Oracle® Advanced Replication Example

This is one in the list of my Example Series in this blog. Check this blog for more possible examples

I was asked questions relating Replication in 10g.

As usual, I thought I should answer the question by using examples. This is following steps using the examples in the following links. I have chosen to use 2 Master sites instead of the 3 in the document.

Create Replication Site
Create a Master Group
Monitoring a Replication Environment


I used 10g Release 10.1 document because it was the first one I picked, but you can use the 10g Release 10.2 document.

Note: I have not hidden my passwords because it is my stand-alone test on a Laptop. I do not recommend exposing your passwords on the system.

This test as mentioned in the documentation assumes that the HR example schema has been created on both databases using the same script/structure. You will find the scripts under $ORACLE_HOME/demo/schema.

This shows the results of the examples and should be read with the document in the above links.

-- Setup Master Site Database TESTDB – This Database is on a different ORACLE_HOME on same Test Laptop as EMREP1. Oracle 10g Realease 10.2.0.2

Step 1 Connect as SYSTEM at a master site TESTDB

SQL> connect system/oracl3
Connected.

SQL>

Step 2 Create the replication administrator at TESTDB

SQL> CREATE USER repadmin IDENTIFIED BY repadmin;

User created.

SQL>

Step 3 Grant privileges to the replication administrator at TESTDB

SQL> BEGIN
2 DBMS_REPCAT_ADMIN.GRANT_ADMIN_ANY_SCHEMA (
3 username => 'repadmin');
4 END;
5 /

PL/SQL procedure successfully completed.

SQL>
SQL> GRANT COMMENT ANY TABLE TO repadmin;

Grant succeeded.

SQL> GRANT LOCK ANY TABLE TO repadmin;

Grant succeeded.

SQL> GRANT SELECT ANY DICTIONARY TO repadmin;

Grant succeeded.

SQL>

Step 4 Register the propagator at TESTDB

SQL> BEGIN
2 DBMS_DEFER_SYS.REGISTER_PROPAGATOR (
3 username => 'repadmin');
4 END;
5 /

PL/SQL procedure successfully completed.

SQL>

Step 5 Register the receiver at TESTDB

SQL> BEGIN
2 DBMS_REPCAT_ADMIN.REGISTER_USER_REPGROUP (
3 username => 'repadmin',
4 privilege_type => 'receiver',
5 list_of_gnames => NULL);
6 END;
7 /

PL/SQL procedure successfully completed.

SQL>

Step 6 Schedule purge at master site TESTDB

SQL> CONNECT repadmin/repadmin
Connected.
SQL> BEGIN
2 DBMS_DEFER_SYS.SCHEDULE_PURGE (
3 next_date => SYSDATE,
4 interval => 'SYSDATE + 1/24',
5 delay_seconds => 0);
6 END;
7 /

PL/SQL procedure successfully completed.

SQL>

Step 7 Create proxy master site users at TESTDB

SQL> connect system/oracl3
Connected.
SQL> CREATE USER proxy_mviewadmin IDENTIFIED BY proxy_mviewadmin;

User created.

SQL> BEGIN
2 DBMS_REPCAT_ADMIN.REGISTER_USER_REPGROUP (
3 username => 'proxy_mviewadmin',
4 privilege_type => 'proxy_snapadmin',
5 list_of_gnames => NULL);
6 END;
7 /

PL/SQL procedure successfully completed.

SQL> GRANT SELECT_CATALOG_ROLE TO proxy_mviewadmin;

Grant succeeded.

SQL> CREATE USER proxy_refresher IDENTIFIED BY proxy_refresher;

User created.

SQL> GRANT CREATE SESSION TO proxy_refresher;

Grant succeeded.

SQL> GRANT SELECT ANY TABLE TO proxy_refresher;

Grant succeeded.

SQL>

-- Setup Master Site Database EMREP1 – This Database is on a different ORACLE_HOME on same Test Laptop as TESTDB. Oracle 10g Realease 10.1.0.4

Step 1 Connect as SYSTEM at a master site EMREP1

SQL> conn system/oracl3
Connected.

SQL>

Step 2 Create the replication administrator at EMREP1

SQL> create user REPADMIN identified by REPADMIN;

User created.

SQL>

Step 3 Grant privileges to the replication administrator at EMREP1

SQL> BEGIN
2 DBMS_REPCAT_ADMIN.GRANT_ADMIN_ANY_SCHEMA (
3 username => 'repadmin');
4 END;
5 /

PL/SQL procedure successfully completed.

SQL> GRANT COMMENT ANY TABLE TO repadmin;

Grant succeeded.

SQL> GRANT LOCK ANY TABLE TO repadmin;

Grant succeeded.

SQL>
SQL> GRANT SELECT ANY DICTIONARY TO repadmin;

Grant succeeded.

SQL>

Step 4 Register the propagator at EMREP1

SQL> BEGIN
2 DBMS_DEFER_SYS.REGISTER_PROPAGATOR (
3 username => 'repadmin');
4 END;
5 /

PL/SQL procedure successfully completed.

SQL>

Step 5 Register the receiver at EMREP1

SQL> BEGIN
2 DBMS_REPCAT_ADMIN.REGISTER_USER_REPGROUP (
3 username => 'repadmin',
4 privilege_type => 'receiver',
5 list_of_gnames => NULL);
6 END;
7 /

PL/SQL procedure successfully completed.

SQL>

Step 6 Schedule purge at master site EMREP1

SQL> CONNECT repadmin/repadmin
Connected.
SQL> BEGIN
2 DBMS_DEFER_SYS.SCHEDULE_PURGE (
3 next_date => SYSDATE,
4 interval => 'SYSDATE + 1/24',
5 delay_seconds => 0);
6 END;
7 /

PL/SQL procedure successfully completed.

SQL>

Step 7 Create proxy master site users at EMREP1

SQL> conn system/oracl3
Connected.
SQL> CREATE USER proxy_mviewadmin IDENTIFIED BY proxy_mviewadmin;

User created.

SQL> BEGIN
2 DBMS_REPCAT_ADMIN.REGISTER_USER_REPGROUP (
3 username => 'proxy_mviewadmin',
4 privilege_type => 'proxy_snapadmin',
5 list_of_gnames => NULL);
6 END;
7 /

PL/SQL procedure successfully completed.

SQL>
SQL> GRANT SELECT_CATALOG_ROLE TO proxy_mviewadmin;

Grant succeeded.

SQL> CREATE USER proxy_refresher IDENTIFIED BY proxy_refresher;

User created.

SQL>
SQL> GRANT CREATE SESSION TO proxy_refresher;

Grant succeeded.

SQL> GRANT SELECT ANY TABLE TO proxy_refresher;

Grant succeeded.

SQL>


-- Create Scheduled Links Between Master Sites at TESTDB

Step 1 Create database links between master sites

SQL> CONNECT SYSTEM/oracl3
Connected.
SQL> CREATE PUBLIC DATABASE LINK emrep1 USING 'emrep1';

Database link created.

SQL> CONNECT repadmin/repadmin
Connected.
SQL> CREATE DATABASE LINK emrep1 CONNECT TO repadmin IDENTIFIED BY repadmin;

Database link created.

SQL>

Step 2 Define a schedule for each database link to create scheduled links

SQL> CONNECT repadmin/repadmin
Connected.
SQL>
SQL> BEGIN
2 DBMS_DEFER_SYS.SCHEDULE_PUSH (
3 destination => 'emrep1',
4 interval => 'SYSDATE + (1/144)',
5 next_date => SYSDATE,
6 parallelism => 1,
7 execution_seconds => 1500,
8 delay_seconds => 1200);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>

-- Create Scheduled Links Between Master Sites at EMREP1

Step 1 Create database links between master sites

SQL> CONNECT SYSTEM/oracl3
Connected.
SQL> CREATE PUBLIC DATABASE LINK testdb USING 'testdb';

Database link created.

SQL>
SQL> CONNECT repadmin/repadmin
Connected.
SQL> CREATE DATABASE LINK testdb CONNECT TO repadmin IDENTIFIED BY repadmin;

Database link created.

SQL>

Step 2 Define a schedule for each database link to create scheduled links

SQL> CONNECT repadmin/repadmin
Connected.
SQL>
SQL> BEGIN
2 DBMS_DEFER_SYS.SCHEDULE_PUSH (
3 destination => 'testdb',
4 interval => 'SYSDATE + (1/144)',
5 next_date => SYSDATE,
6 parallelism => 1,
7 execution_seconds => 1500,
8 delay_seconds => 1200);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>



-- Create Master Group in TESTDB

Step 1 Create the schema at master sites at TESTDB

SQL> SET ECHO ON
SQL>
SQL> SPOOL create_mg.out
SQL>
SQL> CONNECT repadmin/repadmin
Connected.
SQL> PAUSE Press to continue when the schema exists at all master sites.
Press to continue when the schema exists at all master sites.
SQL>

Step 2 Create the master group at TESTDB

SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPGROUP (
3 gname => 'hr_repg');
4 END;
5 /

PL/SQL procedure successfully completed.

SQL>

Step 3 Add objects to master group at TESTDB

SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'countries',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL> BEGIN
SQL> DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
SQL> gname => 'hr_repg',
SQL> type => 'TABLE',
SQL> oname => 'countries',
SQL> sname => 'hr',
SQL> use_existing_object => TRUE,
SQL> copy_rows => FALSE);
SQL> END;
SQL> /
SQL> */
SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'departments',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'employees',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'jobs',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'job_history',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'locations',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'TABLE',
5 oname => 'regions',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'dept_location_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'emp_department_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'emp_job_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'emp_manager_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'jhist_department_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'jhist_employee_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'jhist_job_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.CREATE_MASTER_REPOBJECT (
3 gname => 'hr_repg',
4 type => 'INDEX',
5 oname => 'loc_country_ix',
6 sname => 'hr',
7 use_existing_object => TRUE,
8 copy_rows => FALSE);
9 END;
10 /

PL/SQL procedure successfully completed.

SQL>

Step 4 Add additional master site for EMREP1 at TESTDB

SQL> BEGIN
2 DBMS_REPCAT.ADD_MASTER_DATABASE (
3 gname => 'hr_repg',
4 master => 'emrep1',
5 use_existing_objects => TRUE,
6 copy_rows => FALSE,
7 propagation_mode => 'ASYNCHRONOUS');
8 END;
9 /

PL/SQL procedure successfully completed.

SQL>

Step 5 If conflicts are possible, then configure conflict resolution methods

SQL>

SQL> PAUSE Press to continue after configuring conflict resolution methods
Press to continue after configuring conflict resolution methods
or if no conflict resolution methods are required.

SQL>

Step 6 Generate replication support at TESTDB

SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'countries',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'departments',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'employees',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'jobs',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'job_history',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'locations',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL> BEGIN
2 DBMS_REPCAT.GENERATE_REPLICATION_SUPPORT (
3 sname => 'hr',
4 oname => 'regions',
5 type => 'TABLE',
6 min_communication => TRUE);
7 END;
8 /

PL/SQL procedure successfully completed.

SQL>
SQL>
SQL>
SQL> SELECT COUNT(*) FROM DBA_REPCATLOG WHERE GNAME = 'HR_REPG';

COUNT(*)
----------
0

SQL>

Step 7 Start replication at TESTDB

SQL> BEGIN
2 DBMS_REPCAT.RESUME_MASTER_ACTIVITY (
3 gname => 'hr_repg');
4 END;
5 /

PL/SQL procedure successfully completed.

SQL>

-- Monitor Replication Environment

SQL> SELECT DBLINK FROM DBA_REPSITES WHERE GNAME = 'HR_REPG';

DBLINK
--------------------------------------------------------------------------------
EMREP1
TESTDB

SQL>
SQL> COLUMN GLOBAL_NAME HEADING 'Database' FORMAT A25
SQL> COLUMN ADMIN_REQUESTS HEADING 'AdminReqests' FORMAT 9999
SQL> COLUMN STATUS HEADING 'AdminErrors' FORMAT 9999
SQL> COLUMN TRAN HEADING 'DefTransPairs' FORMAT 9999
SQL> COLUMN ERRORS HEADING 'DefTransErrors' FORMAT 9999
SQL> COLUMN COMPLETE HEADING 'PropagatedTrans' FORMAT 9999
SQL> SELECT G.GLOBAL_NAME, D.ADMIN_REQUESTS, E.STATUS, DT.TRAN, DE.ERRORS, C.COMPLETE
2 FROM (SELECT GLOBAL_NAME FROM GLOBAL_NAME) G,
3 (SELECT COUNT(ID) ADMIN_REQUESTS FROM DBA_REPCATLOG) D,
4 (SELECT COUNT(STATUS) STATUS FROM DBA_REPCATLOG WHERE STATUS = 'ERROR') E,
5 (SELECT COUNT(*) TRAN FROM DEFTRANDEST) DT,
6 (SELECT COUNT(*) ERRORS FROM DEFERROR) DE,
7 (SELECT COUNT(A.DEFERRED_TRAN_ID) COMPLETE FROM DEFTRAN A
8 WHERE A.DEFERRED_TRAN_ID NOT IN (
9 SELECT B.DEFERRED_TRAN_ID FROM DEFTRANDEST B)) C;

Def Def
Admin Admin Trans Trans Propagated
Database Reqests Errors Pairs Errors Trans
------------------------- ------- ------ ----- ------ ----------
TESTDB 0 0 0 0 0

SQL> COLUMN GNAME HEADING 'Master Group' FORMAT A20
SQL> COLUMN DBLINK HEADING 'Sites' FORMAT A25
SQL> COLUMN MASTERDEF HEADING 'MasterDefinitionSite?' FORMAT A10
SQL> SELECT GNAME, DBLINK, MASTERDEF
2 FROM DBA_REPSITES
3 WHERE MASTER = 'Y'
4 AND GNAME NOT IN (SELECT GNAME FROM DBA_REPSITES WHERE SNAPMASTER = 'Y')
5 ORDER BY GNAME;

Master
Definition
Master Group Sites Site?
-------------------- ------------------------- ----------
HR_REPG EMREP1 N
HR_REPG TESTDB Y

SQL> COLUMN GNAME HEADING 'Master Group' FORMAT A15
SQL> COLUMN deftran HEADING 'Number ofDeferredTransactionPairs' FORMAT 9999
SQL> COLUMN deftranerror HEADING 'Number ofDeferredTransactionErrors' FORMAT 9999
SQL> COLUMN adminreq HEADING 'Number ofAdministrativeRequests' FORMAT 9999
SQL> COLUMN adminreqerror HEADING 'Number ofAdministrativeRequestErrors'
SQL> COLUMN adminreqerror FORMAT 9999
SQL>
SQL> SELECT G.GNAME,
2 NVL(T.CNT1, 0) deftran,
3 NVL(IE.CNT2, 0) deftranerror,
4 NVL(A.CNT3, 0) adminreq,
5 NVL(B.CNT4, 0) adminreqerror
6 FROM
7 (SELECT DISTINCT GNAME FROM DBA_REPGROUP WHERE MASTER='Y') G,
8 (SELECT DISTINCT RO.GNAME, COUNT(DISTINCT D.DEFERRED_TRAN_ID) CNT1
9 FROM DBA_REPOBJECT RO, DEFCALL D, DEFTRANDEST TD
10 WHERE RO.SNAME = D.SCHEMANAME
11 AND RO.ONAME = D.PACKAGENAME
12 AND RO.TYPE IN ('TABLE', 'PACKAGE', 'MATERIALIZED VIEW')
13 AND TD.DEFERRED_TRAN_ID = D.DEFERRED_TRAN_ID
14 GROUP BY RO.GNAME ) T,
15 (SELECT DISTINCT RO.GNAME, COUNT(DISTINCT E.DEFERRED_TRAN_ID) CNT2
16 FROM DBA_REPOBJECT RO, DEFCALL D, DEFERROR E
17 WHERE RO.SNAME = D.SCHEMANAME
18 AND RO.ONAME = D.PACKAGENAME
19 AND RO.TYPE IN ('TABLE', 'PACKAGE', 'MATERIALIZED VIEW')
20 AND E.DEFERRED_TRAN_ID = D.DEFERRED_TRAN_ID
21 AND E.CALLNO = D.CALLNO
22 GROUP BY RO.GNAME ) IE,
23 (SELECT GNAME, COUNT(*) CNT3 FROM DBA_REPCATLOG GROUP BY GNAME) A,
24 (SELECT GNAME, COUNT(*) CNT4 FROM DBA_REPCATLOG
25 WHERE STATUS = 'ERROR'
26 GROUP BY GNAME) B WHERE G.GNAME = IE.GNAME (+)
27 AND G.GNAME = T.GNAME (+)
28 AND G.GNAME = A.GNAME (+)
29 AND G.GNAME = B.GNAME (+) ORDER BY G.GNAME;

Number of Number of Number of
Deferred Deferred Number of Administrative
Transaction Transaction Administrative Request
Master Group Pairs Errors Requests Errors
--------------- ----------- ----------- -------------- --------------
HR_REPG 0 0 0 0


SQL> COLUMN repgroup HEADING 'Number ofReplicationGroups' FORMAT 9999
SQL> COLUMN mvgroup HEADING 'Number ofRegisteredMV Groups' FORMAT 9999
SQL> COLUMN mv HEADING 'Number ofRegistered MVs' FORMAT 9999
SQL> COLUMN mvlog HEADING 'Number ofMV Logs' FORMAT 9999
SQL> COLUMN template HEADING 'Number ofTemplates' FORMAT 9999
SQL> SELECT A.REPGROUP repgroup,
2 B.MVGROUP mvgroup,
3 C.MV mv,
4 D.MVLOG mvlog,
5 E.TEMPLATE template
6 FROM (SELECT COUNT(G.GNAME) REPGROUP
7 FROM DBA_REPGROUP G, DBA_REPSITES S
8 WHERE G.MASTER = 'Y'
9 AND S.MASTER = 'Y'
10 AND G.GNAME = S.GNAME
11 AND S.MY_DBLINK = 'Y') A,
12 (SELECT COUNT(*) MVGROUP
13 FROM DBA_REGISTERED_MVIEW_GROUPS) B,
14 (SELECT COUNT(*) MV
15 FROM DBA_REGISTERED_MVIEWS) C,
16 (SELECT COUNT(*) MVLOG
17 FROM (SELECT 1 FROM DBA_MVIEW_LOGS
18 GROUP BY LOG_OWNER, LOG_TABLE)) D,
19 (SELECT COUNT(*) TEMPLATE FROM DBA_REPCAT_REFRESH_TEMPLATES) E;

Number of Number of
Replication Registered Number of Number of Number of
Groups MV Groups Registered MVs MV Logs Templates
----------- ---------- -------------- --------- ---------
1 0 2 0 0

SQL> COLUMN LOG_TABLE HEADING 'Log Table' FORMAT A20
SQL> COLUMN LOG_OWNER HEADING 'LogOwner' FORMAT A5
SQL> COLUMN MASTER HEADING 'Master' FORMAT A15
SQL> COLUMN ROWIDS HEADING 'RowID?' FORMAT A3
SQL> COLUMN PRIMARY_KEY HEADING 'PrimaryKey?' FORMAT A7
SQL> COLUMN OBJECT_ID HEADING 'ObjectID?' FORMAT A6
SQL> COLUMN FILTER_COLUMNS HEADING 'FilterColumns?' FORMAT A8
SQL>
SQL> SELECT DISTINCT LOG_TABLE,
2 LOG_OWNER,
3 MASTER,
4 ROWIDS,
5 PRIMARY_KEY,
6 OBJECT_ID,
7 FILTER_COLUMNS
8 FROM DBA_MVIEW_LOGS
9 ORDER BY 1;

no rows selected
SQL>

Hints:

To test that the replication setup works, try DML (Insert, Delete, Update) on any of the tables added as replication objects.

When using the HR example schema. After an update on Job table, you might get ORA-00001 UNIQUE CONSTRAINT VIOLATED error on the Job History table during replication, thereby causing the replication to fail. This is because of a trigger on Job table is trying to make a change that a replication is doing on Job history table in EMREP1 (in my example). A quick fix is to disable the trigger in EMREP1 (not in TESTDB in my example).

Using DBMS_METADATA in Procedure to reference another schema's object

This is a question already asked by many and I thought I should give an example here. You want to call DBMS_METADATA in PL/SQL created on your schema, but referencing another users object and use the the error like:

*
ERROR at line 1:
ORA-31603: object "EMP" of type TABLE not found in schema "SCOTT"
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 105
ORA-06512: at "SYS.DBMS_METADATA", line 2805
ORA-06512: at "SYS.DBMS_METADATA", line 4333
ORA-06512: at line 1
ORA-06512: at "TEST.TEST_META", line 5
ORA-06512: at line 1


It is an expected behviour which is stated in the security Model for dbms_metadata in the Oracle® Database PL/SQL Packages and Types Reference
.

The SELECT_CATALOG_ROLE alone does not give you privilege to use it in a package/procedure for another schema. But it allows you to use it outside.

So you need to use the invokers-right by adding authid current_user

Example:

SQL> connect test/test
Connected.
SQL> SELECT DBMS_METADATA.GET_DDL('TABLE', 'EMP', 'SCOTT') from dual;

DBMS_METADATA.GET_DDL('TABLE','EMP','SCOTT')
--------------------------------------------------------------------------------

CREATE TABLE "SCOTT"."EMP"
( "EMPNO" NUMBER(4,0),
"ENAME" VARCHAR2(10),

SQL> create or replace procedure test_meta
2 as
3 v_str varchar2(32767);
4 begin
5 SELECT DBMS_METADATA.GET_DDL('TABLE', 'EMP', 'SCOTT') into v_str from dual;
6 dbms_output.put_line (v_str);
7 end;
8 /

Procedure created.

SQL> exec test_meta;
BEGIN test_meta; END;

*
ERROR at line 1:
ORA-31603: object "EMP" of type TABLE not found in schema "SCOTT"
ORA-06512: at "SYS.DBMS_SYS_ERROR", line 105
ORA-06512: at "SYS.DBMS_METADATA", line 2805
ORA-06512: at "SYS.DBMS_METADATA", line 4333
ORA-06512: at line 1
ORA-06512: at "TEST.TEST_META", line 5
ORA-06512: at line 1

SQL> create or replace procedure test_meta authid current_user
2 as
3 v_str varchar2(32767);
4 begin
5 SELECT DBMS_METADATA.GET_DDL('TABLE', 'EMP', 'SCOTT') into v_str from dual;
6 dbms_output.put_line (v_str);
7 end;
8 /

Procedure created.

SQL> exec test_meta;

CREATE TABLE "SCOTT"."EMP"
( "EMPNO" NUMBER(4,0),
"ENAME" VARCHAR2(10),

"JOB" VARCHAR2(9),
"MGR" NUMBER(4,0),
"HIREDATE" DATE,
"SAL"
NUMBER(7,2),
"COMM" NUMBER(7,2),
"DEPTNO" NUMBER(2,0),
CONSTRAINT
"BIN$Bj5vCCIBT6uv5ZCEA/Zm0A==$0" PRIMARY KEY ("EMPNO")
USING INDEX PCTFREE 10
INITRANS 2 MAXTRANS 255
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL
DEFAULT)
TABLESPACE "USERS" ENABLE
) PCTFREE 10 PCTUSED 40 INITRANS 1
MAXTRANS 255 NOCOMPRESS LOGGING
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS
1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
BUFFER_POOL DEFAULT)
TABLESPACE "USERS" ENABLE ROW MOVEMENT


PL/SQL procedure successfully completed.

SQL>

Oracle® 11g Database Hints

I have finally installed Oracle® Database 11g Release 1 (11.1) for my testing. I will be sharing my experience with this post as I test and try to break it.


Platform: Windows XP SP2
Dell Latitude D810 Laptop
Intel Pentium M 2.0 GHz Processor
1GB RAM
60GB Hard Drive

Installation
My first install is for Windows. As usual, the Installation Guides from the Oracle® 11g Documentation Library was very helpul.

Installation Components
There are installation changes you may want to take note of. These include the addition of the following components: Oracle Application Express, Oracle Configuration Manager,Oracle Database Vault,Oracle Real Application Testing,Oracle SQL Developer and Oracle Warehouse Builder.

Pre installation checks - DHCP
The Pre installation check now includes checking and reporting if your machine has DHCP assigned IP Address. My System has a DHCP assigned IP Address. I got the warning, but ignored it because the IP assigned to me via DHCP is Reserved for my PC on our network. Reserved is not the same as Static.

Hardware Requirements

Physical memory: (RAM) 1 GB minimum
Virtual memory: Double the amount of RAM
Disk space: Basic Installation Type total: 4.55 GB
Disk space: Advanced Installation Types total: 4.92 GB
Video adapter: 256 colors
Processor: 550 MHz minimum (On Windows Vista, 800 MHz minimum)

Take note of the following hardware requirements. This is important because if you plan to installation with preconfigured database, you System might be so slow that you cannot start anything after the install because it will automatically start the database.

SPFILE

Below is some contents of my SPFILETEST11DB.ORA immediately after install, before I started changing it. So, looking at it, it is important that you have at least the 1GB RAM as recommended.

test11db.__db_cache_size=180355072
test11db.__java_pool_size=12582912
test11db.__large_pool_size=4194304
test11db.__oracle_base='C:\oracle'#ORACLE_BASE set from environment
test11db.__pga_aggregate_target=104857600
test11db.__sga_target=327155712
test11db.__shared_io_pool_size=0
test11db.__shared_pool_size=125829120
test11db.__streams_pool_size=0
*.audit_file_dest='C:\oracle\admin\test11db\adump'
*.audit_trail='db'
*.compatible='11.1.0.0.0'
*.db_block_size=8192
*.db_domain=''
*.db_name='test11db'
*.db_recovery_file_dest='C:\oracle\flash_recovery_area'
*.db_recovery_file_dest_size=2147483648
*.diagnostic_dest='C:\oracle'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=test11dbXDB)'
*.memory_target=428867584
*.open_cursors=300
*.processes=150
*.remote_login_passwordfile='EXCLUSIVE'
*.undo_tablespace='UNDOTBS1'


Deprecated Parameters

#background_dump_dest
#user_dump_dest

Deprecated Components

SQL*Plus Gui and iSQL*Plus is not included in the release
Enterprise Manager Java Console is not included in the release

Stanby Database

Oracle 11g allows you to use RMAN to change the db_unique_name of a Standby database using the CHANGE command CHANGE DB_UNIQUE_NAME FROM old_name to new_name. You can use this command after you have changed it in init parameter to update the recovery catalog.


Enterprise Manager Database Control
Also, the new look and feel of Enterprise Manager Console is an interesting. It is now grouped into the following tabs: Home, Performance, Availability, Server, Schema, Data Movement, Software and Support.

Why can I find my Database Tool in the EM Console?

Click my test images below.




EM Proxy and Browser Issues

I have Proxy settings on my Explorer. The bad news is that this is reset each time I log on to our Network. So, I have to change it not to proxy for my localhost, my servername and servername.domain.com. If I do not remember to do this, I keep getting Page Not found errors.

Note that this issue is not because of Oracle 11g. It is normal when you have to access any webserver related stuff on your PC and the browser has to go to the Proxy Server and back to yur PC. So whether it is 11g or 10g, you will get the same error.

Secured DB Console

I did a standard install using preconfigured setting. So by default, DB Console is secured. When I accessed with http, I kept getting a blank screen with squarea. I then checked my logs, changed the URL to use https and it worked.

Oracle® Demos for Scott Tiger

Ever thought of where to find those Oracle® demos for Scott Tiger ? I am posting it here because a lot of new Oracle Users can hardly find it. So you can pick it up here.

--
-- Copyright (c) Oracle Corporation 1988, 2000. All Rights Reserved.
--
-- NAME
-- demobld.sql
--
-- DESCRIPTION
-- This script creates the SQL*Plus demonstration tables in the
-- current schema. It should be STARTed by each user wishing to
-- access the tables. To remove the tables use the demodrop.sql
-- script.
--
-- USAGE
-- From within SQL*Plus, enter:
-- START demobld.sql

SET TERMOUT ON
PROMPT Building demonstration tables. Please wait.
SET TERMOUT OFF

DROP TABLE EMP;
DROP TABLE DEPT;
DROP TABLE BONUS;
DROP TABLE SALGRADE;
DROP TABLE DUMMY;

CREATE TABLE EMP
(EMPNO NUMBER(4) NOT NULL,
ENAME VARCHAR2(10),
JOB VARCHAR2(9),
MGR NUMBER(4),
HIREDATE DATE,
SAL NUMBER(7, 2),
COMM NUMBER(7, 2),
DEPTNO NUMBER(2));

INSERT INTO EMP VALUES
(7369, 'SMITH', 'CLERK', 7902,
TO_DATE('17-DEC-1980', 'DD-MON-YYYY'), 800, NULL, 20);
INSERT INTO EMP VALUES
(7499, 'ALLEN', 'SALESMAN', 7698,
TO_DATE('20-FEB-1981', 'DD-MON-YYYY'), 1600, 300, 30);
INSERT INTO EMP VALUES
(7521, 'WARD', 'SALESMAN', 7698,
TO_DATE('22-FEB-1981', 'DD-MON-YYYY'), 1250, 500, 30);
INSERT INTO EMP VALUES
(7566, 'JONES', 'MANAGER', 7839,
TO_DATE('2-APR-1981', 'DD-MON-YYYY'), 2975, NULL, 20);
INSERT INTO EMP VALUES
(7654, 'MARTIN', 'SALESMAN', 7698,
TO_DATE('28-SEP-1981', 'DD-MON-YYYY'), 1250, 1400, 30);
INSERT INTO EMP VALUES
(7698, 'BLAKE', 'MANAGER', 7839,
TO_DATE('1-MAY-1981', 'DD-MON-YYYY'), 2850, NULL, 30);
INSERT INTO EMP VALUES
(7782, 'CLARK', 'MANAGER', 7839,
TO_DATE('9-JUN-1981', 'DD-MON-YYYY'), 2450, NULL, 10);
INSERT INTO EMP VALUES
(7788, 'SCOTT', 'ANALYST', 7566,
TO_DATE('09-DEC-1982', 'DD-MON-YYYY'), 3000, NULL, 20);
INSERT INTO EMP VALUES
(7839, 'KING', 'PRESIDENT', NULL,
TO_DATE('17-NOV-1981', 'DD-MON-YYYY'), 5000, NULL, 10);
INSERT INTO EMP VALUES
(7844, 'TURNER', 'SALESMAN', 7698,
TO_DATE('8-SEP-1981', 'DD-MON-YYYY'), 1500, 0, 30);
INSERT INTO EMP VALUES
(7876, 'ADAMS', 'CLERK', 7788,
TO_DATE('12-JAN-1983', 'DD-MON-YYYY'), 1100, NULL, 20);
INSERT INTO EMP VALUES
(7900, 'JAMES', 'CLERK', 7698,
TO_DATE('3-DEC-1981', 'DD-MON-YYYY'), 950, NULL, 30);
INSERT INTO EMP VALUES
(7902, 'FORD', 'ANALYST', 7566,
TO_DATE('3-DEC-1981', 'DD-MON-YYYY'), 3000, NULL, 20);
INSERT INTO EMP VALUES
(7934, 'MILLER', 'CLERK', 7782,
TO_DATE('23-JAN-1982', 'DD-MON-YYYY'), 1300, NULL, 10);

CREATE TABLE DEPT
(DEPTNO NUMBER(2),
DNAME VARCHAR2(14),
LOC VARCHAR2(13) );

INSERT INTO DEPT VALUES (10, 'ACCOUNTING', 'NEW YORK');
INSERT INTO DEPT VALUES (20, 'RESEARCH', 'DALLAS');
INSERT INTO DEPT VALUES (30, 'SALES', 'CHICAGO');
INSERT INTO DEPT VALUES (40, 'OPERATIONS', 'BOSTON');

CREATE TABLE BONUS
(ENAME VARCHAR2(10),
JOB VARCHAR2(9),
SAL NUMBER,
COMM NUMBER);

CREATE TABLE SALGRADE
(GRADE NUMBER,
LOSAL NUMBER,
HISAL NUMBER);

INSERT INTO SALGRADE VALUES (1, 700, 1200);
INSERT INTO SALGRADE VALUES (2, 1201, 1400);
INSERT INTO SALGRADE VALUES (3, 1401, 2000);
INSERT INTO SALGRADE VALUES (4, 2001, 3000);
INSERT INTO SALGRADE VALUES (5, 3001, 9999);

CREATE TABLE DUMMY
(DUMMY NUMBER);

INSERT INTO DUMMY VALUES (0);

COMMIT;

SET TERMOUT ON
PROMPT Demonstration table build is complete.

EXIT

DBMS Direct at Oracle® Technology Network

I thought I should provide you with a link to find answers to some of the questions I have already answered or contributed to Oracle® Technology Network Forums.

Search My Oracle® Technology Network Contributions

If you cannot find the required answer, then feel free to ask me.

All the best

Dropping all User Objects Example

This is one in the list of my Example Series in this blog. Check this blog for more possible examples

-- A lot of times I want to drop all user objects in the schema. I use the following script

-- remember to connect first as the user/owner of the objects you want to drop. Do NOT run this as another user or SYS

declare
del_objs integer;
obj_del integer;
cursor get_objs is
select object_type,
'"'||object_name||'"'||decode(object_type,'TABLE' ,' cascade constraints',null) obj_nam
from user_objects
where object_type in ('TABLE',
'VIEW',
'PACKAGE',
'SEQUENCE',
'PROCEDURE',
'FUNCTION',
'SYNONYM', 'MATERIALIZED VIEW')
order by object_type;
cursor get_objs2 is
select object_type, '"'||object_name||'"' obj_nam
from user_objects
where object_type in ('TYPE');
begin
for objrec in get_objs loop
execute immediate ('drop '||objrec.object_type||' ' ||objrec.obj_nam);
end loop;

for objrec in get_objs2 loop
begin
execute immediate ('drop '||objrec.object_type||' ' ||objrec.obj_nam);
exception
when others then
null;
end;
end loop;
end;
/

-- Remember to drop the Queues if you are using AQ
declare
cursor active_queues is select OBJECT_NAME from user_objects where OBJECT_TYPE = 'QUEUE';
cursor active_queue_tables is select OBJECT_NAME from user_objects where OBJECT_TYPE = 'TABLE';
begin
for next_queue in active_queues loop
DBMS_AQADM.STOP_QUEUE (queue_name => next_queue.object_name);
DBMS_AQADM.DROP_QUEUE (queue_name => next_queue.object_name);
end loop;

for next_table in active_queue_tables loop
DBMS_AQADM.DROP_QUEUE_TABLE (queue_table => next_table.object_name, force => TRUE);
end loop;
end;
/

-- Remember to Purge the Recylebin if you are using 10g

purge recyclebin
/

-- Comfirm all is dropped

select * from user_objects
/

Enterprise Manager Upgrade Hints

I have just upgraded my test Grid Control from release 2 (10.2.0.2) to release 3 (10.2.0.3). The first thing did was to read the Readme. This provided most of the hints I need to know and to avoid before I start. For instance, patches to apply and those to rollback.

EM Grid Control Release 3 (10.2.0.3.0) Readme

After that, I picked the release note itself and still went through thoroughly. I know we do not all have the time to do it, but I see it as very cost effective because you spend less time in problem diagnosis after meeting all the requirements.

EM Grid Control Release 3 (10.2.0.3.0) Release Note (Linux and Windows)

I did not have a patch to apply or rollback because the ones mentioned in the release note does not apply to my setup.

I have answered a lot of question relating to upgrades in the Oracle forum and most of the time, they are simply related to pre-install requirements and compatibility. Although the Readme and release notes as rightly pointed out by one of the users, is not always correct, but I see it as the first step before I start looking elsewhere.

Although I had a smaller test system, at the end of it, it went smoothly without a hitch. If I have any problems with it later, then I will look into it as a separate issue because I know the upgrade of both OMS, Agent and repository went OK.

Platform: Windows XP SP2
Dell Latitude D810 Laptop
Intel Pentium M 2.0 GHz Processor
1GB RAM
60GB Hard Drive

Environment: Personal Upgrade Testing for Training purpose.

The same Grid Control installation has gone through various upgrades on my system. Release 10.1.0.3, 10.1.0.4, 10.2.0.2 and now 10.2.0.3. I think I am ready for the next upgrade. What do you think ?

Oracle Database FAQs

Question: I am new to Oracle. What should I do first to get started
Answer: Find and read the Oracle Documentation relevant to your area of interest in Oracle. Oracle Product Documentations are Online at the Oracle website.

See Getting Started: DBA and Oracle Documentation Libraries

Question: Where can I find Oracle Database Documentations?
Answer: The following links will help you

Oracle® 11g Documentation
Oracle® 10g Documentation
Oracle® 9i Documentation
Oracle® 8i Documentation
Oracle® 8 Documentation
Oracle® 7 Documentation

Question: Can I easily install the Software and create the database without using the installation guides
Answer: It is important to read any product's documentation before you start installation. It saves you and your organisation the time you will spend searching the internet and forums for answers to avoidable problems. Most of the Software and Hardware requirements and known issue will be stated in the Installation Guide, ReadMe or Release note.

Questions: Can I skip any of the prerequisite checks?
Answer: You should only skip them whee and when advised by Oracle. The fact that installation completed successfully after skipping some checks does not guarantee that a related problem will not show up later.

Questions: How can I upgrade from Oracle Release A to Oracle Release B
Answer: Every Oracle Release comes with an Upgrade Guide and releated release notes. There is no need for guess work on it. The first thing to do is to pickup up and read the these documents before you start.

Question: When I have two Oracle Homes, which listener should I use
Answer: Use the listener of the later Release.

Question: I have got an error while running a program. What should I do first
Answer: Look at the Oracle Error Messages Manual as the first stop. If you the exaplanation did not help, then search Oracle Metalink and Oracle Forum for similar errors before you post any questions. If searching does not help, then post a question in the correct forum. If you cannot find a solution, then Open Service Request (SR - formerly TAR).

Question: What information do I need to provide when posting a question to Oracle Metalink or Oracle Forum
Answer: State your Product, Version, Release, Platform/Operating System. Mention the latest Patchset and CPU applied. Mention what you did or changed before the error occurred and what you have already done after the error occurred. Ensure you do not write in capital letters as it indicated shouting.

See Oracle Forums Etiquette

Question: Do you have any Hint on Oracle 11g Instalaltion?
Answer: The following links will help you

Oracle® 11g Database Hints


Question: Where can I find Enterprise Manager Documentation?
Answer: The following links will help you

Enterprise Manager Documentation Library

Question: Where can I find Oracle Examples?
Answer: The following links will help you

Oracle® By Example (OBE)

Question: Where can I find Oracle Database Error Messages?
Answer: The following links will help you

Oracle® Database Error Messages

Question: Where can I find information on Duplicating Databases?
Answer: The following links will help you

Creating and Updating Duplicate Databases with RMAN

Question: Where can I find information on Application Server Single Sign On?
Answer: The following links will help you

Configuring Enterprise Manager for Use with OAS Single Sign-On

Question: Where can I find information on Enterprise Security?
Answer: The following links will help you

Configuring Enterprise Manager for Use with Enterprise User Security

Question: Which of the documentations is equvalent to quick guides for DBAs
Answer: In the Documentation Libraries, look fo rthe 2 Day DBA guides. They are simpler to use than the main big guides.

You can use the links at the right pane of this blog to find other topics of interest.

All the best in your Oracle role.

Tackling the Month End Processes

Getting ready for the month End Processes for one of our clients is one of the tasks that keep us busy at this time of the month. Although the tasks involved in the processes have been automated and streamlined, you still have to ensure that things go smoothly.

This Month end processes will started on the 7th and will be completed on the 16th. My part will be 1 day before the d-day and the d-day itself (14th). Other post tasks will be monitoring what other teams are doing.

It is fun as usual, but could be a different story if things go wrong.

Fingers Crossed.

Client and DBA Knowledge Transfer

Will be spending 2 hours in a knowledge transfer session with team members this morning lead by one of the gurus here. This I understand will cover all the services provided for the new client as covered in the service definition with most concentration on the actual Database Adminitration tasks to be provided.

One of the team members just joked "take an anti sleeping tablet with you". Yes, it helps sometimes. You know what I mean.

But I am looking forward to the sessions. Will close in time for lunch though.

Using atomic_refresh Parameter in Oracle Materialzed View Refresh

I was doing a refresh today that involves materialised views from the second schema and a colleague asked me this question. I thought I should share oracle's answer to it.

Why use atomic_refresh=>FALSE?

SQL>execute dbms_mview.refresh('schema.mv_name','C',atomic_refresh=>FALSE);


"Refreshing single MV is not atomic even if ATOMIC_REFRESH = true (the default). This can lead to wrong results in sessions querying against the materialized view as the row count can suddenly change to 0 (as the refresh truncates the MV). An atomic refresh should not affect read consistency in this way"

In 10g a Complete Refresh of single Materialsed View will do a delete instead of truncate. To force the refresh to do a truncate instead of a delete parameter atomic_refresh must be set to false.

That means that since it will be doing truncate instead of delete, the refresh will go faster.

"The dafault value for atomic_refresh in dbms_mview.refresh in 8.1.7, 9i and 10g is TRUE, but in 8i and 9i Oracle does not check the atomic parameter, but because of some enhancements it will do this in 10g"

Just Another Good DBA Day

Just hoping it will be a more interesting day today.

Have just completed my usual morning checks and trying to deal with a support request that have no useful detail on it. Yes, the usual DBA requests that have not got enough information to determine what and where. Sometimes it is like the question in Oracle Forums that you have to ask "What release and Which platform" etc.

This particular request for users to be created without saying where or for which environment. It may not even be within the service deifinition of the projects I support, could be someone else's responsibility or could even be for a different client/account. As usual, I have asked questions and forwarded it to someone who might know for advice.

Well, I am currently working on a Database Shared Service Centre with various clients/accounts to support. This makes the job interesting, but sometimes more demanding.

It's nice a sunny here this morning, but may get rainy later in the day because it is beginning to show some signs of the sun disappearing. Yesterday was good.

Have a good day.

Ask DBMS Direct

I thought I should do something more interesting apart from regular work. Then I said, "Why not start a blog that will help other DBA, Developers and Users".

It has always sounded like an interesting idea. So, here I am.

I will try as much as I can to update this blog. If you find it boring or uninteresting any day do not be sad, visir another day.

Welcome to my blog.