Oracle PGA (Program Global Area) in 12c

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-timeContinue reading Oracle PGA (Program Global Area) in 12c

Index in 12c by example test case

A. B-Tree Indexes I have discussed more details in the below blog. 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 mightContinue reading Index in 12c by example test case

Index internal oracle using simple 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 have been cleaned out kdxlende:Continue reading Index internal oracle using simple test case

Undo Advisor help to estimate the undo tablespace size and undo retention to avoid ORA-1555

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 ———————————— ———– —————————— undo_management                      string      AUTO undo_retention             Continue reading Undo Advisor help to estimate the undo tablespace size and undo retention to avoid ORA-1555

How to check and implement best practice for Oracle Database 11g onwards

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 the Oracle Database Cloud space,Continue reading How to check and implement best practice for Oracle Database 11g onwards

FLASHBACK DATABASE AND QUERIES

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;   ———–Accidentaly Delete——————————————   Accidentally droppedContinue reading FLASHBACK DATABASE AND QUERIES

Network configuration listener and tnsnames in oracle

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 an Oracle installation and instanceContinue reading Network configuration listener and tnsnames in oracle

Memory and Process in Oracle generic note

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 Shared Memory Sometimes after anContinue reading Memory and Process in Oracle generic note