General DBACategory

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… Continue Reading Oracle PGA (Program Global Area) in 12c

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… Continue Reading Index in 12c by example test case

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… Continue Reading Index internal oracle using simple test case

Prepare by: Nurullah Sharif Scope: Undo Advisor   Undo Advisor help to estimate the undo tablespace size and also advise of undo retention. SQL> @db NAME      OPEN_MODE ——— ——————– COLLPROD  READ WRITE   Undo retention is 900 sec which 15 min SQL> sho parameter undo NAME                                 TYPE        VALUE ———————————— ———–… Continue Reading Undo Advisor help to estimate the undo tablespace size and undo retention to avoid ORA-1555

Author: Saibal Ghosh About author: I am an Oracle professional with twenty plus years of experience and have deep knowledge and understanding of various facets of Oracle technology including basic Oracle Database Administration, Performance Tuning, Real Application Clusters, Data Guard and Maximum Availability Architecture. I also work a lot in… Continue Reading How to check and implement best practice for Oracle Database 11g onwards

FLASHBACK FEATURES   Purging the Recycle Bin   purge table sales.woodscrews; purge index sales.woodscrews_pk_idx; purge tablespace sales; purge recyclebin;   Undropping Objects in the Recycle Bin   flashback table ws_app.woodscrews to before drop; select object_name, original_name, droptime, dropscn from user_recyclebin; flashback table bonus to before drop rename to bonus_deb;  … Continue Reading FLASHBACK DATABASE AND QUERIES

Oracle Network Configuration =========================== In its most basic form, Oracle uses three files (listener.ora, tnsnames.ora & sqlnet.ora) for network configuration. This article gives an example of each file as a starting point for simple network configuration. •Assumptions •Listener.ora •Tnsnames.ora •Sqlnet.ora •Testing Assumptions ========== The example files below are relevant for… Continue Reading Network configuration listener and tnsnames in oracle

MEMORY MANAGEMENT 11g ===================== http://blog.tanelpoder.com/2007/08/21/oracle-11g-internals-part-1-automatic-memory-management/ PGA+SGA=MEMORY_TARGET what are the shared memory IDs for my instance $ sysresv corresponding SysV SHM segments: $ ipcs -m mapped memory for an Oracle instance process – as the SGA should be definitely mapped there! $ pmap `pgrep -f lgwr` $ ls -l /dev/shm Removing… Continue Reading Memory and Process in Oracle generic note

What Is a Control File? Every Oracle database has a control file. A control file is a small binary file that records the physical structure of the database and includes: n The database name n Names and locations of associated datafiles and online redo log files n The timestamp of… Continue Reading control files in general