.Invisible Indexes Deciding which columns to index is hard. The primary key is automatically indexed, the foreign keys should also be indexed, but then what? Even more difficult is deciding which index to remove that might be a bad index. Every time a record is inserted, all […]
Index internal oracle using simple test case First of all I will create a table with char(1000) so that in one block I can fit 6-7 entries . Here are some relevant notes regarding Index split For Leaf block kdxlespl: bytes of uncommitted data at time of block split that have been cleaned out kdxlende: number of deleted entries kdxlenxt: […]
How histogram can affect query plan change hence performance. 1.Let me create a test case.I am loading the table with following distribution.Obviously it means data is somewhat skewed. Value:-1 Range:-10 Value:-2 Range:-100 Value:-3 Range:-1000 Value:-4 Range:-10000 Value:-5 Range:-100000 C##TEST@TESTDB1> create table tt1(c1 number,c2 char(10)); Table created. C##TEST@TESTDB1> declare begin for j in 1..10 loop 2 3 4 insert into tt1 […]
1.Let us create a test case first:- oracle@TST:TESTDB1[/home/oracle]$ sqlplus c##test/test C##TEST@TESTDB1> create table mytst1 as select * from dba_objects; Table created. C##TEST@TESTDB1> create table mytst2 as select * from dba_objects where rownum<5000; Table created. 2.Let us see what application executes SQL query and complaining poor performance select a.owner,a.OBJECT_NAME,a.OBJECT_TYPE,b.STATUS from mytst1 a,mytst2 b where a.OBJECT_ID=b.OBJECT_ID and b.OBJECT_NAME=’DBA_TABLES’; 3.Now create an index […]