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Basic Operations on MySQL Users

 Atikh Shaikh     mysql     No comments   

In this article we are going to discuss about different operations on mysql user like lock, unlock, grant, revoke etc.

  • Lock-unlock
  • Expire-unexpired
  • Check privileges
  • Revoke privileges
  • Change password
  • Rename user (single user, multiple user)
  • Drop user
User list can be fetched using query mentioned below in the database

select user,host,authentication_string,password_expired,account_locked from user where user like 'test%';

We can all accounts are unlocked and password not expired. We will perform operations one by one


LOCK and UNLOCK

Let’s lock and unlock test@%
Locking the account
    alter user ‘test’@’%’ account lock;
Checking the status
    select user,host,authentication_string,password_expired,account_locked from user where user like 'test%';

Unlocking it again
    alter user ‘test’@’%’ account unlock;

This will affect only test@% not test@localhost, both are different users.


EXPIRE

Let’s expire password for 'test'@'localhost' and revert it
alter user ‘test’@’localhost’ password expire;

Verification
    select user,host,authentication_string,password_expired,account_locked from user where user like 'test%';

Password reset using values
    alter user ‘test’@’localhost’ identified with ‘mysq_native_password’ as   ‘*5BA7FD292EB16719F76792ECAF589CE4B62CCC94’;


Verifying status again
    select user,host,authentication_string,password_expired,account_locked from user where user like 'test%';


CHECK PRIVILEGES
show grants for ‘test2’@’locahost’;


REVOKE PRIVILEGES
In below example grants of test2@localhost has been revoked
show grants for ‘test2’@’localhost’;
revoke SELECT, INSERT, DELETE CREATE, DROP, RELOAD, ALETER ON *.* from ‘test2’@’localhost’;
flush privileges;
show grants for ‘test2’@’localhost’;



CHANGING PASSWORD
In below example password of test3@% has been altered.
select user, host, authentication_string, password_expired, account_locked from user where user like 'test%';
alter user ‘test3’@’%’ identified by ‘Hudrt#12’;
select user, host, authentication_string, password_expired, account_locked from user where user like 'test%';



RENAME USER
show grants for ‘test1’@’localhost’;

Single user 

In mysql we can rename the user without dropping it but modification needs to be carried wherever it is not getting used, grants will not get altered

Single user- in below example ‘test1’@’localhost’ user has been renamed with ‘xyz1’@’localhost’

rename user ‘test1’@’localhost’ to ‘xyz1’@’localhost’;
show grants for ‘xyz1’@’localhost’;
select user, host, authentication_string, password_expired, account_locked from user where user like xyz1%';


Multiple user
select user, host, authentication_string, password_expired, account_locked from user where user like 'test%';
rename user ‘test’@’localhost’ to ‘abc’@’%’,
            ‘test’@’%’ to ‘abc’@’localhost’;
select user, host, authentication_string, password_expired, account_locked from user where user like 'test%';
select user, host, authentication_string, password_expired, account_locked from user where user like 'abc%';



DROP USER
In below example we are dropped abc user
select user,host from user where user=’abc’;
drop user ‘abc’@’localhost’;
select user,host from user where user=’abc’;
drop user  ‘abc’@’%’;
select user,host from user where user=’abc’;

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Oracle : STATISTICS_LEVEL parameter

 Atikh Shaikh     oracle, Performance     No comments   

In Oracle as we gather and view statistics though different views or tables can be controlled by instance level parameter STATISTICS_LEVEL
This particular parameter has below three possible settings

  • BASIC
  • TYPICAL
  • ALL
The parameter controls automatic gathering of statistics at two levels 
Instance statistics : statistics accumulate withing instance regarding activity
Object statistics : stats accumulated on objects within database

The instance statistics accumulated in memory and flushed to AWR ( automatic workload repository) by MMON (manageability monitor) background process
Object statistics are gathered by DMBS_STATS procedure calls

Now we will discuss about parameter setting 

TYPICAL : The default setting is TYPICAL, this setting will gather all statistics needed by self management and tuning capabilities of the database and will also enable automatic object analysis task that runs daily in maintenance window

BASIC: The BASIC setting disable  AWR statistics and disable daily analysis
ALL : ALL setting gathers all possible statistics, these include operating system statistics and very detailed statistics on SQL statement execution. This shortcoming with this method is it will impact performance adversely.

Suggestion : this parameter should always be kept default and of ALL setting is required should be kept for short term.

This parameter can be altered runtime using simple alter system command

alter system set STATISTICS_LEVEL= BASIC;
alter system set STATISTICS_LEVEL= TYPICAL;
alter system set STATISTICS_LEVEL= ALL;

and same can be viewed using

show parameter  STATISTICS_LEVEL

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