2/18/2017

Performance information that we have to take from users

Performance information that users can provide

We can notice the system tuning is required when first we get a complaint from the users. 

Performance_Tuning_DB2


When we do not have enough time to change the performance tuning objectives, we can know the performance statistics by asking few questions to the users who complains us about the performance degrade.

we can usually determine where to start looking for a problem by asking a few simple questions.
Those are..

1/27/2017

How Will Logging Process happen in DB2?

What is a Log:

Log is nothing but a transaction log. A transaction log is a file which stores the history of actions executed by a database management system, which is used to recover at the time of crashes.

All databases maintain log files that keep records of database changes.

Types of logging strategy choices:

1. Circular logging
2. Retain log records

9/27/2016

How to resolve this Query Optimization issue?

Query Optimization Issue:

Assume that a query is executing by a application developer or a client. The query has all the indexes on the columns which are required and performed well upto certain time, suddenly got complaints about the same query that it is not performing well taking too much time to retrieve. Please leave your valuable comments how you people can resolve this issue.

9/25/2016

Difference between Online Reorg and Offline Reorg in DB2

Online reorg vs Offline reorg:

Offline or Classical Reorg:

So many people think that Offline reorg quiesces the database, so no applications are able to connect or access the tables. But while performing offline reorg applications can access tables, but they have limited access. Read access only at the time of SORT and BUILD phases.

9/22/2016

What are the different phases of Online & Offline Reorg in DB2 ?

Different Phases of Reorg:

Basically Reorg sorts the data using index scan or table scan and moves the records from one page to a previous page which has some free space due to deletion of rows from a table to reclaim the space.

There are "TWO" types of reorgs:
  • ==> Offline reorg or Classic reorg
  • ==> Online reorg or Inplace reorg
Each reorg type consists of different phases of execution.

9/08/2016

What are the DB2 LUW DBA daily activities?

DB2 DBA Daily Activities:

Daily Activities:

  • ==> Verify all the instances and databases are running.
  • ==> Check the backup status of the databases.
  • ==> Check the archiving of database logs.
  • ==> Verify the pruning of database backups and archival logs.
  • ==> Check the status of Reorg/Runstats jobs if you have enabled.
  • ==> Check the db2 diagnostic logs and notification logs.
  • ==> Check the size/status of each mount database server is using.

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