managing sqlserver
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Managing SQL Server (for Admins WhoManaging SQL Server (for Admins Who’’d d Really Rather Not)Really Rather Not)Don JonesDon JonesSenior Partner & Principal TechnologistConcentrated Technology, LLC
This slide deck was used in one of our many conference presentations. We hope you enjoy it, and invite you to use it
within your own organization however you like.
For more information on our company, including information on private classes and upcoming conference appearances, please
visit our Web site, www.ConcentratedTech.com.
For links to newly-posted decks, follow us on Twitter:@concentrateddon or @concentratdgreg
This work is copyright ©Concentrated Technology, LLC
IntroductionsIntroductions
Me: Don Jones, Concentrated Technology– Microsoft MVP Award recipient– Contributing Editor, TechNet Magazine– Author of 45+ IT books– Blogger at http://ConcentratedTech.com
You: The “Microsoft Person” in your environment– Not primarily concerned with supporting
Microsoft SQL Server…– …but more or less forced to do so anyway
AgendaAgenda
Peeking Under the Hood: How SQL Server Works
Backup and Restore Operations About the Query Optimizer Index Maintenance and Tuning Key Database Configuration Options SQL Server Security Model Key Server Configuration Options High Availability and Replication
Options
How SQL Server Works, Part 1How SQL Server Works, Part 1
SQL Server stores data in 8KB chunks called “pages”
It always deals with data in these 8KB chunks
Generally speaking, all data for a single table row must fit onto a single page– It’s actually possible for certain types of data to
spread across multiple pages– Sometimes, the page can contain a pointer to a
file on disk – the FILESTREAM data type
The pages live in one or more files (.MDF, .NDF) on disk, but are always read or written in 8KB units
How SQL Server Works, Part 2How SQL Server Works, Part 2
When a query is issued that results in data being changed, added, or deleted:1. SQL Server makes a note of the query in its
transaction log
2. The database engine determines what page(s) are affected by the change
3. The affected pages are loaded into server memory
4. The changes are made in memory
• At this stage, the changes have been completed only in RAM.
• If something else reads those pages, they’re already handy in memory.
How SQL Server Works, Part 3How SQL Server Works, Part 3
Eventually, the modified pages are written to disk.
When this happens, SQL Server “checks off” the associated query in the transaction log.
In the event of a sudden failure:– When SQL Server restarts, it looks to see
if any “un-checked” queries are in the log.– If so, it “re-plays” those queries to bring
the database up to speed.
If you have the transaction log, you can recover the data!
SQL Server BackupsSQL Server Backups
Three types:– Full – Backs up the entire database and
removes (“truncates”) all “checked” entries from the transaction log
– Differential: Only what’s changed since the last Full; also truncates the log
– Transaction log: Only grabs the current transaction log; truncates the active log afterward
Restoring a DatabaseRestoring a Database
1. Start with the most recent Full backup• Leave the database in “restore mode” if you
have other files
2. Apply the most recent differential• Stay in “restore mode” if you have more files
3. Apply any transaction logs since the differential was made• When finished, allow recovery to begin
• Maximum amount of data at-risk: Any changes made since the most recent transaction log backup
• Moral: Frequent T-Log backups!
IndexesIndexes
Two types:– Clustered
Every table has one, even if it’s just on the row ID number.
Governs the order in which data is logically stored
Should be on whatever column is used most for lookups or table joins
– Non-ClusteredEvery table can have zero or moreActs as a literal index, keeping
entries in order by the indexed column and pointing to the full data row
A “covering” index is one that contains entries for every column being queried
Indexes: Pros and ConsIndexes: Pros and Cons
Pros– Indexes can speed up the time it takes to find
data
– Also speed up sort times
– Ideally, index on all columns that are frequently used in a WHERE or ORDER BY clause
Cons– Indexes slow down data add/change/delete
operations, because indexes must also be updated
– Ideally, index nothing
The reality is a balancing act: Building indexes on columns that deliver the most benefit, with the least downside
Index Problem: FragmentationIndex Problem: Fragmentation
Occurs when index pages become full and data needs to be inserted into the middle
A “page split” occurs to make room for the new entry, causing the pages to be “out of order” – this decreases performanceAndrew
AndrewsBatistaBarbaraCharlesCharlie
FrankGary
GrossmanHughInaJack
JacksonJones
Kimberly
DonavanEricErin
NEW!NEW!
Fixing FragementationFixing Fragementation
Reorganizing or Rebuilding the index will put the entries and pages back into the correct order, improving performance
You can specify a “fill factor” that leaves empty space for new entries without splitting pages as often
However, emptier pages mean SQL Server has to work harder to read the same amount of data – so this is a balancing act
RulesRules
Fragmentation 30%+ = Rebuild– Rebuild with ONLINE option in 2005+ to
avoid locking table(s) (unless it has BLOBs)– Recomputes statistics– Takes more overhead– Needs free disk space
Fragmentation 10%-30% = Reorg– Requires less overhead (just swaps pages)– Always “online”– Less effective
14 • Don Jones • ConcentratedTech.com
Index TuningIndex Tuning
The indexes that made sense for a database on day 1 might not make sense after it has been in use for some time
You can use SQL Profiler to capture real-world, representative query traffic…
…and feed that to the Database Engine Tuning Advisor to get recommendations on index improvements
The Advisor can even help you implement those changes that you decide to proceed with
Key Database Options and Best Key Database Options and Best PracticesPractices Allow statistics to Auto-Create/Update
– This makes sure the Query Optimizer knows which indexes exist and what kind of condition they are in
Consider disabling auto-growth, or at least monitor it– Auto-Grow can consume time; better to
manually size the database files appropriately Disable Auto Close except on infrequently-used
databases– Closed databases incur a performance hit
when someone queries them since SQL Server has to open the file
SQL Server Security ModelSQL Server Security Model
Login: Map to a Windows user/group, or an in-server credential; gets you access to the server
Server Role: Contains logins, and defines server-wide privileges
Database user: Maps to a login, and gets you into a database
Database Role: Contains database users, and defines in-database privileges
Custom Database Role: Same as the built-in ones, but you define the permissions
App Role: Shortcut login+database user+permissions designed to be activated by an application that defines its own security layer for the data.
Server OptionsServer Options
Authentication Mode: “Windows” or “Windows+SQL Server”
Memory and Processor options (typically, leave alone)
Instances– Each “instance” is an independent installation of
SQL Server
– Has its own “server-wide” options (“instance-wide” is a better term)
– Default instance: Connect using server name
– Other instances: Connect using SERVER\INSTANCE format
– Review list of services to see instances – each instance has its own SQL Server service
High Availability OptionsHigh Availability Options
Log Shipping Database Mirroring Windows Clustering
Replication OptionsReplication Options
Snapshot Transactional Transactional with Updating
Subscribers Merge
Off-Topic: Microsoft Sync Framework / Sync Services for ADO.NET
Final ThoughtsFinal Thoughts
SQL Server Agent (and Jobs, Operators, and Alerts)
Multi-Server Admininstration
ConclusionConclusion
A few basic admin skills can help you perform the most often-needed SQL Server tasks
Keep in mind that the SQL Server Management Studio can connect to multiple servers for single-seat administration
Final Notes…Final Notes…
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Thank you very much!
23 • Don Jones • ConcentratedTech.com
This slide deck was used in one of our many conference presentations. We hope you enjoy it, and invite you to use it
within your own organization however you like.
For more information on our company, including information on private classes and upcoming conference appearances, please
visit our Web site, www.ConcentratedTech.com.
For links to newly-posted decks, follow us on Twitter:@concentrateddon or @concentratdgreg
This work is copyright ©Concentrated Technology, LLC