Is it possible to view database performance information without DBA privilege in Oracle 11g?

 

The DBA can grant you SELECT privileges to the V$ performance views. It's good for instance tuning, but not as effective as SQL Trace or ADVISOR privilege for query tuning.

How to kill own Oracle SQL sessions without DBA privileges?

 

To successfully run an ALTER SYSTEM command, you don't need to be the DBA, but you do need the ALTER SYSTEM privilege to be granted to you (or to the "user" owning the application through which you connect to the database - which may be different from "you" as the "user" ).

Postgres Frequently used commands - CHEAT SHEET

 \db- List all tablespaces

\dn- List all schemas

Postgresql Database Starts with 100% CPU processes ?

If you have a problem with PostgreSQL, it starts some processes that consume lots of resources. You kill those processes but they will restart after a few minutes.

Later you check the /var/log but there is nothing about this. What does that mean?😟

Oracle : Move indexes to another tablespace

 

Postgres High Availability Terms

 What is High Availability?

It is the amount of time that a service is available and is usually defined by the business.

Oracle Session Kill Script - Session Management

 

Possible ways to recover space from deleted rows with insufficient disk space remaining for full vacuum

 A recent scenario,

We had a single table with about 50M records that use around 80gb of space. Application recently deleted older records which was no longer needed reducing the Number of records to 30M.

What to do if listener log has grown too big in size

 

RMAN Backup Validate

 Sometimes RMAN backup files might get corrupted. Sometimes disk block corruption might happen. So it is better we do validate the database backups more frequently in order to make sure it is recoverable.

Oracle Blocksize selection

I had gone through Oracle documents, forums, and other websites but could not get a clear picture of what blocksize to choose for my environment where 64 bit OLTP databases are running. I came across the following websites that give practical and more useful information about Oracle Block size selection.

http://www.ixora.com.au/tips/buffered_block_size.htm

http://www.nextre.it/oracledocs/blocksize.html

The Surprising Impact of Medium-Size Texts on PostgreSQL Performance

 This is a great explanation of Postgres toast internals for anyone who doesn't know about them 

https://hakibenita.com/sql-medium-text-performance

PostgreSQL : Influencing Query Execution Plan

By enabling and disabling the following parameters, we can influence the query execution plan generated by the optimizer.

MySQL : Troubleshooting Replication

If you have followed the instructions to make a replica (If not have a visit at this quick post), and your replication setup is not working, than the first thing to do is check MySQL error log. (if you dont know where it is? Just check my.cnf for the location of that file). Most of time, you will get the actual error from the log if not than you can try below things.

 

• Check master server and verify that binlog is enable or not and position is rotating or not by using “show master status” command.

• Master and slave server both must have unique server_id.

• Run “show slave status” command on slave server and check below values first.Slave_IO_Running:Slave_SQL_Running: Last_errno: 0 Last_error:

• If “Slave_IO_Running” is “YES” than slave is able to connect master and getting log entries from master but if it’s “NO” that means slave is not able to connect to master so check the values of Master_Host, Master_User, Master_Pass that it is right or not. Also check the connectivity between master and slave for mysql as well as network side.

• If “Slave_SQL_Running” is “YES” than no issue with sql thread butit its “NO” than you should get error on “Last_error”.

• Most of time, you will get the query related error in “Last_error” section.

• If the slave was running previously but stopped suddenly than the reason usually is that some statement that succeeded on the master failed on the slave.

• If a statement that succeeded on the master but refuses to run on the slave, try to do the below things. Because it‘s not feasible to do a full database resynchronization from the masterby copying a new snapshot/backup from the master.

• Sometimes, its happening when table changes are done in master server but somehow its not replicated on slave so slave will refuse to run the statement and give error. In this situation, we have synchronize the changes and start replication with simple “Start Slave” command.

• Sometimes, we are getting some error which can be solve by running that statement manually. At that time we can just stop slave completely, skip the statement with “ set global sql_slave_skip_counter=1” command, start the slave.

ORA-00845: MEMORY_TARGET not supported on this system

Recently, when I tried to increase the memory_target of Oracle database, I got the following error:

ORA-00845: MEMORY_TARGET not supported on this system

While checking, we found that /dev/shm size was 2 GB, but we were trying to increase the memory_target values to 7 GB that is more than the size of /dev/shm.  So we got the error.

Then we increased the /dev/shm size to 8 GB using the command as below

 mount -t tmpfs shmfs -o size=8192m /dev/shm

After that, we were able to bring up the database with the parameter value memory_target =7G without the issue.

Create Extension Fails : ERROR: could not access file "$libdir/dblink"

 

After my recent DB upgrade activity, I was unable to create extension and was failing with the below errors.

Find Uptime in PostgreSQL

 There are various ways to know since how long PostgreSQL is running. 

Below will cover 3 ways to find this.

PostgreSQL Set DB Timezone

If you plan to work with date and time data in PostgreSQL, you’ll want to ensure that you’ve set the correct time zone for your location. Fortunately, it’s easy to make this change using the psql command-line interface. In this article, we’ll explain how to connect to PostgreSQL and set the time zone.

Mysql Database Installation and Administration

MySQL is an excellent open-source relational database management system. In 2010, MySQL was forked into MariaDB after its purchase by Oracle. MariaDb is a community driven and developed, relational database management system (RDBMS). It continues to be a free and open-source software licensed under the GNU General Public License.

Clear RAM cache, buffer and swap space in Linux

 

Clean up the page-cache :

   # sync; echo 1> / proc / sys / vm / drop_caches

  

Clean dentrie and inode caches:

     # sync; echo 2> / proc / sys / vm / drop_caches

 

To clean the page-cache, dentrie and inode caches:

     # sync; echo 3> / proc / sys / vm / drop_caches

 

# swapoff -a && swapon -a

 

1) Shutdown the database and its services (pg_ctl stop , sudo service postgresql stop, etc.)

2) sync

3) sudo echo 3> / proc / sys / vm / drop_caches

4) Start the database server

 

free && sync && echo 3> / proc / sys / vm / drop_caches && free

Found this post interesting? Subscribe us  😊😉

Read more 

Configure Streaming Replication in PostgreSQL

All about Physical Replication and Log shipping in Postgres 

Streaming-Replication Sync and Async, benefits of streaming replication over Log-shipping

Oracle Account Issue

 Sometimes the database user account is getting locked if the login was tried with the wrong password. In 11g database, the user account will get locked after 10 consequent failed login attempts. Oracle 11g database's default profile makes the database account password lifetime as 3 months and the number of failed login attempts as 10 days.  Once these limits are reached, it will lock the account.

The following command can be used to change the default profile to allow an unlimited number of failed login attempt:

alter profile default limit FAILED_LOGIN_ATTEMPTS unlimited;

The following command can be used to change the default profile to allow an unlimited number of days as password lifetime.

ALTER PROFILE DEFAULT LIMIT PASSWORD_LIFE_TIME UNLIMITED;

MySQL : Cache

 

Following caches are generally available in MySQL.

 

Streaming replication - Sync and Async, benefits of streaming replication over Log-shipping in Postgres

In my previous post here, I tried to explain how the log shipping works and its advantages. Let's see more about Streaming replication in Postgres.

Read-only user in PostgreSQL

 

As a Database Administrator, we always classify various types of schema with specific privileges. In the standard application, there are a few various types of Database Users like Application user, Read-only user, Admin user.

PostgreSQL Ora2Pg : Migrate Oracle to Postgres

Ora2Pg is Free Software written and maintained by Gilles Darold. Its an Ideal for large migration projects.

 

3 Reasons to move to PostgreSQL :

• Reduce Infra & Business Costs
• Reduction of license costs to ZERO
• Reduction of support costs by 80% or more