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With SQL server 2014, Microsoft introduced In-Memory OLTP, codename Hekaton. This technology contains revolutionary concepts for optimizing the performance of OLTP workloads via natively compiled stored procedures,memory optimized tables and much more. This session will give you an overview of the different aspects of In-memory OLTP and how this is integrated in the SQL server engine. By giving demo's we will show you what is (im)possible with this new feature and how this really can increase your database performance!
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In Memory OLTP
SQL server 2014 Hekaton Engine
Frederik Bogaerts
Give me more
NSLOOKUP 127.0.0.0
Hekaton in a nutshell
Please ExplainWhy Demo
So long …
Hekaton – In Memory OLTPHash
Indexes
Memory Optimiz
ed Tables
Range Indexe
s
Latch-free
Hekaton Engine
Source: Microsoft.com
Prepare your databaseCreate Database Add memory optimized filegroup Add file to filegroup
Memory Optimized TablesCREATE TABLE [Customer]( [CustomerID] INT NOT NULL
PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT = 1000000),
[Name] NVARCHAR(250) NOT NULL, [CustomerSince] DATETIME NULL
INDEX [ICustomerSince] NONCLUSTERED)WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA);
Limitations No DML
no LOBs, no XML and no CLR data types
No Foreign Key or Check constraints
No UNIQUE indexes other than PK
Max 8 indexes
Data Structures
New Row Format
Versioning : Timestamps
No data page
containers
Row header Payload (table columns)
Begin Ts End Ts StmtId IdxLinkCount
8 bytes 8 bytes 4 bytes 2 + 2 (padding) bytes
8 bytes * (IdxLinkCount)
Source: Microsoft.com
Indexes
Buckets
Point Lookups
HashRange Scanning
BW-Tree
Non Clustered
Hash Indexes
Source: Microsoft.com
Range Indexes
Source: Microsoft.com
Natively Compiled Procs CREATE PROCEDURE [dbo].[InsertOrder] @id INT, @date DATETIME WITH NATIVE_COMPILATION, SCHEMABINDING, EXECUTE AS OWNERAS BEGIN ATOMIC WITH (TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english')
-- insert T-SQL hereEND
LimitationsOnly In MEM tables
No OUTER JOIN, no DISTINCT no OR, no subqueries, no CASE
Limited built-in functions
BUT: Fastest way!
Good news : Interface will be expanded in next version
T-SQL (Not) Supported
INTEROP
Truncate
Dynamic en keyset cursors
Cross database
Linked servers
Locking Hints – Isolation Levels
Merge
Garbage Collection
Multi Versioning Stale Rows Scans slow Bloathing memory
DiagnosticsAll starting with sys.dm_db_xtpDMO
• sys.dm_db_xtp_checkpoint_files• sys.dm_db_xtp_table_memory_stats• Sys.dm_db_xtp_index_stats
XEvents• From SYS.dm_xe_objects O JOIN SYS.dm.xe_packages P on O.package_guid = P.guid where P.name = ‘XtpEngine’
Perfomance Counters• From sys.dm_os_performance_counters where object_name like ‘XTP%’
Keep In MindData in memory at all times
Still using log files
Do not exceed 256 GB of InMem table
Going For Gold
Please ExplainWhy Demo
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A SQL query walks into a bar and sees two tables. He walks up to them and says 'Can I join you?
The SQL query found the table by doing a full scan of the other tables…
In the meanwhile, the waitress arrived at the table. Woohoow what a nice view…
Thank You!
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