SQL Server In-Memory Internals and Performance Tips

SQL SERVER IN-MEMORY INTERNALS

By Hamid J. FardMicrosoft Certified Master: SQL Server 2008

Microsoft Certified Solutions Master: Charter-Data PlatformCIW Database Design Specialist

Copyrights © 2016 Fard Solutions Sdn Bhd, All rights reserved.

Agenda• What is In-Memory OLTP?• In-Memory OLTP Components.• Memory-Optimized Table Requirements.• Memory Optimized Tables.• Memory Optimized Indexes.• In-Memory Query Processing.• In-Memory Transactions.• In-Memory Memory Estimation.• In-Memory Filegroup Configuration.• In-Memory Data and Delta File Population.


What is In-Memory OLTP?


In-Memory Table

Disk Based Table

Benefits:• Eliminate contention.• Reduce logging.• Lower latency data retrieval.• Minimize code execution time.• Efficient data retrieval.• Optional IO reduction or removal,

when using non-durable tablesImplementation Scenarios:• High data insertion rate from

multiple concurrent connections.• Read performance and scale with

periodic batch inserts and updates.• Intensive business logic processing

in the database server.• Low latency.• Session state management.

In-Memory OLTP Components


In-MemoryPerformance

Memory-Optimized Table Requirements.


Hardware Software

• X64 Architecture Processor• <60 Processor Cores• Enough Memory (x2 Table Size)• Enough Storage (x2 Table Size)• Processor Needs to Support

cmpxchg16b

• X64 Architecture Edition• Enterprise or Developer Edition• Hyper-V to Support cmpxchg16b (If

needed)• Enable Instant File Initialization

Memory Optimized Tables.

SQL Server CLR In-Memory Table


Memory Optimized Indexes.


Made for point lookups Made for range scans and ordered scans

In-Memory Query Processing


Disk Based Query Plan SQL Server Query Processing for Disk-Based Tables

INTerpreted Transact-SQL Access to Memory-Optimized TablesMemory Optimized Query Plan

In-Memory Query Processing (Cont.)


Native compilation of stored procedures

Execution of natively compiled stored procedures

In-Memory Transactions


Lifetime of a transaction that accesses memory-optimized tables

Regular Processing Validation Phase Commit Processing

• Commit Dependency• Repeatable Read Validation• Serialization Validation

In-Memory Memory EstimationCREATE TABLE IMOLTP (col1 INT NOT NULL PRIMARY KEY NONCLUSTERED,col2 INT NOT NULL INDEX INDEX_1 HASH WITH (BUCKET_COUNT = 5000000),col3 INT NOT NULL INDEX INDEX_2 HASH WITH (BUCKET_COUNT = 5000000),col4 INT NOT NULL INDEX INDEX_3 HASH WITH (BUCKET_COUNT = 5000000),col5 INT NOT NULL INDEX INDEX_4 NONCLUSTERED,col6 CHAR (50) NOT NULL, col7 CHAR (50) NOT NULL, col8 CHAR (30) NOT NULL, col9 CHAR (50) NOT NULL)WITH (MEMORY_OPTIMIZED = ON)

Memory for Table: Timestamps + Index Pointers + Row Data => 24 + (8+8+8+8) + (4+4+4+4+4+50+50+30+50) => 256 x 5000000 => 1.28GBMemory for Hash Indexes: Round Up Bucket Count x Index Pointer => 223 x 8 => 67,108,864 Bytes => 64MB x 3 => 192MBMemory for Non-Clustered Index: (Index Pointer + SUM(Key Column Data Type Size)) x Unique Rows => (8 + 4) x 5000000 => 57MB Memory for Row Versioning: (Longest Trans. Duration in Sec. x Peak No. of Row Updates & Deletes in Sec.) x Row Size

=> ( 1 x 10) x 256 => 2560 Bytes => 2560 x (0.3 x 5000000) => 3.66GB


In-Memory Filegroup Configuration


In-Memory Data & Delta File Population


Questions and Answers
