Performance

Jump to bottomEditNew page
Martin S. Johansen edited this page Mar 31, 2014 · 5 revisions

Written by Martin S. Johansen

The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.

The basics - Deferred execution

Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.

Lets say you want to fetch all rows which matches a title:

varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));

Will translate into EF doing the following query:

SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]

That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:

SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'

is a much more efficient database-query.

Selecting what you need

In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():

varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();

Will translate into EF doing the following query:

SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'

In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.

Avoid calling database to often with eager loading

(ToDo)

Track changes only when you need it

One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog

Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:

varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));

Use AddRange / RemoveRange (Since EF 6.1)

These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.

Map class-composition to complex types to avoid database relations (Code First)

(ToDo)

Use TPH (Table per Hierarchy) to avoid database relations (Code First)

(ToDo)

Create database indexes

Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.

Creating a view in EF can be done fluent api this:

publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}

Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:

protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}

Database views and stored procedures

(ToDo)

Add a custom footer
Add a custom sidebar

Clone this wiki locally

, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

Skip to content
Performance
Jump to bottomEditNew page

Martin S. Johansen edited this page Mar 31, 2014
·
5 revisions
Written by Martin S. Johansen
The performance of Entity Framework has evolved since the first versions, since version 4.1 the performance has steadily been getting better. EF is till a young ORM compared to other ORMs but with version 6.1 the performance is finally getting there. Still, there are some need-to-know techniques in order to get EF to perform. There is a different techniques regarding Code First / Model First / Database First, but all variants share the same API for calling queries, and all use deferred execution and all use the same LINQ-provider and the extension methods for calling the database. There are som scenarios where database views or stored procedures can/must be used in order to get good performance.
The basics - Deferred execution
Calling a repository-query and using ToList or ToArray will force the query to execute to the database and fetch all data to memory. This is fine if you really want all the data in memory, but sometimes you really only need a few rows and not all the data in every row. Some expressions cannot be evaluated and converted to SQL, using ToList before the expression seems like the only possibility, but one can use Select() to avoid this.
Lets say you want to fetch all rows which matches a title:
varmatches=bookRepository.Set.ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
That is not very efficient when having lots of books in the database, removing the ToList() (or putting tha ToList() last), translates into:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title], [Extent1].[Isbn] AS [Isbn], [Extent1].[Description] AS [Description], [Extent1].[Publisher_Id] AS [Publisher_Id]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Title] LIKE N'%Hitchhiker''s%'
is a much more efficient database-query.
Selecting what you need
In the previous example, we fetched books matching a title. When EF does a query, the default is to select all the columns in the entity, that is sometimes more than you need. Lets say you want to display all the titles that matches the title, and also get the key (Id) so that you can link to a page for more details. The more efficient approach here is to use Select():
varmatches=bookRepository.Set.Where(b =>b.Title.Contains("Hitchhiker's")).Select(b =>new{b.Id,b.Title}).ToList();
Will translate into EF doing the following query:
SELECT [Extent1].[Id] AS [Id], [Extent1].[Title] AS [Title]
FROM [dbo].[Book] AS [Extent1]
WHERE [Extent1].[Name] LIKE N'%Hitchhiker''s%'
In this example there where only a few columns, but with tables with many columns or with many relations, selecting all columns all the time will have a huge performance hit. When relations are included in the query, all the related columns are included.
Avoid calling database to often with eager loading
(ToDo)
Track changes only when you need it
One of the biggest performance hits in EF is change tracking. Entity Framework caches the DbContext and keep tracks of the entity state.

Source: Frans Bauma's Blog
Use AsNoTracking() when reading data you don't need to track! For example, when displaying a list of books you are not going to modify after reading, call AsNoTracking() as a part of the reading query:
varmatches=bookRepository.Set.AsNoTracking().ToList().Where(b =>b.Title.Contains("Hitchhiker's"));
Use AddRange / RemoveRange (Since EF 6.1)
These methods execute much faster than adding or removing a single object at a time because, by default, Entity Framework calls DetectChanges in each Add and Remove method. With the Range methods, you can handle multiple objects while DetectChanges is called only once, improving performance dramatically.
Map class-composition to complex types to avoid database relations (Code First)
(ToDo)
Use TPH (Table per Hierarchy) to avoid database relations (Code First)
(ToDo)
Create database indexes
Some queries will benefit from indexes, a full table scan will take much longer time to execute than querying an index. This is especially true for queries with multiple joins. Analyse queries to find which one who will benefit from indexes.
Creating a view in EF can be done fluent api this:
publicclassBookMap:EntityTypeConfiguration<Book>{publicBookMap(){HasIndex(c =>c.Publisher);}}
Note: In Code First since version 6.01, EF will by default create indexes for all foreign keys. If you want to turn this feature of, you can remove the convention like this:
protectedoverridevoidOnModelCreating(DbModelBuildermodelBuilder){modelBuilder.Conventions.Remove<ForeignKeyIndexConvention>();}
Database views and stored procedures
(ToDo)
 Add a custom footer

 Add a custom sidebar

Clone this wiki locally