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• Large Product catalog with statistics - alternatives to Sql Server?

  - by Eric P

  I am building UI for a large product catalog (millions of products). I am using Sql Server, FreeText search and ASP.NET MVC. Tables are normalized and indexed. Most queries take less then a second to return. The issue is this. Let's say user does the search by keyword. On search results page I need to display/query for: First 20 matching products (paged, sorted) Total count of matching products for paging List of stores only of matching products List of brands only of matching products List of colors only of matching products Each query takes about .5 to 1 seconds. Altogether it is like 5 seconds. I would like to get the whole page to load under 1 second. There are several approaches: Optimize queries even more. I already spent a lot of time on this one, so not sure it can be pushed further. Load products first, then load the rest of the information using AJAX. More like a workaround. Will need to revise UI. Re-organize data to be more Report friendly. Already aggregated a lot of fields. I checked out several similar sites. For ex. zappos.com. Not only they display the same information as I would like in under 1 second, but they also include statistics (number of results in each category). The following is the search for keyword "white" http://www.zappos.com/white How do sites like zappos, amazon make their results, filters and stats appear almost instantly?

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• Grails - Where to store properties related to domains

  - by GalmWing

  This is something I have been struggling about for some time now. The thing is: I have many (20 or so) static arrays of values. I say static because that is how I'm actually storing them, as static arrays inside some domains. For example, if I have a list of known websites, I do: class Website { ... static websites = ["web1", "web2" ...] } But I do this just while developing, because I can easily change the arrays if needed, but what I'm going to do when the application is ready for deployment? In my project it is very probable that, at some point, these arrays of values change. I've been researching on that matter, one can store application properties inside an external .properties file, but it will be impossible to store an array, even futile, because if some array gets an additional value, the application can't recognize it until the name of the new property is added where needed. Another approach is to store this information in the database, but for some reason it seems like a waste to add 20 or more tables that will have just two rows, an id and a name. And the last option, as far as I know, would be an XML, but I'm not very experienced with those. It seems groovy has a way of creating and reading XML files relatively easy, but I don't know how difficult would be to modify an XML whose layout is predefined in the application. Needless to say that storing them in the config.groovy is not an option since any change will require to recompile. I haven't come across some "standard" (maybe a best practice?) way of dealing with these. So the questions is: Where to store these arrays?

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• performance issue: difference between select s.* vs select *

  - by kamil

  Recently I had some problem in performance of my query. The thing is described here: poor Hibernate select performance comparing to running directly - how debug? After long time of struggling, I've finally discovered that the query with select prefix like: select sth.* from Something as sth... Is 300x times slower then query started this way: select * from Something as sth.. Could somebody help me, and asnwer why is that so? Some external documents on this would be really useful. The table used for testing was: SALES_UNIT table contains some basic info abot sales unit node such as name and etc. The only association is to table SALES_UNIT_TYPE, as ManyToOne. The primary key is ID and field VALID_FROM_DTTM which is date. SALES_UNIT_RELATION contains relation PARENT-CHILD between sales unit nodes. Consists of SALES_UNIT_PARENT_ID, SALES_UNIT_CHILD_ID and VALID_TO_DTTM/VALID_FROM_DTTM. No association with any tables. The PK here is ..PARENT_ID, ..CHILD_ID and VALID_FROM_DTTM The actual query I've done was: select s.* from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null select * from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null Same query, both uses left join and only difference is with select.

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• How do I execute queries upon DB connection in Rails?

  - by sycobuny

  I have certain initializing functions that I use to set up audit logging on the DB server side (ie, not rails) in PostgreSQL. At least one has to be issued (setting the current user) before inserting data into or updating any of the audited tables, or else the whole query will fail spectacularly. I can easily call these every time before running any save operation in the code, but DRY makes me think I should have the code repeated in as few places as possible, particularly since this diverges greatly from the ideal of database agnosticism. Currently I'm attempting to override ActiveRecord::Base.establish_connection in an initializer to set it up so that the queries are run as soon as I connect automatically, but it doesn't behave as I expect it to. Here is the code in the initializer: class ActiveRecord::Base # extend the class methods, not the instance methods class << self alias :old_establish_connection :establish_connection # hide the default def establish_connection(*args) ret = old_establish_connection(*args) # call the default # set up necessary session variables for audit logging # call these after calling default, to make sure conn is established 1st db = self.class.connection db.execute("SELECT SV.set('current_user', 'test@localhost')") db.execute("SELECT SV.set('audit_notes', NULL)") # end "empty variable" err ret # return the default's original value end end end puts "Loaded custom establish_connection into ActiveRecord::Base" sycobuny:~/rails$ ruby script/server = Booting WEBrick = Rails 2.3.5 application starting on http://0.0.0.0:3000 Loaded custom establish_connection into ActiveRecord::Base This doesn't give me any errors, and unfortunately I can't check what the method looks like internally (I was using ActiveRecord::Base.method(:establish_connection), but apparently that creates a new Method object each time it's called, which is seemingly worthless cause I can't check object_id for any worthwhile information and I also can't reverse the compilation). However, the code never seems to get called, because any attempt to run a save or an update on a database object fails as I predicted earlier. If this isn't a proper way to execute code immediately on connection to the database, then what is?

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• Can a Snapshot transaction fail and only partially commit in a TransactionScope?

  - by Travis Brooks

  Greetings I stumbled onto a problem today that seems sort of impossible to me, but its happening...I'm calling some database code in c# that looks something like this: using(var tran = MyDataLayer.Transaction()) { MyDataLayer.ExecSproc(new SprocTheFirst(arg1, arg2)); MyDataLayer.CallSomethingThatEventuallyDoesLinqToSql(arg1, argEtc); tran.Commit(); } I've simplified this a bit for posting, but whats going on is MyDataLayer.Transaction() makes a TransactionScope with the IsolationLevel set to Snapshot and TransactionScopeOption set to Required. This code gets called hundreds of times a day, and almost always works perfectly. However after reviewing some data I discovered there are a handful of records created by "SprocTheFirst" but no corresponding data from "CallSomethingThatEventuallyDoesLinqToSql". The only way that records should exist in the tables I'm looking at is from SprocTheFirst, and its only ever called in this one function, so if its called and succeeded then I would expect CallSomethingThatEventuallyDoesLinqToSql would get called and succeed because its all in the same TransactionScope. Its theoretically possible that some other dev mucked around in the DB, but I don't think they have. We also log all exceptions, and I can find nothing unusual happening around the time that the records from SprocTheFirst were created. So, is it possible that a transaction, or more properly a declarative TransactionScope, with Snapshot isolation level can fail somehow and only partially commit?

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• How to close and open access to SQL Server 2008 in Windows application?

  - by hgulyan

  Hi, I have a MS Access 97 application (but the question is general) working directly with SQL Server 2008 (without application server or anything). Numbers of users can be up to 1000. Windows Authentication is used. The question is: How to handle modes, so some users will be allowed to work in read-only mode some users won't have access to db for some time My versions: Using a table with a mode id for every group of users, that will work the same way. On Form Load application will query that table for mode id. Using trigger on the tables, that must work according to that mode. The trigger will query mode value and doesn't work if access is closed or it's in read-only mode I know these are not the best solutions, that's why I'm asking for your advice. There's one more point. If the mode is changed to "access-is-closed" for a group of users, that group must not be able to query to DB starting that moment. With first solution I wrote it won't work, because user can be in application at that moment and no form load event will work. How can I do this? Is there any optimal solution? Thank you. Any help would be appreciated.

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• Mixing together Connect by, inner join and sum with Oracle

  - by François

  Hey there, I need help with a oracle query. Excuse me in advance for my english. Here is my setup: I have 2 tables called respectively "tasks" and "timesheets". The "tasks" table is a recursive one, that way each task can have multiple subtasks. Each timesheet is associated with a task (not necessarily the "root" task) and contains the number of hours worked on it. Example: Tasks id:1 | name: Task A | parent_id: NULL id:2 | name: Task A1 | parent_id: 1 id:3 | name: Task A1.1 | parent_id: 2 id:4 | name: Task B | parent_id: NULL id:5 | name: Task B1 | parent_id: 4 Timesheets id:1 | task_id: 1 | hours: 1 id:2 | task_id: 2 | hours: 3 id:3 | task_id:3 | hours: 1 id:5 | task_id:5 | hours:1 ... What I want to do: I want a query that will return the sum of all the hours worked on a "task hierarchy". If we take a look at the previous example, It means I would like to have the following results: task A - 5 hour(s) | task B - 1 hour(s) At first I tried this SELECT TaskName, Sum(Hours) "TotalHours" FROM ( SELECT replace(sys_connect_by_path(decode(level, 1, t.name), '~'), '~') As TaskName, ts.hours as hours FROM tasks t INNER JOIN timesheets ts ON t.id=ts.task_id START WITH PARENTOID=-1 CONNECT BY PRIOR t.id = t.parent_id ) GROUP BY TaskName Having Sum(Hours) > 0 ORDER BY TaskName And it almost work. THe only problem is that if there are no timesheet for a root task, it will skip the whole hieararchy... but there might be timesheets for the child rows and it is exactly what happens with Task B1. I know it is the "inner join" part that is causing my problem but I'm not sure how can I get rid of it. Any idea how to solve this problem? Thank you

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• LINQ to SQL - database relationships won't update after submit

  - by Quantic Programming

  I have a Database with the tables Users and Uploads. The important columns are: Users -> UserID Uploads -> UploadID, UserID The primary key in the relationship is Users -> UserID and the foreign key is Uploads -> UserID. In LINQ to SQL, I do the following operations: Retrieve files var upload = new Upload(); upload.UserID = user.UserID; upload.UploadID = XXX; db.Uploads.InsertOnSubmit(upload) db.SubmitChanges(); If I do that and rerun the application (and the db object is re-built, of course) - if do something like this: foreach(var upload in user.Uploads) I get all the uploads with that user's ID. (like added in the previous example) The problem is, that my application, after adding an upload an submitting changes, doesn't update the user.Uploads collection. i.e - I don't get the newly added uploads. The user object is stored in the Session object. At first, I though that the LINQ to SQL Framework doesn't update the reference of the object, therefore I should simply "reset" the user object from a new SQL request. I mean this: Session["user"] = db.Users.Where(u => u.UserID == user.UserID).SingleOrDefault(); (Where user is the previous user) But it didn't help. Please note: After rerunning the application, user.Uploads does have the new upload! Did anyone experience this type of problem, or is it normal behavior? I am a newbie to this framework. I would gladly take any advice. Thank you!

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• Java: over-typed structures?

  - by HH

  Term over-type structure = a data structure that accepts different types, can be primitive or user-defined. I think ruby supports many types in structures such as tables. I tried a table with types 'String', 'char' and 'File' in Java but errs. How can I have over-typed structure in Java? How to show types in declaration? What about in initilization? Suppose a structure: INDEX VAR FILETYPE //0 -> file FILE //1 -> lineMap SizeSequence //2 -> type char //3 -> binary boolean //4 -> name String //5 -> path String Code import java.io.*; import java.util.*; public class Object { public static void print(char a) { System.out.println(a); } public static void print(String s) { System.out.println(s); } public static void main(String[] args) { Object[] d = new Object[6]; d[0] = new File("."); d[2] = 'T'; d[4] = "."; print(d[2]); print(d[4]); } } Errors Object.java:18: incompatible types found : java.io.File required: Object d[0] = new File("."); ^ Object.java:19: incompatible types found : char required: Object d[2] = 'T'; ^

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• Why does the WCF 3.5 REST Starter Kit do this?

  - by Brandon

  I am setting up a REST endpoint that looks like the following: [WebInvoke(Method = "POST", UriTemplate = "?format=json", BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json)] and [WebInvoke(Method = "DELETE", UriTemplate = "?token={token}&format=json", ResponseFormat = WebMessageFormat.Json)] The above throws the following error: UriTemplateTable does not support '?format=json' and '?token={token}&format=json' since they are not equivalent, but cannot be disambiguated because they have equivalent paths and the same common literal values for the query string. See the documentation for UriTemplateTable for more detail. I am not an expert at WCF, but I would imagine that it should map first by the HTTP Method and then by the URI Template. It appears to be backwards. If both of my URI templates are: ?token={token}&format=json This works because they are equivalent and it then appears to look at the HTTP Method where one is POST and the other is DELETE. Is REST supposed to work this way? Why are the URI Template Tables not being sorted first by HTTP Method and then by URI Template? This can cause some serious frustrations when 1 HTTP Method requires a parameter and another does not, or if I want to do optional parameters (e.g. if the 'format' parameter is not passed, default to XML).

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• Too many columns to index - use mySQL Partitions?

  - by Christopher Padfield

  We have an application with a table with 20+ columns that are all searchable. Building indexes for all these columns would make write queries very slow; and any really useful index would often have to be across multiple columns increasing the number of indexes needed. However, for 95% of these searches, only a small subset of those rows need to be searched upon, and quite a small number - say 50,000 rows. So, we have considered using mySQL Partition tables - having a column that is basically isActive which is what we divide the two partitions by. Most search queries would be run with isActive=1. Most queries would then be run against the small 50,000 row partition and be quick without other indexes. Only issue is the rows where isActive=1 is not fixed; i.e. it's not based on the date of the row or anything fixed like that; we will need to update isActive based on use of the data in that row. As I understand it that is no problem though; the data would just be moved from one partition to another during the UPDATE query. We do have a PK on id for the row though; and I am not sure if this is a problem; the manual seemed to suggest the partition had to be based on any primary keys. This would be a huge problem for us because the primary key ID has no basis on whether the row isActive.

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• How can I improve this SQL to avoid several problems with its results?

  - by Josh Curren

  I am having some problems with trying to search. Currently this will only return results that have at least 1 row in the maintenance_parts table. I would like it to return results even if there are 0 parts rows. My second problem is that when you search for a vehicle and it should return multiple results (multiple maintenance rows) it will only return 1 result for that vehicle. Some Background Info: The user has 2 fields to fill out. The fields are vehicle and keywords. The vehicle field is meant to allow searching based on the make, model, VIN, truck number (often is 2 - 3 digits or a letter prefix followed by 2 digits), and a few other fields that belong to the truck table. The keywords are meant to search most fields in the maintenance and maintenance_parts tables (things like the description of the work, parts name, parts number). The maintenance_parts table can contain 0, 1, or more rows for each maintenance row. The truck table contains exactly 1 row for every maintenance row. A truck can have multiple maintenance records. "SELECT M.maintenance_id, M.some_id, M.type_code, M.service_date, M.mileage, M.mg_id, M.mg_type, M.comments, M.work_done, MATCH( M.comments, M.work_done) AGAINST( '$keywords' ) + MATCH( P.part_num, P.part_desc, P.part_ref) AGAINST( '$keywords' ) + MATCH( T.truck_number, T.make, T.model, T.engine, T.vin_number, T.transmission_number, T.comments) AGAINST( '$vehicle' ) AS score FROM maintenance M, maintenance_parts P, truck T WHERE M.maintenance_id = P.maintenance_id AND M.some_id = T.truck_id AND M.type_code = 'truck' AND ( (MATCH( T.truck_number, T.make, T.model, T.engine, T.vin_number, T.transmission_number, T.comments) AGAINST( '$vehicle' ) OR T.truck_number LIKE '%$vehicle%') OR MATCH( P.part_num, P.part_desc, P.part_ref) AGAINST( '$keywords' ) OR MATCH( M.comments, M.work_done) AGAINST( '$keywords' ) ) AND M.status = 'A' GROUP BY maintenance_id ORDER BY score DESC, maintenance_id DESC LIMIT 0, $limit"

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• How to configure a NSPopupButton for displaying multiple values in a TableView?

  - by jekmac

  Hi there! I'm using two entities A and B with to-many-to-many relationship. Lets say I got an entity A with attribute aAttrib and a to-many relationship aRelat to another entity B with attribute bAttrib and a to-many relationship bRelat with entity A. Now I am building an interface with two tables one for entity A and another for entity B. The table for entity B has two columns one for bAttrib and one for the relationship aRelat. The aRelat-column should be a NSPopupButtonCell to display multiple aAttrib values. I'd like to set all the bindings in InterfaceBuilder in Table Column Bindings: -- I have two NSArrayController each for one entity: Object Controller Mode:Entity Array Controller Bindings: Parameters Managed Object Context bind to File's Owner -- One Table Cloumn with a PopUpButtonCell: TableCloumnBindings Content bind to Entity A with ControllerKey arrangedObjects; Content Values bind to Entity A with ModelKeyPath aAttrib Selected Object bind to Entity B with ModelKeyPath bRelat I know that this configuration doesn't allow multiple value setting. But I don't know how to do the right one. Getting the following message: HIToolbox: ignoring exception 'Unacceptable type of value for to-many relationship: property = "bRelat"; desired type = NSSet; given type = NSCFString; value = testValue.' that raised inside Carbon event dispatch... Does anyone have any idea?

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• Kohana Auth Library Deployment

  - by Steve

  My Kohana app runs perfectly on my local machine. When I deployed my app to a server (and adjust the config files appropriately), I can no longer log into the app. I've traced through the app login routine on both my local version and the server version and they both agree with each other all the way through until you get to the auth.php controller logged_in() routine where suddenly, at line 140 - the is_object($this-user) test - the $user object no longer exists!?!?!? The login() function call that calls the logged_in() function successfully passes the following test, which causes a redirect to the logged_in() function. if(Auth::instance()->login($user, $post['password'])) Yes, the password and hash, etc all work perfectly. Here is the offending code: public function logged_in() { if ( ! is_object($this->user)) { // No user is currently logged in url::redirect('auth/login'); } etc... } As the code is the same between my local installation and the server, I reckon it must be some server setting that is messing with me. FYI: All the rest of the code works because I have a temporary backdoor available that allows me to use the application (view pages of tables, etc) without being logged in. Any ideas?

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• Multiple ID's in database

  - by eric

  I have a database that contains a few tables such as person, staff, member, and supporter. The person table contains information about every staff, member, and supporter. The information it contains is name,address,email, and telephone. I also created an id that is the primary key. My issue is that I also have an primary key ID for staff, member, and supporter. For instance, in the person table is John with id 1. He is a supporter so in the supporter table is pID(for person id)to reference back to John with all his information and ID(for supporter ID). pID references to the person table and every person has an ID incremented by 1 starting at 1. supporter ID is for every supporter and also starts at 1 and is incremented by 1. Is it possible to have in the supporter table pID = 1 and supporter ID = 1? Another person may have a pID = 26 and supporter ID = 5. Or will supporter ID have to be different than the pID and be something like "sup"? So you would have pID = 1 and supporter ID = sup1 or pID = 26 and supporter ID = sup5

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• Suggestion on Database structure for relational data

  - by miccet

  Hi there. I've been wrestling with this problem for quite a while now and the automatic mails with 'Slow Query' warnings are still popping in. Basically, I have Blogs with a corresponding table as well as a table that keeps track of how many times each Blog has been viewed. This last table has a huge amount of records since this page is relatively high traffic and it logs every hit as an individual row. I have tried with indexes on the fields that are included in the WHERE clause, but it doesn't seem to help. I have also tried to clean the table each week by removing old ( 1.weeks) records. SO, I'm asking you guys, how would you solve this? The query that I know is causing the slowness is generated by Rails and looks like this: SELECT count(*) AS count_all FROM blog_views WHERE (created_at >= '2010-01-01 00:00:01' AND blog_id = 1); The tables have the following structures: CREATE TABLE IF NOT EXISTS 'blogs' ( 'id' int(11) NOT NULL auto_increment, 'name' varchar(255) default NULL, 'perma_name' varchar(255) default NULL, 'author_id' int(11) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, 'blog_picture_id' int(11) default NULL, 'blog_picture2_id' int(11) default NULL, 'page_id' int(11) default NULL, 'blog_picture3_id' int(11) default NULL, 'active' tinyint(1) default '1', PRIMARY KEY ('id'), KEY 'index_blogs_on_author_id' ('author_id') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ; And CREATE TABLE IF NOT EXISTS 'blog_views' ( 'id' int(11) NOT NULL auto_increment, 'blog_id' int(11) default NULL, 'ip' varchar(255) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, PRIMARY KEY ('id'), KEY 'index_blog_views_on_blog_id' ('blog_id'), KEY 'created_at' ('created_at') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

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• .net printing multiple reports in one document (architecture question)

  - by LawsonM

  I understand how to print a single document via the PrintDocument class. However, I want to print multiple reports in one document. Each "report" will consist of charts, tables, etc. I want to have two reports per page. I've studied the few examples I can find on how to combine multiple documents into one; however, they always seem to work by creating a collection of objects (e.g. customer or order) that are then iterated over and drawn in the OnPrintPage method. My problem and hence the "architecture" question is that I don't want to cache the objects required to produce the report since they are very large and memory intensive. I'd simply like the resulting "report". One thought I had was to print the report to a metafile, cache that instead in a "MultiplePrintDocument" class and then position those images appropriately two to a page in the OnPrintPage method. I think this would be a lot more efficient and scalable in my case. But I'm not a professional programmer and can't figure out if I'm barking up the wrong tree here. I think the Graphics.BeginContainer and Graphics.Save methods might be relevant, but can't figure out how to implement or if there is a better way. Any pointers would be greatly appreciated.

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• SQL Duplicates Issue

  - by jeff

  I have two tables : Product and ProductRateDetail. The parent table is Product. I have duplicate records in the product table which need to be unique. There are entries in the ProductRateDetail table which correspond to duplicate records in the product table. Somehow I need to update the ProductRateDetail table to match the original (older) ID from the Product table and then remove the duplicates from the product table. I would do this manually but there are 100's of records. I.e. something like UPDATE tbl_productRateDetail SET productID = (originalID from tbl_product) then something like DELETE from tbl_product WHERE duplicate ID and only delete the recently added ID data example: (sorry can't work out this formatting thing) select * from dbo.Product where ProductCode = '10003' tbl_product ProductID ProductTypeID ProductDescription ProductCode ProductSize 365 1 BEND DOUBLE FLANGED 10003 80mmX90deg 1354 1 BEND DOUBLE FLANGED 10003 80mmX90deg SELECT * FROM [MSTS2].[dbo].[ProductRateDetail] WHERE ProductID in (365,1354) tbl_productratedetail ProductRateDetailID ProductRateID ProductID UnitRate 365 1 365 16.87 1032 5 365 16.87 2187 10 365 16.87 2689 11 365 16.87 3191 12 365 16.87 7354 21 1354 21.30 7917 22 1354 21.30 8480 23 1354 21.30 9328 25 1354 21.30 9890 26 1354 21.30 10452 27 1354 21.30 Please help!

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• SELECT product from subclass: How many queries do I need?

  - by Stefano

  I am building a database similar to the one described here where I have products of different type, each type with its own attributes. I report a short version for convenience product_type ============ product_type_id INT product_type_name VARCHAR product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id ... (common attributes to all product) magazine ======== magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id ... (magazine-specific attributes) web_site ======== web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id ... (web-site specific attributes) This way I do not need to make a huge table with a column for each attribute of different product types (most of which will then be NULL) How do I SELECT a product by product.product_id and see all its attributes? Do I have to make a query first to know what type of product I am dealing with and then, through some logic, make another query to JOIN the right tables? Or is there a way to join everything together? (if, when I retrieve the information about a product_id there are a lot of NULL, it would be fine at this point). Thank you

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• Is it possible to load an entire SQL Server CE database into RAM?

  - by DanM

  I'm using LinqToSql to query a small SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table via a foreign key, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of the appeal of LinqToSql. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view.

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• mailing system DB structure, need help

  - by Anna

  i have a system there user(sender) can write a note to friends(receivers), number of receivers=0. Text of the message is saved in DB and visible to sender and all receivers then they login to system. Sender can add more receivers at any time. More over any of receivers can edit the message and even remove it from DB. For this system i created 3 tables, shortly: users(userID, username, password) messages(messageID, text) list(id, senderID, receiverID, messageID) in table "list" each row corresponds to pair sender-receiver, like sender_x_ID -- receiver_1_ID -- message_1_ID sender_x_ID -- receiver_2_ID -- message_1_ID sender_x_ID -- receiver_3_ID -- message_1_ID Now the problem is: 1. if user deletes the message from table "messages" how to automatically delete all rows from table "list" which correspond to deleted message. Do i have to include some foreign keys? More important: 2. if sender has let say 3 receivers for his message1 (username1, username2 and username3) and at certain moment decides to add username4 and username5 and at the same time exclude username1 from the list of receivers. PHP code will get the new list of receivers (username2, username3, username4, username5) That means insert to table "list" sender_x_ID -- receiver_4_ID -- message_1_ID sender_x_ID -- receiver_5_ID -- message_1_ID and also delete from table "list" the row corresponding to user1 (which is not in the list or receivers any more) sender_x_ID -- receiver_1_ID -- message_1_ID which sql query to send from PHP to make it in an easy and intelligent way? Please help! Examples of sql queries would be perfect!

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• How would I associate a "Note" class to 4+ classes without creating lookup table for each associatio

  - by Gthompson83

  Im creating a project tasklist application. I have project, section, task, issue classes, and would like to use one class to be able to add simple notes to any object instance of those classes. The task, issue tables both use a standard identity field as a primary key. The section table has a two field primary key. The project table has a single int primary key defined by the user. Is there a way to associate the note class with each of these without using a seperate lookup table for each class? I'm not so sure my original idea is a decent way to implement this. I considered the following (each variable mapping to a field n the notes table. Private _NoteId As Integer Private _ProjectId As Integer Private _SectionId As Integer Private _SectionId2 As Integer Private _TaskId As Integer Private _IssueId As Integer Private _Note As String Private _UserId As Guid Then I would be able to write seperate methods (getProjectNotes, getTaskNotes) to get notes attached to each class. I started writing this a few weeks ago but got pulled away before i could finish. When revisiting this code today my first thought "this is retarded". Thoughts on drawbacks to this design?

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• data ownership and performance

  - by Ami

  We're designing a new application and we ran into some architectural question when thinking about data ownership. we broke down the system into components, for example Customer and Order. each of this component/module is responsible for a specific business domain, i.e. Customer deals with CRUD of customers and business process centered around customers (Register a n new customer, block customer account, etc.). each module is the owner of a set of database tables, and only that module may access them. if another module needs data that is owned by another module, it retrieves it by requesting it from that module. so far so good, the question is how to deal with scenarios such as a report that needs to show all the customers and for each customer all his orders? in such a case we need to get all the customers from the Customer module, iterate over them and for each one get all the data from the Order module. performance won't be good...obviously it would be much better to have a stored proc join customers table and orders table, but that would also mean direct access to the data that is owned by another module, creating coupling and dependencies that we wish to avoid. this is a simplified example, we're dealing with an enterprise application with a lot of business entities and relationships, and my goal is to keep it clean and as loosely coupled as possible. I foresee in the future many changes to the data scheme, and possibly splitting the system into several completely separate systems. I wish to have a design that would allow this to be done in a relatively easy way. Thanks!

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• Subquery with multiple results combined into a single field?

  - by Todd

  Assume I have these tables, from which i need to display search results in a browser: Table: Containers id | name 1 Big Box 2 Grocery Bag 3 Envelope 4 Zip Lock Table: Sale id | date | containerid 1 20100101 1 2 20100102 2 3 20091201 3 4 20091115 4 Table: Items id | name | saleid 1 Barbie Doll 1 2 Coin 3 3 Pop-Top 4 4 Barbie Doll 2 5 Coin 4 I need output that looks like this: itemid itemname saleids saledates containerids containertypes 1 Barbie Doll 1,2 20100101,20100102 1,2 Big Box, Grocery Bag 2 Coin 3,4 20091201,20091115 3,4 Envelope, Zip Lock 3 Pop-Top 4 20091115 4 Zip Lock The important part is that each item type only gets one record/row in the return on the screen. I accomplished this in the past by returning multiple rows of the same item and using a scripting language to limit the output. However, this makes the ui overly complicated and loopy. So, I'm hoping I can get the database to spit out only as many records as there are rows to display. This example may be a bit extreme because of the 2 joins needed to get to the container from the item (through the sale table). I'd be happy for just an example query that outputs this: itemid itemname saleids saledates 1 Barbie Doll 1,2 20100101,20100102 2 Coin 3,4 20091201,20091115 3 Pop-Top 4 20091115 I can only return a single result in a subquery, so I'm not sure how to do this.

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• Does this query fetch unnecessary information? Should I change the query?

  - by Camran

  I have this classifieds website, and I have about 7 tables in MySql where all data is stored. I have one main table, called "classifieds". In the classifieds table, there is a column called classified_id. This is not the PK, or a key whatsoever. It is just a number which is used for me to JOIN table records together. Ex: classifieds table: fordon table: id => 33 id => 12 classified_id => 10 classified_id => 10 ad_id => 'bmw_m3_92923' This above is linked together by the classified_id column. Now to the Q, I use this method to fetch all records WHERE the column ad_id matches any of the values inside an array, called in this case $ad_arr: SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*, hem_inredning.*, hobby.* FROM classified mt LEFT JOIN fordon ON fordon.classified_id = mt.classified_id LEFT JOIN boende ON boende.classified_id = mt.classified_id LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id LEFT JOIN business ON business.classified_id = mt.classified_id LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id LEFT JOIN hobby ON hobby.classified_id = mt.classified_id WHERE mt.ad_id IN ('$ad_arr')"; Is this good or would this actually fetch unnecessary information? Check out this Q I posted couple of days ago. In the comments HLGEM is commenting that it is wrong etc etc. What do you think? http://stackoverflow.com/questions/2782275/another-rookie-question-how-to-implement-count-here Thanks

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