Re: Are these too harsh ?

From: Michael Lackey <mlackey_at_illuminet.com>
Date: Sat, 21 Jul 2001 21:25:17 GMT
Message-ID: <600e9c26.0107031341.7eba4989@posting.google.com>

I would tend to organize my questions into categories to get a better picture of where the potential DBA's strengths and experiences are. For example if they are only weak in the development area but are very strong in
DBA fundamentals, that means more to me than an overall score of 60%.

How specific your questions get and on which features really depends on your specific DBA requirements at your site. Your standby database question for example,
some organizations may never have a need for that.

Here is a quick stream of thoughts:

For each category I would ask what their responsabilties were at their last/current DBA job.

OS experience

	How well do they know the OS oracle will run on at your site?
	Do they have Admin experience on this platform?
	Can they write scripts to manage the database in this OS?
	
Installation
	How many have they done and what size and platforms?
	What products/versions have they installed?
	Use Oracle Flexible Architecture (OFA)?
	Upgrades they have performed?
	

Database Design/Architecture

	tablespace storage settings?
	partitioning?
	How involved in the design process have they been in previous
database applications?
	VLDB Experience?
	Analysis skills?
	Analaysis and design toolsets used?
	Object Orientation?
	Work with LOBs?
	

Oracle Instance Architecture  

	SGA Questions . . .
	SMON/PMON/DBWn questions . . .
	rollback segments (how many and why)?
	redo logs/group
	controlfiles and multiplexing
	

Instance Documentation

	What do you document?
	What about disaster recovery documentation?
	

Oracle Instance Configuration Issues

        db_block_buffers/shared_pool_size/db_block_size etc.

Oracle Instance Monitoring/Maintenance         

	current tablespace capacity and wasted space
	tablespace extents
	on/offline tablespaces or datafiles
	redo logs
	rollback segments 
	
	

Performance Monitoring

	How do you do this?
	have you written scripts/programs to do this?
	Used any software to do this (OEM)?
	Top sessions and resource hogs?
	Resource limiting and management?
	coalescing tablespaces
	Table statistics
	chained rows

Security

        Every use anything other than users/roles/profiles such as external security like kerberos (sp?)?

Developent

	PL/SQL experience?
	Provide Support to developers?
	Work with Oracle Objects Module?
	XML/JAVA?
	snapshots
	packages
	sequences
	synonyms
	Change management

Backup/Recovery and Corruption

	experience with cold/hot/RMAN backups and recovery?
	Why not just use RMAN?
	read-only Tablespaces
	interfacing with Tape management?
	archive logging
	exports
	moving a database
	Disaster Recovery Experiences
		worst nightmare
		worst real life experience
		Performed complete proof of concept on recovery scenarios?

High Availability

	Standby database
	OPS
	Clustering software like Veritas?

Personality
	Anxiety Disorders and Medication :)
	Sleep Deprivation survival techniques :(
	Team/Enterprise Player?
	Can you sleep with a pager under your pillow?

Oracle Tools
	OEM
	RMAN
	SQLPLUS
	etc.

A few humble opinions on your specific questions:

• What are the various shutdown modes for the database?
• List the steps that Oracle goes through at database startup

        If they flench, send them packing.

• Describe the basic mechanics of how hot backup works?
• Besides the overhead of copying the files to disk/tape, what other performance issues are relevant during a hot backup, namely, why do many sites try to keep the time spent in backup mode to a minimum?

        My question to you is why not use RMAN?

• What is the difference between a latch and a lock? Give an example of use of each
• What is "spinning" as it pertains to a latch?
• What is the Oracle log buffer? Describe how Oracle uses latches as information is written into the log buffer

        I never focus much on this myself unless you had problems in these areas.

• What are the positives and negatives of a large database block size on indexes?
• What does the "explain plan" command do
• How would you determine the amount of I/O occurring on each datafile in the database ? If a great deal of this is occurring on the TEMP tablespace what is the likely cause ?
• Describe how you would determine whether an index requires rebuilding ?

        Great questions.

• On a Unix machine, you see an oracle process using all of the CPU. Assuming it is due to a poorly written SQL, describe how to determine the SQL that is causing the problem, starting with the Unix process ID.

        Valid question to ask. Don't let them miss this one.

• List the pros and cons of using bind variables
• What are the advantages of creating code using packages over standalone PL/SQL procedures

        While I am a personal fan of using these, not really a DBA issue but more of

        a development and standards issue. Great topics for conversation though.

• Describe the common RAID levels used for Oracle databases and how they typically pertain to performance

	Could be a little technical for some and a decision we typically make
	as a group depending on speed requirements verses up-time verses

cost.

• Describe how and why a PL/SQL module could be defined as an autonomous transaction
• Your database contains a view, which joins two tables. It is possible to insert, update, and delete rows from this view. - Describe two ways of implementing this.

        Seem more developer than DBA oriented to me.

mickrice_at_techie.com (Mick Rice) wrote in message news:<645b6e08.0106260100.7374431f_at_posting.google.com>...

> Conor,
>       Many of the questions seem fine to me while others appear fairly
> obscure. I'd be of the opinion that if anyone comes up with
> 'reasonable' answers to all or nearly all of these questions then
> you're probably dealing with someone who's not going to be
> particularly happy in the role you describe. In other words they'll be
> more towards the genius end of the scale rather than the George W.
> Bush end :-) I'd question, as others seem to also, whether you
> actually need someone with all of this stuff already in their head as
> opposed to someone with a lot of it and a willingness/ability to get
> the rest,
> 
> Mick Rice.

Received on Sat Jul 21 2001 - 16:25:17 CDT