Ling to SQL and Entity Framework performance analysis

Linq to SQL and Entity Framework performance comparison and optimization Alexander Konduforov Email: alexander.konduforov@gmail.com Weblog: www.merle-amber.blogspot.com

Goals
explain the L2S and EF architectures
give an understanding of performance losses and bottlenecks
describe the possible ways of performance improvements
check the real benefits of the performance improvements
analyze the results, give advices

General ORM architecture Objects provider Query Records Data Objects SQL Database provider Databases Databases Databases Query Mapping

Linq to SQL architecture Linq to SQL Data Context LINQ Records Data IEnumerable<T> SQL SQL LINQ Linq to SQL Data Provider MS SQL Server SQL

Entity Framework architecture ADO.NET Data Providert ADO.NET Data Provider ADO.NET Data Provider Object Services LINQ to Entities CCT xDataReader DBDataReader IEnumerable<T> ESQL CCT ESQL LINQ EntityClient Data Provider

Internal caching mechanisms
Context metadata, etc. (app-domain level)
Materialized objects (context level, first level cache)
EntitySQL queries (app-domain level)
Linq queries (when compiled only)
ADO.NET providers internal caching
No second level caching like in NHibernate

Main performance losses
Infrastructure initialization
Mapping overhead (inheritance, complex mapping)
Query analysis
SQL generation
Materialization

Performance considerations
Views pre-generation (EF only)
Tracking vs. no tracking
Objects materialization and context-level caching
Linq queries compilation
Linq to Entities vs. EntitySQL (EF only)
Lazy vs. eager loading
Data modification
SQL generation

Tests suite and tools
Northwind database (yeah!)
Data retrieval tests:
simple data retrieval
advanced data retrieval (lazy loading)
advanced data retrieval (optimal)
Data modification tests
simple modification (10)
advanced modification (with relations, 10)
heavy modification (1000)

Initialization and views pre-generation
Context data (metadata, etc.) are cached in the app-domain
Connections are opened when needed
Views can be pre-generated for EF: EdmGen.exe
Use it to avoid cold start
207 38 12 Time, ms. EF L2S Readers Data Access

Tracking vs. no tracking
Tracking is used for:
Identity Map for the materialized objects
tracking changes of the materialized objects
No Tracking can be used:
when you don’t need to modify objects
61 138 25 EF (no tracking) 79 30 20 L2S (no tracking) 140 98 33 Advanced (lazy) 88 50 EF 83 23 Advanced (optimal) 23 20 Simple L2S Readers Data Access

Objects materialization and context-level caching
Materialization is:
creation of the objects in memory
cost-expensive (40-70% of the query)
Created objects are saved in the context (when Tracking)
To create context for every query or to use the same context for few queries? What is better?
76.9 54.5 36.1 EF (one) 77.9 36.6 13.8 L2S (one) 148 107.4 35.2 Advanced (lazy) 79.8 54.1 EF (many) 79.2 24.2 Advanced (optimal) 23.8 23.3 Simple L2S (many) Readers Data Access

Linq queries compilation
EntitySQL queries are cached
Linq to Entities queries are not cached
Every Linq query can be compiled and thus “cached”
42 109 4 2 EF (compiled) 63 97 21 L2S (compiled) 137 102 Advanced (lazy) 82 48 EF 85 Advanced (optimal) 23 Simple L2S Data Access

Linq to Entities vs. EntitySQL
What is better to use and when?
Linq to Entities:
type safety
easy-to-use, code completion
EntitySQL:
similar to SQL, flexible
low level => faster
32 98 44 EntitySQL 42 109 4 2 Linq to Entities (compiled ) 137 Advanced (lazy) 82 48 Linq to Entities Advanced (optimal) Simple Data Access

Lazy vs. eager loading
Eager loading is resource-consuming
Lazy loading is time-consuming
L2S has implicit lazy loading built-in
EF has explicit lazy loading built-in
It is always a dilemma… Get what you really need!
85 102 L2S 63 97 L2S (compiled) 32 98 EntitySQL 42 109 Linq to Entities (compiled ) 137 Advanced (lazy) 82 Linq to Entities Advanced (eager) Data Access

Data modification
L2S and EF contexts are Units of Work:
get => change => save all
Only when tracked
2,952 156 52 EF 12,075 268 153 L2S 75 Advanced 2,285 42 Commands Heavy Simple Data Modification

SQL generation
Get your SQL profilers ready!
33% 33% 33% Simple retrieval N/A N/A N/A Advanced retrieval (lazy) 24% 55% 21% Advanced retrieval (optimal) N/A N/A 33% EF N/A N/A 33% L2S N/A Advanced modification N/A 33% Readers/ Commands Heavy modification Simple modification Queries

Performance advices
choose the appropriate data access technology
make views pre-generation when possible
use the context as long as possible but be aware of memory overload and concurrency issues
turn off tracking when it can be done
use Linq queries compilation for complex queries
use eager loading when you know what you need to get
use EntitySQL for most time-cost operations
be careful with data modification
do not afraid to check the generated SQL, consider using indexes when possible

Q&A
Go ahead!

Useful links
http://msdn.microsoft.com/en-us/library/cc853327.aspx
http://blogs.msdn.com/adonet/archive/2008/03/27/ado-net-entity-framework-performance-comparison.aspx
http://blogs.msdn.com/adonet/archive/2006/08/21/710862.aspx
http://blogs.msdn.com/adonet/archive/2007/02/14/entity-client.aspx
http://blogs.msdn.com/adonet/archive/2007/05/30/entitysql.aspx
http://blogs.msdn.com/adonet/
http://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/2007/08/03/9558.aspx
http://oakleafblog.blogspot.com/2007/08/mike-taulty-compares-linq-to-sql-and.html
http://blogs.msdn.com/ricom/archive/2007/06/22/dlinq-linq-to-sql-performance-part-1.aspx
http://www.code-magazine.com/article.aspx?quickid=0712042&page=1
http://msdn.microsoft.com/ru-ru/magazine/cc163399.aspx

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Ling to SQL and Entity Framework performance analysis

by Alexander Konduforov on Jan 24, 2009

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Ling to SQL and Entity Framework performance analysis — Presentation Transcript