Hekaton is Microsoft SQL Server's in-memory OLTP engine. It allows for creating memory-optimized tables to fully leverage RAM and provide faster performance than disk-based tables. Memory-optimized tables use new row formats and indexing structures like hash and range indexes that are optimized for memory. Stored procedures can be natively compiled for maximum speed when operating on memory-optimized tables. There are some limitations around data types and features supported. Diagnostic objects like DMVs provide visibility into Hekaton's memory usage and performance.

1. In Memory OLTP
SQL server 2014 Hekaton Engine
Frederik Bogaerts

2. Give me more

3. NSLOOKUP 127.0.0.0

4. Hekaton in a nutshell
Please
Explain
Why Demo

5. So long …

6. Hekaton – In Memory OLTP

7. Hekaton Engine
Source: Microsoft.com

8. Prepare your database
Create Database
Add memory optimized filegroup
Add file to filegroup

9. Memory Optimized Tables
CREATE 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);

10. 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

11. 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

12. Indexes
Buckets
Point
Lookups
Hash
Range
Scanning
BW-Tree
Non
Clustered

13. Hash Indexes
Source: Microsoft.com

14. Range Indexes
Source: Microsoft.com

15. Natively Compiled Procs
CREATE PROCEDURE [dbo].[InsertOrder] @id INT, @date DATETIME
WITH
NATIVE_COMPILATION,
SCHEMABINDING,
EXECUTE AS OWNER
AS
BEGIN ATOMIC
WITH
(TRANSACTION
ISOLATION LEVEL = SNAPSHOT,
LANGUAGE = N'us_english')
-- insert T-SQL here
END

16. Limitations
Only 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

17. T-SQL (Not) Supported
INTEROP
Truncate
Dynamic en
keyset
cursors
Cross
database
Linked
servers
Locking
Hints –
Isolation
Levels
Merge

18. Garbage Collection
Multi
Versioning
Stale
Rows
Scans
slow
Bloathing
memory

19. Diagnostics
All 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%’

20. Keep In Mind
Data in memory at all times
Still using log files
Do not exceed 256 GB of InMem table

21. Going For Gold

22. Please
Explain
Why Demo

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25. 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…

26. Thank You!

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