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• What'd be a good pattern on Doctrine to have multiple languages

  - by PERR0_HUNTER

  Hi! I have this challenge which consist in having a system that offers it's content in multiple languages, however a part of the data contained in the system is not translatable such as dates, ints and such. I mean if I have a content on the following YAML Corporativos: columns: nombre: type: string(254) notnull: true telefonos: type: string(500) email: type: string(254) webpage: type: string(254) CorporativosLang: columns: corporativo_id: type: integer(8) notnull: true lang: type: string(16) fixed: false ubicacion: type: string() fixed: false unsigned: false primary: false notnull: true autoincrement: false contacto: type: string() fixed: false unsigned: false primary: false notnull: true autoincrement: false tipo_de_hoteles: type: string(254) fixed: false unsigned: false primary: false notnull: true autoincrement: false paises: type: string() fixed: false unsigned: false primary: false notnull: true autoincrement: false relations: Corporativo: class: Corporativos local: corporativo_id foreign: id type: one foreignAlias: Data This would allow me to have different corporative offices, however the place of the corp, the contact and other things can be translate into a different language (lang) Now this code here would create me a brand new corporative office with 2 translations $corporativo = new Corporativos(); $corporativo->nombre = 'Duck Corp'; $corporativo->telefonos = '66303713333'; $corporativo->email = '[email protected]'; $corporativo->webpage = 'http://quack.com'; $corporativo->Data[0]->lang = 'en'; $corporativo->Data[0]->ubicacion = 'zomg'; $corporativo->Data[1]->lang = 'es'; $corporativo->Data[1]->ubicacion = 'zomg amigou'; the thing now is I don't know how to retrieve this data in a more friendly way, because if I'd like to access my Corporative info in english I'd had to run DQL for the corp and then another DQL for the specific translation in english, What I'd love to do is have my translatable fields available in the root so I could simply access them $corporativo = new Corporativos(); $corporativo->nombre = 'Duck Corp'; $corporativo->telefonos = '66303713333'; $corporativo->email = '[email protected]'; $corporativo->webpage = 'http://quack.com'; $corporativo->lang = 'en'; $corporativo->ubicacion = 'zomg'; this way the translatable fields would be mapped to the second table automatically. I hope I can explain my self clear :( any suggestions ?

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• Data denormalization and C# objects DB serialization

  - by Robert Koritnik

  I'm using a DB table with various different entities. This means that I can't have an arbitrary number of fields in it to save all kinds of different entities. I want instead save just the most important fields (dates, reference IDs - kind of foreign key to various other tables, most important text fields etc.) and an additional text field where I'd like to store more complete object data. the most obvious solution would be to use XML strings and store those. The second most obvious choice would be JSON, that usually shorter and probably also faster to serialize/deserialize... And is probably also faster. But is it really? My objects also wouldn't need to be strictly serializable, because JsonSerializer is usually able to serialize anything. Even anonymous objects, that may as well be used here. What would be the most optimal solution to solve this problem? Additional info My DB is highly normalised and I'm using Entity Framework, but for the purpose of having external super-fast fulltext search functionality I'm sacrificing a bit DB denormalisation. Just for the info I'm using SphinxSE on top of MySql. Sphinx would return row IDs that I would use to fast query my index optimised conglomerate table to get most important data from it much much faster than querying multiple tables all over my DB. My table would have columns like: RowID (auto increment) EntityID (of the actual entity - but not directly related because this would have to point to different tables) EntityType (so I would be able to get the actual entity if needed) DateAdded (record timestamp when it's been added into this table) Title Metadata (serialized data related to particular entity type) This table would be indexed with SPHINX indexer. When I would search for data using this indexer I would provide a series of EntityIDs and a limit date. Indexer would have to return a very limited paged amount of RowIDs ordered by DateAdded (descending). I would then just join these RowIDs to my table and get relevant results. So this won't actually be full text search but a filtering search. Getting RowIDs would be very fast this way and getting results back from the table would be much faster than comparing EntityIDs and DateAdded comparisons even though they would be properly indexed.

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• DataRelation Insert and ForeignKey

  - by Steve

  Guys, I have a winforms application with two DataGridViews displaying a master-detail relationship from my Person and Address tables. Person table has a PersonID field that is auto-incrementing primary key. Address has a PersonID field that is the FK. I fill my DataTables with DataAdapter and set Person.PersonID column's AutoIncrement=true and AutoIncrementStep=-1. I can insert records in the Person DataTable from the DataGridView. The PersonID column displays unique negative values for PersonID. I update the database by calling DataAdapter.Update(PersonTable) and the negative PersonIDs are converted to positive unique values automatically by SQL Server. Here's the rub. The Address DataGridView show the address table which has a DataRelation to Person by PersonID. Inserted Person records have the temporary negative PersonID. I can now insert records into Address via DataGridView and Address.PersonID is set to the negative value from the DataRelation mapping. I call Adapter.Update(AddressTable) and the negative PersonIDs go into the Address table breaking the relationship. How do you guys handle primary/foreign keys using DataTables and master-detail DataGridViews? Thanks! Steve EDIT: After more googling, I found that SqlDataAdapter.RowUpdated event gives me what I need. I create a new command to query the last id inserted by using @@IDENTITY. It works pretty well. The DataRelation updates the Address.PersonID field for me so it's required to Update the Person table first then update the Address table. All the new records insert properly with correct ids in place! Adapter = new SqlDataAdapter(cmd); Adapter.RowUpdated += (s, e) => { if (e.StatementType != StatementType.Insert) return; //set the id for the inserted record SqlCommand c = e.Command.Connection.CreateCommand(); c.CommandText = "select @@IDENTITY id"; e.Row[0] = Convert.ToInt32( c.ExecuteScalar() ); }; Adapter.Fill(this); SqlCommandBuilder sb = new SqlCommandBuilder(Adapter); sb.GetDeleteCommand(); sb.GetUpdateCommand(); sb.GetInsertCommand(); this.Columns[0].AutoIncrement = true; this.Columns[0].AutoIncrementSeed = -1; this.Columns[0].AutoIncrementStep = -1;

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• Release Process Improvements

  - by wallismark

  The process of creating a new build and releasing it to production is a critical step in the SDLC but it is often left as an afterthought and varies greatly from one company to the next. I'm hoping people will share improvements they have made to this process in their organisation so we can all takes steps to 'reduce the pain'. So the question is, specify one painful/time consuming part of your release process and what did you do to improve it? My example: at a previous employer all developers made database changes on one common development database. Then when it came to release time, we used Redgate's SQL Compare to generate a huge script from the differences between the Dev and QA databases. This works reasonably well but the problems with this approach are:- ALL changes in the Dev database are included, some of which may still be 'works in progress'. Sometimes developers made conflicting changes (that were not noticed until the release was in production) It was a time consuming and manual process to create and validate the script (by validate I mean, try to weed out issues like problem 1 and 2). When there were problems with the script (eg the order in which things were run such as creating a record which relies on a foreign key record which is in the script but not yet run) it took time to 'tweak' it so it ran smoothly. It's not an ideal scenario for Continuous Integration. So the solution was:- Enforce a policy of all changes to the database must be scripted. A naming convention was important for ensuring the correct running order of the scripts. Create/Use a tool to run the scripts at release time. Developers had their own copy of the database do develop against (so there was no more 'stepping on each others toes') The next release after we started this process was much faster with fewer problems, indeed the only problems found were due to people 'breaking the rules', eg not creating a script. Once the issues with releasing to QA were fixed, when it came time to release to production it was very smooth. We applied a few other changes (like introducing CI) but this was the most significant, overall we reduced release time from around 3 hours down to a max of 10-15 minutes.

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• Whats happening to my HTML?

  - by user156814

  I am making changes to my website, and I just noticed that things look different. In IE, the content doesnt center, theres a margin on my content, and the font looks bigger in chrome.. I ran it through Yahoo's HTML validator and the error I get is line 1 - Error: character "" not allowed in prolog. I believe that there may be some sort of whitespace being sent before the DOC TYPE, but I cant seem to fix it. The HTML looks fine in my text editor (Notepad++) so I dont know what the problem is. Im using a strict DOC Type. Everything was fine before I made any changes, but I cant pinpoint what caused the change. If it helps, I'm using a Framework (Kohana). My initial thought was that something was being sent to the browser by an echo or something, but I couldnt find any echo statements. I dont know what could be causing this... If you want to see any code or HTML just ask. Thanks. Heres the HTML (only head and doctype) via the page source in Google Chrome There seems to be some foreign characters in the source that I've never seen before, yet dont show up anywhere else (yahoo, or otherwise) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>Recent Debates - Clashing Thoughts</title> <meta http-equiv="Content-type" content="text/html; charset=utf-8" /> <meta http-equiv="Content-Language" content="en-us" /> <meta name="description" content="Clashing Thoughts is a great place to argue! Search topics you feel passionate about, pick where you stand on the issue and get your point across. The votes are tallied up for every debate so you can even see which side is most popular." /> <meta name="keywords" content="debates, arguments, topics, popular topics, popular debates, surveys, choices" /> <link rel="stylesheet" type="text/css" href="http://localhost/css/master.css" media="screen" /> <link rel="stylesheet" type="text/css" href="http://localhost/css/clashingthoughts.css" media="screen" /> <link rel="icon" type="image/x-icon" href="http://localhost/images/favicon.ico" /> <link rel="shortcut icon" type="image/x-icon" href="http://localhost/images/favicon.ico" /> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> </head>

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• Oracle sample data problems

  - by Jay

  So, I have this java based data trasformation / masking tool, which I wanted to test out on Oracle 10g. The good part with Oracle 10g is that you get a load of sample schemas with half a million records in some. The schemas are : SH, OE, HR, IX and etc. So, I installed 10g, found out that the installation scripts are under ORACLE_HOME/demo/scripts. I customized these scripts a bit to run in batch mode. That solves one half of my requirement - to create source data for my testing my data transformation software. The second half of the requirement is that I create the same schemas under different names (TR_HR, TR_OE and so on...) without any data. These schemas would represent my target schemas. So, in short, my software would pick up data from a table in a schema and load it up in to the same table in a different schema. Now, I have two issues in creating my target schema and emptying it. I would like this in a batch job. But the oracle scripts you get, the sample schema names are not configurable. So, I tried creating a script, replacing OE with TR_OE, HR with TR_HR and so on. However, this approach is kind of irritating coz the sample schemas are kind of complicated in the way they are created; Oracle creates synonyms, views, materialized views, data types and lot of weird stuff. I would like the target schemas (TR_HR, TR_OE,...) to be empty. But some of the schemas have circular references, which would not allow me to delete data. The only work around seems to be removing certain foreign keys, deleting data and then adding the constraints back. Is there any easy way to all this, without all this fuss? I would need a complicated data set for my testing (complicated as in tables with triggers, multiple hierarchies.. for instance.. a child table that has children up to 5 levels, a parent table that refers to an IOT table and an IOT table that refers to a non-IOT table etc..). The sample schemas are just about perfect from a data set perspective. The only challenge I see is in automating this whole process of loading up the source schemas, and then creating the target schemas and emptying them. Appreciate your help and suggestions.

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• Map One-To-One Relationship Doesn't Allow Inserting

  - by nfplee

  Hi, I'm trying to setup a one-to-one mapping from my Users to the UserDetails table. Say I have the following tables in my database: Users: - UserID (PK, Identity) - UserName - Password UsersDetails: - UserID (PK, FK) - FirstName - LastName I have created the following poco classes: public class User { public virtual int UserID { get; set; } public virtual string UserName { get; set; } public virtual string Password { get; set; } public virtual UserDetails Details { get; set; } } public class UserDetails { public virtual int UserID { get; set; } public virtual User User { get; set; } public virtual string FirstName { get; set; } public virtual string LastName { get; set; } public UserDetails() { } public UserDetails(User user) { User = user; } } Which are fluently mapped (please note the xml mapping is very similar and if all you know is the xml mapping then I would still appreciate you guidance): public class UserMap : ClassMap<User> { public UserMap() { Table("Users"); Id(x => x.UserID); Map(x => x.UserName); Map(x => x.Password); HasOne(x => x.Details) .Constrained() .Cascade.All(); } } public class UserDetailsMap : ClassMap<UserDetails> { public UserDetailsMap() { Table("UsersDetails"); Id(x => x.UserID) .GeneratedBy.Foreign("User"); HasOne(x => x.User) .Constrained(); Map(x => x.FirstName); Map(x => x.LastName); } } Everything displays correctly but if I say: var user = new User() { UserName = "Test", Password = "Test" }; user.Details = new UserDetails(user) { FirstName = "Test", LastName = "Test" }; session.Save(user); I get the error: "NHibernate.Id.IdentifierGenerationException: null id generated for: UserDetails." I'd really appreciate it if someone could show me what I've done wrong. Thanks

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• Linq-to-SQL: How to perform a count on a sub-select

  - by Peter Bridger

  I'm still trying to get my head round how to use LINQ-to-SQL correctly, rather than just writing my own sprocs. In the code belong a userId is passed into the method, then LINQ uses this to get all rows from the GroupTable tables matching the userId. The primary key of the GroupUser table is GroupUserId, which is a foreign key in the Group table. /// <summary> /// Return summary details about the groups a user belongs to /// </summary> /// <param name="userId"></param> /// <returns></returns> public List<Group> GroupsForUser(int userId) { DataAccess.KINv2DataContext db = new DataAccess.KINv2DataContext(); List<Group> groups = new List<Group>(); groups = (from g in db.Groups join gu in db.GroupUsers on g.GroupId equals gu.GroupId where g.Active == true && gu.UserId == userId select new Group { Name = g.Name, CreatedOn = g.CreatedOn }).ToList<Group>(); return groups; } } This works fine, but I'd also like to return the total number of Users who are in a group and also the total number of Contacts that fall under ownership of the group. Pseudo code ahoy! /// <summary> /// Return summary details about the groups a user belongs to /// </summary> /// <param name="userId"></param> /// <returns></returns> public List<Group> GroupsForUser(int userId) { DataAccess.KINv2DataContext db = new DataAccess.KINv2DataContext(); List<Group> groups = new List<Group>(); groups = (from g in db.Groups join gu in db.GroupUsers on g.GroupId equals gu.GroupId where g.Active == true && gu.UserId == userId select new Group { Name = g.Name, CreatedOn = g.CreatedOn, // ### This is the SQL I would write to get the data I want ### MemberCount = ( SELECT COUNT(*) FROM GroupUser AS GU WHERE GU.GroupId = g.GroupId ), ContactCount = ( SELECT COUNT(*) FROM Contact AS C WHERE C.OwnerGroupId = g.GroupId ) // ### End of extra code ### }).ToList<Group>(); return groups; } }

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• Historical / auditable database

  - by Mark

  Hi all, This question is related to the schema that can be found in one of my other questions here. Basically in my database I store users, locations, sensors amongst other things. All of these things are editable in the system by users, and deletable. However - when an item is edited or deleted I need to store the old data; I need to be able to see what the data was before the change. There are also non-editable items in the database, such as "readings". They are more of a log really. Readings are logged against sensors, because its the reading for a particular sensor. If I generate a report of readings, I need to be able to see what the attributes for a location or sensor was at the time of the reading. Basically I should be able to reconstruct the data for any point in time. Now, I've done this before and got it working well by adding the following columns to each editable table: valid_from valid_to edited_by If valid_to = 9999-12-31 23:59:59 then that's the current record. If valid_to equals valid_from, then the record is deleted. However, I was never happy with the triggers I needed to use to enforce foreign key consistency. I can possibly avoid triggers by using the extension to the "PostgreSQL" database. This provides a column type called "period" which allows you to store a period of time between two dates, and then allows you to do CHECK constraints to prevent overlapping periods. That might be an answer. I am wondering though if there is another way. I've seen people mention using special historical tables, but I don't really like the thought of maintainling 2 tables for almost every 1 table (though it still might be a possibility). Maybe I could cut down my initial implementation to not bother checking the consistency of records that aren't "current" - i.e. only bother to check constraints on records where the valid_to is 9999-12-31 23:59:59. Afterall, the people who use historical tables do not seem to have constraint checks on those tables (for the same reason, you'd need triggers). Does anyone have any thoughts about this? PS - the title also mentions auditable database. In the previous system I mentioned, there is always the edited_by field. This allowed all changes to be tracked so we could always see who changed a record. Not sure how much difference that might make. Thanks.

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• Applying Domain Model on top of Linq2Sql entities

  - by Thomas

  I am trying to practice the model first approach and I am putting together a domain model. My requirement is pretty simple: UserSession can have multiple ShoppingCartItems. I should start off by saying that I am going to apply the domain model interfaces to Linq2Sql generated entities (using partial classes). My requirement translates into three database tables (UserSession, Product, ShoppingCartItem where ProductId and UserSessionId are foreign keys in the ShoppingCartItem table). Linq2Sql generates these entities for me. I know I shouldn't even be dealing with the database at this point but I think it is important to mention. The aggregate root is UserSession as a ShoppingCartItem can not exist without a UserSession but I am unclear on the rest. What about Product? It is defiently an entity but should it be associated to ShoppingCartItem? Here are a few suggestion (they might all be incorrect implementations): public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItem> ShoppingCartItems{ get; set; } } public interface IShoppingCartItem { public Guid UserSessionId { get; set; } public int ProductId { get; set; } } Another one would be: public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItem> ShoppingCartItems{ get; set; } } public interface IShoppingCartItem { public Guid UserSessionId { get; set; } public IProduct Product { get; set; } } A third one is: public interface IUserSession { public Guid Id { get; set; } public IList<IShoppingCartItemColletion> ShoppingCartItems{ get; set; } } public interface IShoppingCartItemColletion { public IUserSession UserSession { get; set; } public IProduct Product { get; set; } } public interface IProduct { public int ProductId { get; set; } } I have a feeling my mind is too tightly coupled with database models and tables which is making this hard to grasp. Anyone care to decouple?

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• Castle ActiveRecord - schema generation without enforcing referential integrity?

  - by Simon

  Hi all, I've just started playing with Castle active record as it seems like a gentle way into NHibernate. I really like the idea of the database schema being generate from my classes during development. I want to do something similar to the following: [ActiveRecord] public class Camera : ActiveRecordBase<Camera> { [PrimaryKey] public int CameraId {get; set;} [Property] public int CamKitId {get; set;} [Property] public string serialNo {get; set;} } [ActiveRecord] public class Tripod : ActiveRecordBase<Tripod> { [PrimaryKey] public int TripodId {get; set;} [Property] public int CamKitId {get; set;} [Property] public string serialNo {get; set;} } [ActiveRecord] public class CameraKit : ActiveRecordBase<CameraKit> { [PrimaryKey] public int CamKitId {get; set;} [Property] public string description {get; set;} [HasMany(Inverse=true, Table="Cameras", ColumnKey="CamKitId")] public IList<Camera> Cameras {get; set;} [HasMany(Inverse=true, Table="Tripods", ColumnKey="CamKitId")] public IList<Camera> Tripods {get; set;} } A camerakit should contain any number of tripods and cameras. Camera kits exist independently of cameras and tripods, but are sometimes related. The problem is, if I use createschema, this will put foreign key constraints on the Camera and Tripod tables. I don't want this, I want to be able to to set CamKitId to null on the tripod and camera tables to indicate that it is not part of a CameraKit. Is there a way to tell activerecord/nhibernate to still see it as related, without enforcing the integrity? I was thinking I could have a cameraKit record in there to indicate "no camera kit", but it seems like oeverkill. Or is my schema wrong? Am I doing something I shouldn't with an ORM? (I've not really used ORMs much) Thanks!

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• Error using `loess.smooth` but not `loess` or `lowess`

  - by Sandy

  I need to smooth some simulated data, but occasionally run into problems when the simulated ordinates to be smoothed are mostly the same value. Here is a small reproducible example of the simplest case. > x <- 0:50 > y <- rep(0,51) > loess.smooth(x,y) Error in simpleLoess(y, x, w, span, degree, FALSE, FALSE, normalize = FALSE, : NA/NaN/Inf in foreign function call (arg 1) loess(y~x), lowess(x,y), and their analogue in MATLAB produce the expected results without error on this example. I am using loess.smooth here because I need the estimates evaluated at a set number of points. According to the documentation, I believe loess.smooth and loess are using the same estimation functions, but the former is an "auxiliary function" to handle the evaluation points. The error seems to come from a C function: > traceback() 3: .C(R_loess_raw, as.double(pseudovalues), as.double(x), as.double(weights), as.double(weights), as.integer(D), as.integer(N), as.double(span), as.integer(degree), as.integer(nonparametric), as.integer(order.drop.sqr), as.integer(sum.drop.sqr), as.double(span * cell), as.character(surf.stat), temp = double(N), parameter = integer(7), a = integer(max.kd), xi = double(max.kd), vert = double(2 * D), vval = double((D + 1) * max.kd), diagonal = double(N), trL = double(1), delta1 = double(1), delta2 = double(1), as.integer(0L)) 2: simpleLoess(y, x, w, span, degree, FALSE, FALSE, normalize = FALSE, "none", "interpolate", control$cell, iterations, control$trace.hat) 1: loess.smooth(x, y) loess also calls simpleLoess, but with what appears to be different arguments. Of course, if you vary enough of the y values to be nonzero, loess.smooth runs without error, but I need the program to run in even the most extreme case. Hopefully, someone can help me with one and/or all of the following: Understand why only loess.smooth, and not the other functions, produces this error and find a solution for this problem. Find a work-around using loess but still evaluating the estimate at a specified number of points that can differ from the vector x. For example, I might want to use only x <- seq(0,50,10) in the smoothing, but evaluate the estimate at x <- 0:50. As far as I know, using predict with a new data frame will not properly handle this situation, but please let me know if I am missing something there. Handle the error in a way that doesn't stop the program from moving onto the next simulated data set. Thanks in advance for any help on this problem.

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• Adding a generic image field onto a ModelForm in django

  - by Prairiedogg

  I have two models, Room and Image. Image is a generic model that can tack onto any other model. I want to give users a form to upload an image when they post information about a room. I've written code that works, but I'm afraid I've done it the hard way, and specifically in a way that violates DRY. Was hoping someone who's a little more familiar with django forms could point out where I've gone wrong. Update: I've tried to clarify why I chose this design in comments to the current answers. To summarize: I didn't simply put an ImageField on the Room model because I wanted more than one image associated with the Room model. I chose a generic Image model because I wanted to add images to several different models. The alternatives I considered were were multiple foreign keys on a single Image class, which seemed messy, or multiple Image classes, which I thought would clutter my schema. I didn't make this clear in my first post, so sorry about that. Seeing as none of the answers so far has addressed how to make this a little more DRY I did come up with my own solution which was to add the upload path as a class attribute on the image model and reference that every time it's needed. # Models class Image(models.Model): content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') image = models.ImageField(_('Image'), height_field='', width_field='', upload_to='uploads/images', max_length=200) class Room(models.Model): name = models.CharField(max_length=50) image_set = generic.GenericRelation('Image') # The form class AddRoomForm(forms.ModelForm): image_1 = forms.ImageField() class Meta: model = Room # The view def handle_uploaded_file(f): # DRY violation, I've already specified the upload path in the image model upload_suffix = join('uploads/images', f.name) upload_path = join(settings.MEDIA_ROOT, upload_suffix) destination = open(upload_path, 'wb+') for chunk in f.chunks(): destination.write(chunk) destination.close() return upload_suffix def add_room(request, apartment_id, form_class=AddRoomForm, template='apartments/add_room.html'): apartment = Apartment.objects.get(id=apartment_id) if request.method == 'POST': form = form_class(request.POST, request.FILES) if form.is_valid(): room = form.save() image_1 = form.cleaned_data['image_1'] # Instead of writing a special function to handle the image, # shouldn't I just be able to pass it straight into Image.objects.create # ...but it doesn't seem to work for some reason, wrong syntax perhaps? upload_path = handle_uploaded_file(image_1) image = Image.objects.create(content_object=room, image=upload_path) return HttpResponseRedirect(room.get_absolute_url()) else: form = form_class() context = {'form': form, } return direct_to_template(request, template, extra_context=context)

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• Any simple approaches for managing customer data change requests for global reference files?

  - by Kelly Duke

  For the first time, I am developing in an environment in which there is a central repository for a number of different industry standard reference data tables and many different customers who need to select records from these industry standard reference data tables to fill in foreign key information for their customer specific records. Because these industry standard reference files are utilized by all customers, I want to reserve Create/Update/Delete access to these records for global product administrators. However, I would like to implement a (semi-)automated interface by which specific customers could request record additions, deletions or modifications to any of the industry standard reference files that are shared among all customers. I know I need something like a "data change request" table specifying: user id, user request datetime, request type (insert, modify, delete), a user entered text explanation of the change request, the user request's current status (pending, declined, completed), admin resolution datetime, admin id, an admin entered text description of the resolution, etc. What I can't figure out is how to elegantly handle the fact that these data change requests could apply to dozens of different tables with differing table column definitions. I would like to give the customer users making these data change requests a convenient way to enter their proposed record additions/modifications directly into CRUD screens that look very much like the reference table CRUD screens they don't have write/delete permissions for (with an additional text explanation and perhaps request priority field). I would also like to give the global admins a tool that allows them to view all the outstanding data change requests for the users they oversee sorted by date requested or user/date requested. Upon selecting a data change request record off the list, the admin would be directed to another CRUD screen that would be populated with the fields the customer users requested for the new/modified industry standard reference table record along with customer's text explanation, the request status and the text resolution explanation field. At this point the admin could accept/edit/reject the requested change and if accepted the affected industry standard reference file would be automatically updated with the appropriate fields and the data change request record's status, text resolution explanation and resolution datetime would all also be appropriately updated. However, I want to keep the actual production reference tables as simple as possible and free from these extraneous and typically null customer change request fields. I'd also like the data change request file to aggregate all data change requests across all the reference tables yet somehow "point to" the specific reference table and primary key in question for modification & deletion requests or the specific reference table and associated customer user entered field values in question for record creation requests. Does anybody have any ideas of how to design something like this effectively? Is there a cleaner, simpler way I am missing? Thank you so much for reading.

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• NHibernate Mapping problem

  - by Bernard Larouche

  My database is being driven by my NHibernate mapping files. I have a Category class that looks like the following : public class Category { public Category() : this("") { } public Category(string name) { Name = name; SubCategories = new List<Category>(); Products = new HashSet<Product>(); } public virtual int ID { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } public virtual Category Parent { get; set; } public virtual bool IsDefault { get; set; } public virtual ICollection<Category> SubCategories { get; set; } public virtual ICollection<Product> Products { get; set; } and here is my Mapping file : <property name="Name" column="Name" type="string" not-null="true"/> <property name="IsDefault" column="IsDefault" type="boolean" not-null="true" /> <property name="Description" column="Description" type="string" not-null="true" /> <many-to-one name="Parent" column="ParentID"></many-to-one> <bag name="SubCategories" inverse="true"> <key column="ParentID"></key> <one-to-many class="Category"/> </bag> <set name="Products" table="Categories_Products"> <key column="CategoryId"></key> <many-to-many column="ProductId" class="Product"></many-to-many> </set> when I try to create the database I get the following error : failed: The INSERT statement conflicted with the FOREIGN KEY SAME TABLE constraint "FK9AD976763BF05E2A". The conflict occurred in database "CoderForTraders", table "dbo.Categories", column 'CategoryId'. The statement has been terminated. I looked on the net for some answers but found none. Thanks for your help

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• OneToOne JPA / Hibernate eager loading cause N+1 select

  - by Alexandre Lavoie

  I created a method to have multilingual text on different objects without creating field for each languages or tables for each objects types. Now the only problem I've got is N+1 select queries when doing a simple loading. Tables schema : CREATE TABLE `testentities` ( `keyTestEntity` int(11) NOT NULL, `keyMultilingualText` int(11) NOT NULL, PRIMARY KEY (`keyTestEntity`) ) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=utf8; CREATE TABLE `common_multilingualtexts` ( `keyMultilingualText` int(11) NOT NULL auto_increment, PRIMARY KEY (`keyMultilingualText`) ) ENGINE=MyISAM AUTO_INCREMENT=0 DEFAULT CHARSET=utf8; CREATE TABLE `common_multilingualtexts_values` ( `languageCode` varchar(5) NOT NULL, `keyMultilingualText` int(11) NOT NULL, `value` text, PRIMARY KEY (`languageCode`,`keyMultilingualText`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; MultilingualText.java @Entity @Table(name = "common_multilingualtexts") public class MultilingualText implements Serializable { private Integer m_iKeyMultilingualText; private Map<String, String> m_lValues = new HashMap<String, String>(); public void setKeyMultilingualText(Integer p_iKeyMultilingualText) { m_iKeyMultilingualText = p_iKeyMultilingualText; } @Id @GeneratedValue @Column(name = "keyMultilingualText") public Integer getKeyMultilingualText() { return m_iKeyMultilingualText; } public void setValues(Map<String, String> p_lValues) { m_lValues = p_lValues; } @ElementCollection(fetch = FetchType.EAGER) @CollectionTable(name = "common_multilingualtexts_values", joinColumns = @JoinColumn(name = "keyMultilingualText")) @MapKeyColumn(name = "languageCode") @Column(name = "value") public Map<String, String> getValues() { return m_lValues; } public void put(String p_sLanguageCode, String p_sValue) { m_lValues.put(p_sLanguageCode,p_sValue); } public String get(String p_sLanguageCode) { if(m_lValues.containsKey(p_sLanguageCode)) { return m_lValues.get(p_sLanguageCode); } return null; } } And it is used like this on a object (having a foreign key to the multilingual text) : @Entity @Table(name = "testentities") public class TestEntity implements Serializable { private Integer m_iKeyEntity; private MultilingualText m_oText; public void setKeyEntity(Integer p_iKeyEntity) { m_iKeyEntity = p_iKeyEntity; } @Id @GeneratedValue @Column(name = "keyEntity") public Integer getKeyEntity() { return m_iKeyEntity; } public void setText(MultilingualText p_oText) { m_oText = p_oText; } @OneToOne(cascade = CascadeType.ALL) @JoinColumn(name = "keyText") public MultilingualText getText() { return m_oText; } } Now, when doing a simple HQL query : from TestEntity, I get a query selecting TestEntity's and one query for each MultilingualText that need to be loaded on each TestEntity. I've searched a lot and found absolutely no solutions. I have tested : @Fetch(FetchType.JOIN) optional = false @ManyToOne instead of @OneToOne Now I am out of idea!

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• Any way to speed up this hierarchical query?

  - by RenderIn

  I've got a serious performance problem with a hierarchical query that I can't seem to fix. I am modeling several organization charts in my database, each representing a virtual organization within our company. For example, we have several temporary committees that are created from time to time and there may be a Committee Organizer role at the top of this virtual hierarchy, with several people assigned to the Committee Member role beneath the organizer. Some of our virtual organizations have many levels and several branches at each level. I have a single table in which I represent all the role assignments. i.e. a ROLE_ID column and a PARENT_ROLE_ID column which is a foreign key to the ROLE_ID column. For each assignment we also store as a column the location in the company where this person has the assignment. For example, the Committee Organizer would have a company-level/ CEO assignment, while the committee members would have department-level assignments such as ACCOUNTING, MARKETING, etc. So to model the organizer/member relationship for two individuals we would have: ROLE_ID = 4 PARENT_ROLE_ID = NULL EMPLOYEE_NUMBER = 213423 COMPANY_LOCATION = CEO ROLE_ID = 5 PARENT_ROLE_ID = 4 EMPLOYEE_NUMBER = 838221 COMPANY_LOCATION = ACCOUNTING Here's where things get tricky. I have an application that every person in the organization can log in to. When they log in they should be able to view all the virtual organizations in our company. e.g. the committee members should be able to see the committee organizer and vice-versa. However, only the committee organizer should be able to edit the committee members. The difficulty is in determining whether an individual (who can have multiple role assignments) has edit access for each other assignment. While this seems simple in the example, consider a virtual organization in which we have President at the top, 5 departments directly beneath him, 2 subdepartments below each department. We only want people in the Accounting department to be able to edit individuals in the subdepartments belonging to the Accounting department. They should not have edit access to anybody in the Marketing department or its subdepartments. To determine edit access when a user views a virtual organization in our company I run a query that executes two inline views: A) Hierarchically query for all assignments in this virtual organization and using SYS_CONNECT_BY_PATH to store the entire path to each user/role/company_location and B) Hierarchically retrieve all the assignments the individual logged in has and using the SYS_CONNECT_BY_PATH to store the entire path to each of these assignments. The result of the query is all the records from A) plus a boolean determined by joining with B) which flags whether the logged in user has edit access for each record. Indexes don't seem to be helping... it simply appears that there is too much processing going on to separate all the records and then determine edit access. One issue is that I can't store the SYS_CONNECT_BY_PATH and index it... determining whether an individual record has edit access consists of comparing if: test_record_sys_path LIKE individual_record_sys_path || '%' Is a materialized view the answer?

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• Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

  - by Erik Neu

  I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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• What is the best way to archive data in a relational database?

  - by GenericTypeTea

  I have a bit of an issue with a particular aspect of a program I'm working on. I need the ability to archive (fix) a table so that a change anywhere in the system will not affect the results it returns. This is the basic structure of what I need to fix: Recipe --> Recipe (as sub recipe) Recipe --> Ingredients So, if I fix a Recipe, I need to ensure all the sub recipes (including all the sub recipes sub recipes and so forth) are fixed and all its ingredients are fixed. The problem is that the sub recipe and ingredients still need to be modifiable as they are used by other recipes that are not fixed. I came up with a solution whereby I serialize (with protobuf-net) a master object that deals with the recipe and all the sub recipes and ingredients and save the archive data to a table like follows: Archive{ ReferenceId, (i.e. RecipeId) ReferenceTypeId, (i.e. Recipe) ArchiveData varbinary(max) } Now, this works great and is almost perfect... however I totally forgot (I'd love to blame the agile development mentally, however this was just short sighted) that this information needs to be reported on. As far as I'm aware I can't think how I could inflate the serialized data back into my Recipe Object and use it in a Report. I'm using the standard SQL 2005 report services at the moment. Alternatively, I guess I could do the following: Duplicate every table and tag the word "Archive" on the end of the table name. This would then give me an area of specific archive data... but ignoring my simplified example, there'd actually be about 15 tables duplicated. Add a nullable, non-foreign key property called "CopiedFromId" to every table that contains fixed data and duplicate every record that the recipe (and all it's sub recipes and all their sub recipes) touches. Create some sort of denormalised structure that could be restored from at a later date to the original, unfixed recipe. Although I think this would be like option 1 and involve a lot of extra tables. Anyway, I'm at a total loss and do not like any of the ideas particularly. Can anyone please advise the best course of action? EDIT: Or 4) Create tables specific to what the report requires and populate them with the data when the user clicks the report button? This would cause about 4 extra tables for the report in question.

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• CakePHP HABTM: Editing one item casuses HABTM row to get recreated, destroys extra data

  - by leo-the-manic

  I'm having trouble with my HABTM relationship in CakePHP. I have two models like so: Department HABTM Location. One large company has many buildings, and each building provides a limited number of services. Each building also has its own webpage, so in addition to the HABTM relationship itself, each HABTM row also has a url field where the user can visit to find additional information about the service they're interested and how it operates at the building they're interested in. I've set up the models like so: <?php class Location extends AppModel { var $name = 'Location'; var $hasAndBelongsToMany = array( 'Department' => array( 'with' => 'DepartmentsLocation', 'unique' => true ) ); } ?> <?php class Department extends AppModel { var $name = 'Department'; var $hasAndBelongsToMany = array( 'Location' => array( 'with' => 'DepartmentsLocation', 'unique' => true ) ); } ?> <?php class DepartmentsLocation extends AppModel { var $name = 'DepartmentsLocation'; var $belongsTo = array( 'Department', 'Location' ); // I'm pretty sure this method is unrelated. It's not being called when this error // occurs. Its purpose is to prevent having two HABTM rows with the same location // and department. function beforeSave() { // kill any existing rows with same associations $this->log(__FILE__ . ": killing existing HABTM rows", LOG_DEBUG); $result = $this->find('all', array("conditions" => array("location_id" => $this->data['DepartmentsLocation']['location_id'], "department_id" => $this->data['DepartmentsLocation']['department_id']))); foreach($result as $row) { $this->delete($row['DepartmentsLocation']['id']); } return true; } } ?> The controllers are completely uninteresting. The problem: If I edit the name of a Location, all of the DepartmentsLocations that were linked to that Location are re-created with empty URLs. Since the models specify that unique is true, this also causes all of the newer rows to overwrite the older rows, which essentially destroys all of the URLs. I would like to know two things: Can I stop this? If so, how? And, on a less technical and more whiney note: Why does this even happen? It seems bizarre to me that editing a field through Cake should cause so much trouble, when I can easily go through phpMyAdmin, edit the Location name there, and get exactly the result I would expect. Why does CakePHP touch the HABTM data when I'm just editing a field on a row? It's not even a foreign key!

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• Rails / ActiveRecord Modeling Help

  - by JM

  I’m trying to model a relationship in ActiveRecord and I think it’s a little beyond my skill level. Here’s the background. This is a horse racing project and I’m trying to model a horses Connections over time. Connections are defined as the Horse’s Current: Owner, Trainer and Jockey. Over time, a horse’s connections can change for a lot of different reasons: The owner sells the horse in a private sale The horse is claimed (purchase in a public sale) The Trainer switches jockeys The owner switches trainers In my first attempt at modeling this, I created the following tables: Horses, Owners, Trainers, Jockeys and Connections. Essentially, the Connections table was the has-many-through join table and was structured as follows: Connections Table 1 Id Horse_id Owner_id Trainer_id Jockey_id Status_Code Status_Date Change_Code The Horse, Owner, Trainer and Jockey foreign keys are self explanatory. The status code is 1 or 0 (1 active, 0 inactive) and the status date is the date the status changed. Change_code is and integer or string value that represent the reason for the change (private sale, claim, jockey change, etc) The key benefit of this approach is that the Connection is represented as one record in the connections table. The downside is that I have to have a table for Owner (1), Trainer (2) and Jockey (3) when one table could due. In my second attempt at modeling this I created the following tables: Horses, Connections, Entities The Entities tables has the following structure Entities Table id First_name Last_name Role where Role represents if the entity is a Owner, Trainer or Jockey. Under this approach, my Connections table has the following structure Connections Table 2 id Horse_id Entity_id Role Status_Code Status_Date Change_Code 1 1 1 1 1 1/1/2010 2 1 4 2 1 1/1/2010 3 1 10 3 1 1/1/2010 This approach has the benefit of eliminating two tables, but on the other hand the Connection is now comprised of three different records as opposed to one in the first approach. What believe I’m looking for is an approach that allows me to capture the Connection in one record, but also uses an Entities table with roles instead of the Owner, Trainer and Jockey tables. I’m new to ActiveRecord and rails so any and all input would be greatly appreciated. Perhaps there are other ways that would even be better. Thanks!

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• derby + hibernate ConstraintViolationException using manytomany relationships

  - by user364470

  Hi, I'm new to Hibernate+Derby... I've seen this issue mentioned throughout the google, but have not seen a proper resolution. This following code works fine with mysql, but when I try this on derby i get exceptions: ( each Tag has two sets of files and vise-versa - manytomany) Tags.java @Entity @Table(name="TAGS") public class Tags implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) public long getId() { return id; } @ManyToMany(targetEntity=Files.class ) @ForeignKey(name="USER_TAGS_FILES",inverseName="USER_FILES_TAGS") @JoinTable(name="USERTAGS_FILES", joinColumns=@JoinColumn(name="TAGS_ID"), inverseJoinColumns=@JoinColumn(name="FILES_ID")) public Set<data.Files> getUserFiles() { return userFiles; } @ManyToMany(mappedBy="autoTags", targetEntity=data.Files.class) public Set<data.Files> getAutoFiles() { return autoFiles; } Files.java @Entity @Table(name="FILES") public class Files implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) public long getId() { return id; } @ManyToMany(mappedBy="userFiles", targetEntity=data.Tags.class) public Set getUserTags() { return userTags; } @ManyToMany(targetEntity=Tags.class ) @ForeignKey(name="AUTO_FILES_TAGS",inverseName="AUTO_TAGS_FILES") @JoinTable(name="AUTOTAGS_FILES", joinColumns=@JoinColumn(name="FILES_ID"), inverseJoinColumns=@JoinColumn(name="TAGS_ID")) public Set getAutoTags() { return autoTags; } I add some data to the DB, but when running over Derby these exception turn up (the don't using mysql) Exceptions SEVERE: DELETE on table 'FILES' caused a violation of foreign key constraint 'USER_FILES_TAGS' for key (3). The statement has been rolled back. Jun 10, 2010 9:49:52 AM org.hibernate.event.def.AbstractFlushingEventListener performExecutions SEVERE: Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: could not delete: [data.Files#3] at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:2712) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:2895) at org.hibernate.action.EntityDeleteAction.execute(EntityDeleteAction.java:97) at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:268) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:260) at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:184) at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321) at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51) at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1206) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:613) at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:344) at $Proxy13.flush(Unknown Source) at data.HibernateORM.removeFile(HibernateORM.java:285) at data.DataImp.removeFile(DataImp.java:195) at booting.DemoBootForTestUntilTestClassesExist.main(DemoBootForTestUntilTestClassesExist.java:62) I have never used derby before so maybe there is something crutal that i'm missing 1) what am I doing wrong? 2) is there any way of cascading properly when I have 2 many-to-many relationships between two classes? Thanks!

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• Optimize date query for large child tables: GiST or GIN?

  - by Dave Jarvis

  Problem 72 child tables, each having a year index and a station index, are defined as follows: CREATE TABLE climate.measurement_12_013 ( -- Inherited from table climate.measurement_12_013: id bigint NOT NULL DEFAULT nextval('climate.measurement_id_seq'::regclass), -- Inherited from table climate.measurement_12_013: station_id integer NOT NULL, -- Inherited from table climate.measurement_12_013: taken date NOT NULL, -- Inherited from table climate.measurement_12_013: amount numeric(8,2) NOT NULL, -- Inherited from table climate.measurement_12_013: category_id smallint NOT NULL, -- Inherited from table climate.measurement_12_013: flag character varying(1) NOT NULL DEFAULT ' '::character varying, CONSTRAINT measurement_12_013_category_id_check CHECK (category_id = 7), CONSTRAINT measurement_12_013_taken_check CHECK (date_part('month'::text, taken)::integer = 12) ) INHERITS (climate.measurement) CREATE INDEX measurement_12_013_s_idx ON climate.measurement_12_013 USING btree (station_id); CREATE INDEX measurement_12_013_y_idx ON climate.measurement_12_013 USING btree (date_part('year'::text, taken)); (Foreign key constraints to be added later.) The following query runs abysmally slow due to a full table scan: SELECT count(1) AS measurements, avg(m.amount) AS amount FROM climate.measurement m WHERE m.station_id IN ( SELECT s.id FROM climate.station s, climate.city c WHERE -- For one city ... -- c.id = 5182 AND -- Where stations are within an elevation range ... -- s.elevation BETWEEN 0 AND 3000 AND 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 ) AND -- -- Begin extracting the data from the database. -- -- The data before 1900 is shaky; insufficient after 2009. -- extract( YEAR FROM m.taken ) BETWEEN 1900 AND 2009 AND -- Whittled down by category ... -- m.category_id = 1 AND m.taken BETWEEN -- Start date. (extract( YEAR FROM m.taken )||'-01-01')::date AND -- End date. Calculated by checking to see if the end date wraps -- into the next year. If it does, then add 1 to the current year. -- (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date GROUP BY extract( YEAR FROM m.taken ) The sluggishness comes from this part of the query: m.taken BETWEEN /* Start date. */ (extract( YEAR FROM m.taken )||'-01-01')::date AND /* End date. Calculated by checking to see if the end date wraps into the next year. If it does, then add 1 to the current year. */ (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date The HashAggregate from the plan shows a cost of 10006220141.11, which is, I suspect, on the astronomically huge side. There is a full table scan on the measurement table (itself having neither data nor indexes) being performed. The table aggregates 237 million rows from its child tables. Question What is the proper way to index the dates to avoid full table scans? Options I have considered: GIN GiST Rewrite the WHERE clause Separate year_taken, month_taken, and day_taken columns to the tables What are your thoughts? Thank you!

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• Should we denormalize database to improve performance?

  - by Groo

  We have a requirement to store 500 measurements per second, coming from several devices. Each measurement consists of a timestamp, a quantity type, and several vector values. Right now there is 8 vector values per measurement, and we may consider this number to be constant for needs of our prototype project. We are using HNibernate. Tests are done in SQLite (disk file db, not in-memory), but production will probably be MsSQL. Our Measurement entity class is the one that holds a single measurement, and looks like this: public class Measurement { public virtual Guid Id { get; private set; } public virtual Device Device { get; private set; } public virtual Timestamp Timestamp { get; private set; } public virtual IList<VectorValue> Vectors { get; private set; } } Vector values are stored in a separate table, so that each of them references its parent measurement through a foreign key. We have done a couple of things to ensure that generated SQL is (reasonably) efficient: we are using Guid.Comb for generating IDs, we are flushing around 500 items in a single transaction, ADO.Net batch size is set to 100 (I think SQLIte does not support batch updates? But it might be useful later). The problem Right now we can insert 150-200 measurements per second (which is not fast enough, although this is SQLite we are talking about). Looking at the generated SQL, we can see that in a single transaction we insert (as expected): 1 timestamp 1 measurement 8 vector values which means that we are actually doing 10x more single table inserts: 1500-2000 per second. If we placed everything (all 8 vector values and the timestamp) into the measurement table (adding 9 dedicated columns), it seems that we could increase our insert speed up to 10 times. Switching to SQL server will improve performance, but we would like to know if there might be a way to avoid unnecessary performance costs related to the way database is organized right now. [Edit] With in-memory SQLite I get around 350 items/sec (3500 single table inserts), which I believe is about as good as it gets with NHibernate (taking this post for reference: http://ayende.com/Blog/archive/2009/08/22/nhibernate-perf-tricks.aspx). But I might as well switch to SQL server and stop assuming things, right? I will update my post as soon as I test it.

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• With EJB 2.1, is declaring references to resources in ejb-jar.xml required?

  - by zwerd328

  I'm using Weblogic 9.2 with a lot of MDBs. These MDBs access JDBC DataSources and write to both locally and externally managed JMS Destinations using local and foreign XAConnectionFactorys, respectively. Each MDB demarcates a container-managed JTA transaction that should be distributed amongst all of these resources. Below is an excerpt from my ejb-jar.xml for an MDB that consumes from a local Queue called "MyDestination" and produces to an IBM Websphere MQ Queue called "MyOtherDestination". These logical names are linked to physical objects in my weblogic-ejb-jar.xml file. Is it required to use the <resource-ref> and <message-destination-ref> tags to expose the ConnectionFactory and Queue to the MDB? If so, is it required by Weblogic or is it required by the J2EE spec? And for what purpose? For example, is it required to support XA transactionality? I'm already aware of the benefit of decoupling the administered objects from my MDB using names exposed to the naming context of the MDB. Is this the only value added when specifying these tags? In other words, is it acceptable to just reference these objects from my MDB using the InitialContext and the objects' fully-qualified names? <enterprise-bean> <message-driven> <ejb-name>MyMDB</ejb-name> <ejb-class>com.mycompany.MyMessageDrivenBean</ejb-class> <transaction-type>Container</transaction-type> <message-destination-type>javax.jms.Queue</message-destination> <message-destination-link>MyDestination</message-destination-link> <resource-ref> <res-ref-name>jms/myQCF</res-ref-name> <res-type>javax.jms.XAConnectionFactory</res-type> <res-auth>Container</res-auth> </resource-ref> <message-destination-ref> <message-destination-ref-name>jms/myOtherDestination</message-destination-ref-name> <message-destination-type>javax.jms.Queue</message-destination-type> <message-destination-usage>Produces</message-destination-usage> <message-destination-link>MyOtherDestination</message-destination-link> </message-destination-ref> </message-driven> <enterprise-bean>

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