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  • Lazy Loading,Eager Loading,Explicit Loading in Entity Framework 4

    - by nikolaosk
    This is going to be the ninth post of a series of posts regarding ASP.Net and the Entity Framework and how we can use Entity Framework to access our datastore. You can find the first one here , the second one here , the third one here , the fourth one here , the fifth one here ,the sixth one here ,the seventh one here and the eighth one here . I have a post regarding ASP.Net and EntityDataSource . You can read it here .I have 3 more posts on Profiling Entity Framework applications. You can have a...(read more)

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  • rails named_scope ignores eager loading

    - by Craig
    Two models (Rails 2.3.8): User; username & disabled properties; User has_one :profile Profile; full_name & hidden properties I am trying to create a named_scope that eliminate the disabled=1 and hidden=1 User-Profiles. The User model is usually used in conjunction with the Profile model, so I attempt to eager-load the Profile model (:include = :profile). I created a named_scope on the User model called 'visible': named_scope :visible, { :joins => "INNER JOIN profiles ON users.id=profiles.user_id", :conditions => ["users.disabled = ? AND profiles.hidden = ?", false, false] } I've noticed that when I use the named_scope in a query, the eager-loading instruction is ignored. Variation 1 - User model only: # UserController @users = User.find(:all) # User's Index view <% for user in @users %> <p><%= user.username %></p> <% end %> # generates a single query: SELECT * FROM `users` Variation 2 - use Profile model in view; lazy load Profile model # UserController @users = User.find(:all) # User's Index view <% for user in @users %> <p><%= user.username %></p> <p><%= user.profile.full_name %></p> <% end %> # generates multiple queries: SELECT * FROM `profiles` WHERE (`profiles`.user_id = 1) ORDER BY full_name ASC LIMIT 1 SHOW FIELDS FROM `profiles` SELECT * FROM `profiles` WHERE (`profiles`.user_id = 2) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 3) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 4) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 5) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 6) ORDER BY full_name ASC LIMIT 1 Variation 3 - eager load Profile model # UserController @users = User.find(:all, :include => :profile) #view; no changes # two queries SELECT * FROM `users` SELECT `profiles`.* FROM `profiles` WHERE (`profiles`.user_id IN (1,2,3,4,5,6)) Variation 4 - use name_scope, including eager-loading instruction #UserConroller @users = User.visible(:include => :profile) #view; no changes # generates multiple queries SELECT `users`.* FROM `users` INNER JOIN profiles ON users.id=profiles.user_id WHERE (users.disabled = 0 AND profiles.hidden = 0) SELECT * FROM `profiles` WHERE (`profiles`.user_id = 1) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 2) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 3) ORDER BY full_name ASC LIMIT 1 SELECT * FROM `profiles` WHERE (`profiles`.user_id = 4) ORDER BY full_name ASC LIMIT 1 Variation 4 does return the correct number of records, but also appears to be ignoring the eager-loading instruction. Is this an issue with cross-model named scopes? Perhaps I'm not using it correctly. Is this sort of situation handled better by Rails 3?

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  • Help me understand Rails eager loading

    - by aaronrussell
    I'm a little confused as to the mechanics of eager loading in active record. Lets say a Book model has many Pages and I fetch a book using this query: @book = Book.find book_id, :include => :pages Now this where I'm confused. My understanding is that @book.pages is already loaded and won't execute another query. But suppose I want to find a specific page, what would I do? @book.pages.find page_id # OR... @book.pages.to_ary.find{|p| p.id == page_id} Am I right in thinking that the first example will execute another query, and therefore making the eager loading pointless, or is active record clever enough to know that it doesn't need to do another query? Also, my second question, is there an argument that in some cases eager loading is more intensive on the database and sometimes multiple small queries will be more efficient that a single large query? Thanks for your thoughts.

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  • Eager loading vs. many queries with PHP, SQLite

    - by Mike
    I have an application that has an n+1 query problem, but when I implemented a way to load the data eagerly, I found absolutely no performance gain. I do use an identity map, so objects are only created once. Here's a benchmark of ~3000 objects. first query + first object creation: 0.00636100769043 sec. memory usage: 190008 bytes iterate through all objects (queries + objects creation): 1.98003697395 sec. memory usage: 7717116 bytes And here's one when I use eager loading. query: 0.0881109237671 sec. memory usage: 6948004 bytes object creation: 1.91053009033 sec. memory usage: 12650368 bytes iterate through all objects: 1.96605396271 sec. memory usage: 12686836 bytes So my questions are Is SQLite just magically lightning fast when it comes to small queries? (I'm used to working with MySQL.) Does this just seem wrong to anyone? Shouldn't eager loading have given much better performance?

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  • Eager load this rails association

    - by dombesz
    Hi, I have rails app which has a list of users. I have different relations between users, for example worked with, friend, preferred. When listing the users i have to decide if the current user can add a specific user to his friends. -if current_user.can_request_friendship_with(user) =add_to_friends(user) -else =remove_from_friends(user) -if current_user.can_request_worked_with(user) =add_to_worked_with(user) -else =remove_from_worked_with(user) The can_request_friendship_with(user) looks like: def can_request_friendship_with(user) !self.eql?(user) && !self.friendships.find_by_friend_id(user) end My problem is that this means in my case 4 query per user. Listing 10 users means 40 query. Could i somehow eager load this?

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  • Eager loading OneToMany in Hibernate with JPA2

    - by pihentagy
    I have a simple @OneToMany between Person and Pet entities: @OneToMany(mappedBy="owner", cascade=CascadeType.ALL, fetch=FetchType.EAGER) public Set<Pet> getPets() { return pets; } I would like to load all Persons with associated Pets. So I came up with this (inside a test class): @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration public class AppTest { @Test @Rollback(false) @Transactional(readOnly = false) public void testApp() { CriteriaBuilder qb = em.getCriteriaBuilder(); CriteriaQuery<Person> c = qb.createQuery(Person.class); Root<Person> p1 = c.from(Person.class); SetJoin<Person, Pet> join = p1.join(Person_.pets); TypedQuery<Person> q = em.createQuery(c); List<Person> persons = q.getResultList(); for (Person p : persons) { System.out.println(p.getName()); for (Pet pet : p.getPets()) { System.out.println("\t" + pet.getNick()); } } However, turning the SQL logging on shows, that it executes 3 queries (having 2 Persons in the DB). Hibernate: select person0_.id as id0_, person0_.name as name0_, person0_.sex as sex0_ from Person person0_ inner join Pet pets1_ on person0_.id=pets1_.owner_id Hibernate: select pets0_.owner_id as owner3_0_1_, pets0_.id as id1_, pets0_.id as id1_0_, pets0_.nick as nick1_0_, pets0_.owner_id as owner3_1_0_ from Pet pets0_ where pets0_.owner_id=? Hibernate: select pets0_.owner_id as owner3_0_1_, pets0_.id as id1_, pets0_.id as id1_0_, pets0_.nick as nick1_0_, pets0_.owner_id as owner3_1_0_ from Pet pets0_ where pets0_.owner_id=? Any tips? Thanks Gergo

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  • How can I Include Multiples Tables in my linq to entities eager loading using mvc4 C#

    - by EBENEZER CURVELLO
    I have 6 classes and I try to use linq to Entities to get the SiglaUF information of the last deeper table (in the view - MVC). The problem is I receive the following error: "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection." The view is like that: > @model IEnumerable<DiskPizzaDelivery.Models.EnderecoCliente> > @foreach (var item in Model) { > @Html.DisplayFor(modelItem => item.CEP.Cidade.UF.SiglaUF) > } The query that i use: var cliente = context.Clientes .Include(e => e.Enderecos) .Include(e1 => e1.Enderecos.Select(cep => cep.CEP)) .SingleOrDefault(); The question is: How Can I improve this query to pre loading (eager loading) "Cidade" and "UF"? See below the classes: public partial class Cliente { [Key] [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] public int IdCliente { get; set; } public string Email { get; set; } public string Senha { get; set; } public virtual ICollection<EnderecoCliente> Enderecos { get; set; } } public partial class EnderecoCliente { public int IdEndereco { get; set; } public int IdCliente { get; set; } public string CEPEndereco { get; set; } public string Numero { get; set; } public string Complemento { get; set; } public string PontoReferencia { get; set; } public virtual Cliente Cliente { get; set; } public virtual CEP CEP { get; set; } } public partial class CEP { public string CodCep { get; set; } public string Tipo_Logradouro { get; set; } public string Logradouro { get; set; } public string Bairro { get; set; } public int CodigoUF { get; set; } public int CodigoCidade { get; set; } public virtual Cidade Cidade { get; set; } } public partial class Cidade { public int CodigoCidade { get; set; } public string NomeCidade { get; set; } public int CodigoUF { get; set; } public virtual ICollection<CEP> CEPs { get; set; } public virtual UF UF { get; set; } public virtual ICollection<UF> UFs { get; set; } } public partial class UF { public int CodigoUF { get; set; } public string SiglaUF { get; set; } public string NomeUF { get; set; } public int CodigoCidadeCapital { get; set; } public virtual ICollection<Cidade> Cidades { get; set; } public virtual Cidade Cidade { get; set; } } var cliente = context.Clientes .Where(c => c.Email == email) .Where(c => c.Senha == senha) .Include(e => e.Enderecos) .Include(e1 => e1.Enderecos.Select(cep => cep.CEP)) .SingleOrDefault(); Thanks!

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  • How to eager load in WCF Ria Services/Linq2SQLDomainModel

    - by Aggelos Mpimpoudis
    I have a databound grid at my view (XAML) and the Itemsource points to a ReportsCollection. The Reports entity has three primitives and some complex types. These three are shown as expected at datagrid. Additionally the Reports entity has a property of type Store. When loading Reports via GetReports domain method, I quickly figure out that only primitives are returned and not the whole graph of some depth. So, as I wanted to load the Store property too, I made this alteration at my domain service: public IQueryable<Report> GetReports() { return this.ObjectContext.Reports.Include("Store"); } From what I see at the immediate window, store is loaded as expected, but when returned to client is still pruned. How can this be fixed? Thank you!

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  • Eager-loading association count with Arel (Rails 3)

    - by Matchu
    Simple task: given that an article has many comments, be able to display in a long list of articles how many comments each article has. I'm trying to work out how to preload this data with Arel. The "Complex Aggregations" section of the README file seems to discuss that type of situation, but it doesn't exactly offer sample code, nor does it offer a way to do it in two queries instead of one joined query, which is worse for performance. Given the following: class Article has_many :comments end class Comment belongs_to :article end How can I preload for an article set how many comments each has?

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  • Problem with eager load polymorphic associations using Linq and NHibernate

    - by Voislav
    Is it possible to eagerly load polymorphic association using Linq and NH? For example: Company is base class, Department is inherited from Company, and Company has association Employees to the User (one-to-many) and also association to the Country (many-to-one). Here is mapping part related to inherited class (without User and Country classes): <class name="Company" discriminator-value="Company"> <id name="Id" type="int" unsaved-value="0" access="nosetter.camelcase-underscore"> <generator class="native"></generator> </id> <discriminator column="OrganizationUnit" type="string" length="10" not-null="true"/> <property name="Name" type="string" length="50" not-null="true"/> <many-to-one name="Country" class="Country" column="CountryId" not-null ="false" foreign-key="FK_Company_CountryId" access="field.camelcase-underscore" /> <set name="Departments" inverse="true" lazy="true" access="field.camelcase-underscore"> <key column="DepartmentParentId" not-null="false" foreign-key="FK_Department_DepartmentParentId"></key> <one-to-many class="Department"></one-to-many> </set> <set name="Employees" inverse="true" lazy="true" access="field.camelcase-underscore"> <key column="CompanyId" not-null="false" foreign-key="FK_User_CompanyId"></key> <one-to-many class="User"></one-to-many> </set> <subclass name="Department" extends="Company" discriminator-value="Department"> <many-to-one name="DepartmentParent" class="Company" column="DepartmentParentId" not-null ="false" foreign-key="FK_Department_DepartmentParentId" access="field.camelcase-underscore" /> </subclass> </class> I do not have problem to eagerly load any of the association on the Company: Session.Query<Company>().Where(c => c.Name == "Main Company").Fetch(c => c.Country).Single(); Session.Query<Company>().Where(c => c.Name == "Main Company").FetchMany(c => c.Employees).Single(); Also, I could eagerly load not-polymorphic association on the department: Session.Query<Department>().Where(d => d.Name == "Department 1").Fetch(d => d.DepartmentParent).Single(); But I get NullReferenceException when I try to eagerly load any of the polymorphic association (from the Department): Assert.Throws<NullReferenceException>(() => Session.Query<Department>().Where(d => d.Name == "Department 1").Fetch(d => d.Country).Single()); Assert.Throws<NullReferenceException>(() => Session.Query<Department>().Where(d => d.Name == "Department 1").FetchMany(d => d.Employees).Single()); Am I doing something wrong or this is not supported yet?

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  • Rails eager loading

    - by Dimitar Vouldjeff
    HI, I have a Test model, which has_many questions, and Question, which has_many answers... When I make a query for a Test with :include = [:questions, {:questions = :answers}] ActiveRecord makes two more queries to fetch the questions and then to fetch the answers - it doesn`t join them!!! When I do the query with :joins ActiveRecord makes the query, but later when I need the Test.questions or Test.questions.answers ActiveRecord makes again those 2 extra queries!!! And later when I enumerate the questions or answers in the log I see other queries for each object, but it has Cache tag... Is this normal?

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  • GAE datastore eager loading in python api

    - by tomus
    I have two models in relation one-to-many: class Question(db.Model): questionText = db.StringProperty(multiline=False) class Answer(db.Model): answerText = db.StringProperty(multiline=False) question = db.ReferenceProperty(Question, collection_name='answers') I have front-end implemented in Flex and use pyamf to load data. When i try to load all answers with related questions all works as desired and I can access field answer.question however in case of loading questions (e.g. by Questions.all() ), 'question.answers' remains empty/null (though on server/python side I can revise question.answers without problem - probably after lazy-loading). So is it possible to load all questions along with answers ? (I know this is possible in JPA Java api but what about python ?) Shoud I use additional setting, GQL query or django framework to make it work ?

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  • How to eager fetch a child collection while joining child collection entities to an association

    - by ShaneC
    Assuming the following fictional layout Dealership has many Cars has a Manufacturer I want to write a query that says get me a Dealership with a Name of X and also get the Cars collection but use a join against the manufacturer when you do so. I think this would require usage of ICriteria. I'm thinking something like this.. var dealershipQuery = Session.CreateCriteria< Dealership>("d") .Add(Restrictions.InsenstiveLike("d.Name", "Foo")) .CreateAlias("d.Cars", "c") .SetFetchMode("d.Cars", FetchMode.Select) .SetFetchMode("c.Manufacturer", FetchMode.Join) .UniqueResult< Dealership>(); But the resulting query looks nothing like I would have expected. I'm starting to think a DetachedCriteria may be required somewhere but I'm not sure. Thoughts?

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  • Singleton with eager initialization

    - by jesper
    I have class X that takes much time to initialize itself. I want to make that class singleton and force its creation when rails application starts. I've made the singleton: class X @@instance = nil def self.instance if @@instance.nil? @@instance = X.new puts 'CREATING' end return @@instance end private_class_method :new end The problem is that every time I use this class I see 'CREATING' in logs. I've tried to put creation of class in initializers directory but it doesn't work either.

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  • Operator of the Week - Spools, Eager Spool

    For the fifth part of Fabiano's mission to describe the major Showplan Operators used by SQL Server's Query Optimiser, he introduces the spool operators and particularly the Eager Spool, explains blocking and non-blocking and then describes how the Halloween Problem is avoided.

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  • Eager to Learn more about MySQL?(Week 40)

    - by rituchhibber
    Are you a SQL programmer eager to know more?Oracle University is pleased to announce the availability of a new course in Training on Demand format : MySQL Performance Tuning.Why wait to get the training you need? Learn Oracle from Oracle today. Check out the demo to see how it works.Take a look at the new Training on Demand  MySQL Certification Packages.Please note: your OPN discount is applied to the standard price shown on the website.For more information, assistance and bookings contact your local Oracle University Service Desk.

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  • Eager to Learn More About Oracle Solaris 11?

    - by tfryer
    Are you a Solaris 11 System Administrator eager to know more? Oracle University is pleased to announce the release of two new courses: Solaris 11 ZFS Administration Oracle Solaris 11 Zones Administration Remember: your OPN discount is added to the standard prices shown on the website. Also check out the updated Oracle Solaris 11 Learning Path. For more information, assistance and bookings, contact your local Oracle University Service Desk.

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  • How do I disable "eager" validation entirely using jquery validate ?

    - by Kevin J
    Is there a way to disable "eager" validation using the jquery.validate plugin? Either through an option in the script or as a hack? "Eager" validation kicks in once the form has been validated once - after that, invalid fields are validated onfocusout. I want to disable this behavior, and change my forms to only be validated when the submit button is pressed. I don't mind hacking through the validate script itself also, so if that's what the solution requires that's acceptable.

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  • Organizing Eager Queries in an ObjectContext

    - by Nix
    I am messing around with Entity Framework 3.5 SP1 and I am trying to find a cleaner way to do the below. I have an EF model and I am adding some Eager Loaded entities and i want them all to reside in the "Eager" property in the context. We originally were just changing the entity set name, but it seems a lot cleaner to just use a property, and keep the entity set name in tact. Example: Context - EntityType - AnotherType - Eager (all of these would have .Includes to pull in all assoc. tables) - EntityType - AnotherType Currently I am using composition but I feel like there is an easier way to do what I want. namespace Entities{ public partial class TestObjectContext { EagerExtensions Eager { get;set;} public TestObjectContext(){ Eager = new EagerExtensions (this); } } public partial class EagerExtensions { TestObjectContext context; public EagerExtensions(TestObjectContext _context){ context = _context; } public IQueryable<TestEntity> TestEntity { get { return context.TestEntity .Include("TestEntityType") .Include("Test.Attached.AttachedType") .AsQueryable(); } } } } public class Tester{ public void ShowHowIWantIt(){ TestObjectContext context= new TestObjectContext(); var query = from a in context.Eager.TestEntity select a; } }

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  • How to eager load sibling data using LINQ to SQL?

    - by Scott
    The goal is to issue the fewest queries to SQL Server using LINQ to SQL without using anonymous types. The return type for the method will need to be IList<Child1>. The relationships are as follows: Parent Child1 Child2 Grandchild1 Parent Child1 is a one-to-many relationship Child1 Grandchild1 is a one-to-n relationship (where n is zero to infinity) Parent Child2 is a one-to-n relationship (where n is zero to infinity) I am able to eager load the Parent, Child1 and Grandchild1 data resulting in one query to SQL Server. This query with load options eager loads all of the data, except the sibling data (Child2): DataLoadOptions loadOptions = new DataLoadOptions(); loadOptions.LoadWith<Child1>(o => o.GrandChild1List); loadOptions.LoadWith<Child1>(o => o.Parent); dataContext.LoadOptions = loadOptions; IQueryable<Child1> children = from child in dataContext.Child1 select child; I need to load the sibling data as well. One approach I have tried is splitting the query into two LINQ to SQL queries and merging the result sets together (not pretty), however upon accessing the sibling data it is lazy loaded anyway. Adding the sibling load option will issue a query to SQL Server for each Grandchild1 and Child2 record (which is exactly what I am trying to avoid): DataLoadOptions loadOptions = new DataLoadOptions(); loadOptions.LoadWith<Child1>(o => o.GrandChild1List); loadOptions.LoadWith<Child1>(o => o.Parent); loadOptions.LoadWith<Parent>(o => o.Child2List); dataContext.LoadOptions = loadOptions; IQueryable<Child1> children = from child in dataContext.Child1 select child; exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=1 exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=2 exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=3 exec sp_executesql N'SELECT * FROM [dbo].[Child2] AS [t0] WHERE [t0].[ForeignKeyToParent] = @p0',N'@p0 int',@p0=4 I've also written LINQ to SQL queries to join in all of the data in hopes that it would eager load the data, however when the LINQ to SQL EntitySet of Child2 or Grandchild1 are accessed it lazy loads the data. The reason for returning the IList<Child1> is to hydrate business objects. My thoughts are I am either: Approaching this problem the wrong way. Have the option of calling a stored procedure? My organization should not be using LINQ to SQL as an ORM? Any help is greatly appreciated. Thank you, -Scott

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  • why is this rails association loading individually after an eager load?

    - by codeman73
    I'm trying to avoid the N+1 queries problem with eager loading, but it's not working. The associated models are still being loaded individually. Here are the relevant ActiveRecords and their relationships: class Player < ActiveRecord::Base has_one :tableau end Class Tableau < ActiveRecord::Base belongs_to :player has_many :tableau_cards has_many :deck_cards, :through => :tableau_cards end Class TableauCard < ActiveRecord::Base belongs_to :tableau belongs_to :deck_card, :include => :card end class DeckCard < ActiveRecord::Base belongs_to :card has_many :tableaus, :through => :tableau_cards end class Card < ActiveRecord::Base has_many :deck_cards end and the query I'm using is inside this method of Player: def tableau_contains(card_id) self.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', self.tableau.id] contains = false for tableau_card in self.tableau.tableau_cards # my logic here, looking at attributes of the Card model, with # tableau_card.deck_card.card; # individual loads of related Card models related to tableau_card are done here end return contains end Does it have to do with scope? This tableau_contains method is down a few method calls in a larger loop, where I originally tried doing the eager loading because there are several places where these same objects are looped through and examined. Then I eventually tried the code as it is above, with the load just before the loop, and I'm still seeing the individual SELECT queries for Card inside the tableau_cards loop in the log. I can see the eager-loading query with the IN clause just before the tableau_cards loop as well. EDIT: additional info below with the larger, outer loop Here's the larger loop. It is inside an observer on after_save def after_save(pa) @game = Game.find(turn.game_id, :include => :goals) @game.players = Player.find :all, :include => [ {:tableau => (:tableau_cards)}, :player_goals ], :conditions => ['players.game_id =?', @game.id] for player in @game.players player.tableau.tableau_cards = TableauCard.find :all, :include => [ {:deck_card => (:card)}], :conditions => ['tableau_cards.tableau_id = ?', player.tableau.id] if(player.tableau_contains(card)) ... end end end

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  • What good books are out there on program execution models? [on hold]

    - by murungu
    Can anyone out there name a few books that address the topic of program execution models?? I want a book that can answer questions such as... What is the difference between interpreted and compiled languages and what are the performance consequences at runtime?? What is the difference between lazy evaluation, eager evaluation and short circuit evaluation?? Why would one choose to use one evaluation strategy over another?? How do you simulate lazy evaluation in a language that favours eager evaluation??

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  • Eager Loading more than 1 table in LinqtoSql

    - by Michael Freidgeim
    When I've tried in Linq2Sql to load table with 2 child tables, I've noticed, that multiple SQLs are generated. I've found that  it isa known issue, if you try to specify more than one to pre-load it just  picks which one to pre-load and which others to leave deferred (simply ignoring those LoadWith hints)There are more explanations in http://codebetter.com/blogs/david.hayden/archive/2007/08/06/linq-to-sql-query-tuning-appears-to-break-down-in-more-advanced-scenarios.aspxThe reason the relationship in your blog post above is generating multiple queries is that you have two (1:n) relationship (Customers->Orders) and (Orders->OrderDetails). If you just had one (1:n) relationship (Customer->Orders) or (Orders->OrderDetails) LINQ to SQL would optimize and grab it in one query (using a JOIN).  The alternative -to use SQL and POCO classes-see http://stackoverflow.com/questions/238504/linq-to-sql-loading-child-entities-without-using-dataloadoptions?rq=1Fortunately the problem is not applicable to Entity Framework, that we want to use in future development instead of Linq2SqlProduct firstProduct = db.Product.Include("OrderDetail").Include("Supplier").First(); ?

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  • Rails - eager load the number of associated records, but not the record themselves.

    - by Max Williams
    I have a page that's taking ages to render out. Half of the time (3 seconds) is spent on a .find call which has a bunch of eager-loaded associations. All i actually need is the number of associated records in each case, to display in a table: i don't need the actual records themselves. Is there a way to just eager load the count? Here's a simplified example: @subjects = Subject.find(:all, :include => [:questions]) In my table, for each row (ie each subject) i just show the values of the subject fields and the number of associated questions for each subject. Can i optimise the above find call to suit these requirements? I thought about using a group field but my full call has a few different associations included, with some second-order associations, so i don't think group by will work. @subjects = Subject.find(:all, :include => [{:questions => :tags}, {:quizzes => :tags}], :order => "subjects.name") :tags in this case is a second-order association, via taggings. Here's my associations in case it's not clear what's going on. Subject has_many :questions has_many :quizzes Question belongs_to :subject has_many :taggings has_many :tags, :through => :taggings Quiz belongs_to :subject has_many :taggings has_many :tags, :through => :taggings Grateful for any advice - max

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