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SQL SERVER INTERNALS & ARCHITECTURE
Kevin Kline, SQL SentryDirector of Engineering Services, [email protected] SQL Server MVP since 2003Twitter , Facebook, LinkedIn @ KEKlineWebsite: http://KevinEKline.com/, http://ForITPros.com
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DROPPING ACID - WHY DOES SQL SERVER DO WHAT IT DOES?
• ACID properties of Transactionso Atomico Consism tento Isolatedo Durable
• Speed, scalability, and
performance; Maximize hardware• Competitive features
OUR TOUR GUIDE
Talk nerdy to me, baby!
OK, WE’RE DONE
Relational EngineOptimizer
Query Executor
Cmd Parser
Storage EngineTrans-action Manager
Buffer Manager
Access Methods
Protocol LayerSNI
Data File
T-Log
Buffer Pool- - - - - - - - - - - -Data Cache
- - - - - - - - - - - - Plan Cache
SQL Server Network Interface
TDS
LanguageEvent
SELECT
?
QueryTree
QueryPlan
OLEDB
?
SQLOS AND SCHEDULERS • 1 Cash Register = 1 Scheduler• Users are assigned
to a thread
Uh oh! The out of soda!
No problem. Step aside… More syrup for the sodas!
Goes to the waiting, i.e.“suspended queue”
Yeah! I’m next in line!
Relational EngineOptimizer
Query Executor
Cmd Parser
Storage EngineTrans-action Manager: Log & Lock Mgr
Buffer Manager
Access Methods
Protocol LayerSNI
Data File(s)
T-Log
Buffer Pool- - - - - - - - - - - -Data Cache
- - - - - - - - - - - - Plan Cache
SQL Server Network Interface
TDS
LanguageEvent
SQLOS
?
QueryTree
QueryPlan
OLEDB
DataWrite ?
Check Point
Lazywriter
Latches
Locks
TROUBLE-SHOOTING WAIT
STATS?Async_Network_IO
SOS_Scheduler_Yield
Pagelatch_x, Latch_x, Resource_Semaphore
LCK_x, LCK_M_x
Writelog, Logbuffer
PageIOLatch_x, Async_IO_Completion,
IO_Completion
CACHES?
• How long does a page of data or a block of code stay in cache?
• Uses a LRU algorithm• Usually performed by the lazy-
writer, but can also be done by any worker thread after scheduling its own I/O
CACHE AGING & LRU-K BEHAVIOR
getord
Memory
finduser
sp_1 sp_4
16 16
7
2233 02
7
1
564
01
14151312
What about buffer cache?
BUT WAIT! THERE’S MORE!
Relational EngineOptimizer
Query Executor
Cmd Parser
Storage EngineTransaction Manager: Log & Lock Mgr
Buffer Manager
Access Methods
Protocol LayerSNI
Data File
T-Log
Buffer Pool- - - - - - - - - - - -Data Cache
- - - - - - - - - - - - Plan Cache
SQL Server Network Interface
TDS
LanguageEvent
INSERT, UPDATE, orDELETE
?
QueryTree
QueryPlan
OLEDB
DataWrite ?
Oooh! So dirty!
CheckPoint
Lazywriter
Relational EngineOptimizer
Query Executor
Cmd Parser
Storage EngineTrans-action Manager: Log & Lock Mgr
Buffer Manager
Access Methods
Protocol LayerSNI
Data File(s)
T-Log
Buffer Pool- - - - - - - - - - - -Data Cache
- - - - - - - - - - - - Plan Cache
SQL Server Network Interface
TDS
LanguageEvent
SQLOS
?
QueryTree
QueryPlan
OLEDB
DataWrite ?
Check Point
Lazywriter
Latches
Locks
HEKATON, A.K.A. IN-MEMORY OLTP
SUMMARYUnderstanding the internals is as
important as any other bit of info
you might haveRemember:ACID!!!key components of the relational engine?key components of the storage
engine?Key areas of cache?Key areas of the transaction
manager?What two processes conduct
writes?More info?
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