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  • PHP forking and mysql database connection problem

    - by user298819
    I am now trying to do forking in php. I would like to do some query and update in child process.. the problem is that whenever a child process finish, it close the connection which makes the other queries fail. The following is my sample code!! #!/usr/local/bin/php <?php set_time_limit(0); # forever program! $db = mysql_connect("server","user","pwd"); mysql_select_db("schema",$db); $sql = "query"; $res = mysql_query($sql,$db); while($rows = mysql_fetch_array($res)) { $rv = pcntl_fork(); if($rv == -1){ echo "forking failed"; }elseif($rv){ echo "parent process $rv\n"; $db = mysql_connect("192.168.8.112","zwmuser","zwmuser",true); mysql_select_db("schema",$db); }else{ echo "child process $rv\n"; $sql1 = "another query"; $res1 = mysql_query($sql1,$db); while($messages = mysql_fetch_array($res1)) { $sql2 = "update query"; mysql_query($sql2,$db); } exit(0); //it terminates both child process and mysql connection! } } ?>

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  • Binding DataGridComboBoxColumn to a one to many entity framework relation

    - by Cristian
    I have two tables in the model, one table contains entries related to the other table in a one to many relations, for example: Table User ID Name Table Comments ID UserID Title Text I want to show a datagrid in a WPF window with two columns, one text column with the User name and another column with a combobox showing all the comments made by the user. The datagrid definition is like this: <DataGrid AutoGenerateColumns="False" [layout options...] Name="dataGrid1" ItemsSource="{Binding}"> <DataGrid.Columns> <DataGridTextColumn Header="Name" Binding="{Binding Path=Name}"/> <DataGridComboBoxColumn Header="Comments" SelectedValueBinding="{Binding Path=UserID}" SelectedValuePath="ID" DisplayMemberPath="Title" ItemsSource="{Binding Path=Comments}" /> </DataGrid.Columns> </DataGrid> in the code I assign the DataContext like this: dataGrid1.DataContext = entities.Users; The entity User has a property named Comments that leads to all the comments made by the user. The queries are returning data and the user names are shown but the combobox is not being filled. May be the approach is totally wrong or I'm just missing a very simple point here, I'm opened to learn better methods to do this. Thanks

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  • Is there something like a "long running offline transaction" for NHibernate or any other ORM?

    - by Vilx-
    In essence this is a followup of this question. I'm beginning to feel that I should give up the whole idea, but I'll give it one more shot. What I want is pretty much like a DB transaction. It should track my changes to the DB and then in the end allow me to either commit or rollback them. If I insert an object, I should get it back in my next (appropriate) SELECT query. If I delete it, future SELECT queries should not return it. Etc. But there is one catch - this transaction would be very long running. It would start when the user opened a form (I'm talking about Windows Forms here), and the commit/rollback would be when the user closed it(with OK/Cancel). So it could take anywhere between seconds and days. This requirement rules out a standard DB transaction because that would lock the tables/rows it touched, and other users wouldn't be able to use the system. Also the transaction should not commit ANY changes to the DB until it was really committed. So if one user makes some changes, others don't see them until OK button is hit. This prevents errors in case the computer crashes or is disconnected from the network. I'm quite OK if the solution puts constraints on my model (I'm using MSSQL 2008, btw). I can design the DB/code any way I like. I'm also fine with the idea that a commit could fail because someone already modified one of the objects my transaction touched. Is there anything like this? I looked at NHibernate.Burrow, but I'm not sure that that's the thing I want. Added: It's the very beginning of the project so I'm not tied to NHibernate. I started out with it but I can still change easily.

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  • Database warehouse design: fact tables and dimension tables

    - by morpheous
    I am building a poor man's data warehouse using a RDBMS. I have identified the key 'attributes' to be recorded as: sex (true/false) demographic classification (A, B, C etc) place of birth date of birth weight (recorded daily): The fact that is being recorded My requirements are to be able to run 'OLAP' queries that allow me to: 'slice and dice' 'drill up/down' the data and generally, be able to view the data from different perspectives After reading up on this topic area, the general consensus seems to be that this is best implemented using dimension tables rather than normalized tables. Assuming that this assertion is true (i.e. the solution is best implemented using fact and dimension tables), I would like to seek some help in the design of these tables. 'Natural' (or obvious) dimensions are: Date dimension Geographical location Which have hierarchical attributes. However, I am struggling with how to model the following fields: sex (true/false) demographic classification (A, B, C etc) The reason I am struggling with these fields is that: They have no obvious hierarchical attributes which will aid aggregation (AFAIA) - which suggest they should be in a fact table They are mostly static or very rarely change - which suggests they should be in a dimension table. Maybe the heuristic I am using above is too crude? I will give some examples on the type of analysis I would like to carryout on the data warehouse - hopefully that will clarify things further. I would like to aggregate and analyze the data by sex and demographic classification - e.g. answer questions like: How does male and female weights compare across different demographic classifications? Which demographic classification (male AND female), show the most increase in weight this quarter. etc. Can anyone clarify whether sex and demographic classification are part of the fact table, or whether they are (as I suspect) dimension tables.? Also assuming they are dimension tables, could someone elaborate on the table structures (i.e. the fields)? The 'obvious' schema: CREATE TABLE sex_type (is_male int); CREATE TABLE demographic_category (id int, name varchar(4)); may not be the correct one.

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  • Create ABPerson Records in a Shared CardDAV (10.6/Server Hosted) AddressBook

    - by Woodster
    Hello, My app presently reads and writes to the local Mac OS X 10.6 client addressbook using the AddressBook.framework. It works fine. 10.6 Server introduced AddressBook Server, which 10.6 clients can connect to by setting up a CardDAV Account. User and Group records can be stored in that account, which is synchronized to the 10.6 server and made available to other clients who access the same CardDAV account. Mail.app is able to autocomplete the email addresses from accounts that are in the local datastore as well as the remote CardDAV datastore. ABPeoplePicker can see both. But, programatically, I'm not getting any CardDAV-based data returned from my queries against the shared AddressBook. I'm not sure if I need to ask it for a different AddressBook, or if I need to modify my fetch-request to indicate that I want it to be able to use the shared data too. My goal is to adapt the current code so that it can read/write to the CardDAV account too, instead of just the local addressbook. Thoughts?

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  • Best pattern for storing (product) attributes in SQL Server

    - by EdH
    We are starting a new project where we need to store product and many product attributes in a database. The technology stack is MS SQL 2008 and Entity Framework 4.0 / LINQ for data access. The products (and Products Table) are pretty straightforward (a SKU, manufacturer, price, etc..). However there are also many attributes to store with each product (think industrial widgets). These may range from color to certification(s) to pipe size. Every product may have different attributes, and some may have multiples of the same attribute (Ex: Certifications). The current proposal is that we will basically have a name/value pair table with a FK back to the product ID in each row. An example of the attributes Table may look like this: ProdID AttributeName AttributeValue 123 Color Blue 123 FittingSize 1.25 123 Certification AS1111 123 Certification EE2212 123 Certification FM.3 456 Pipe 11 678 Color Red 999 Certification AE1111 ... Note: Attribute name would likely come from a lookup table or enum. So the main question here is: Is this the best pattern for doing something like this? How will the performance be? Queries will be based on a JOIN of the product and attributes table, and generally need many WHEREs to filter on specific attributes - the most common search will be to find a product based on a set of known/desired attributes. If anyone has any suggestions or a better pattern for this type of data, please let me know. Thanks! -Ed

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  • How do you determine subtype of an entity using Inheritance with Entity Framework 4?

    - by KallDrexx
    I am just starting to use the Entity Framework 4 for the first time ever. So far I am liking it but I am a bit confused on how to correctly do inheritance. I am doing a model-first approach, and I have my Person entity with two subtype entities, Employee and Client. EF is correctly using the table per type approach, however I can't seem to figure out how to determine what type of a Person a specific object is. For example, if I do something like var people = from p in entities.Person select p; return people.ToList<Person>(); In my list that I form from this, all I care about is the Id field so i don't want to actually query all the subtype tables (this is a webpage list with links, so all I need is the name and the Id, all in the Persons table). However, I want to form different lists using this one query, one for each type of person (so one list for Clients and another for Employees). The issue is if I have a Person entity, I can't see any way to determine if that entity is a Client or an Employee without querying the Client or Employee tables directly. How can I easily determine the subtype of an entity without performing a bunch of additional database queries?

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  • Using Oracle hint "FIRST_ROWS" to improve Oracle database performances

    - by bobetko
    I have a statement that runs on Oracle database server. The statement has about 5 joins and there is nothing unusual there. It looks pretty much like below: SELECT field1, field2, field3, ... FROM table1, table2, table3, table4, table5 WHERE table1.id = table2.id AND table2.id = table3.id AND ... table5.userid = 1 The problem (and what is interesting) is that statement for userid = 1 takes 1 second to return 590 records. Statement for userid = 2 takes around 30 seconds to return 70 records. I don't understand why is difference so big. It seems that different execution plan is chosen for statement with userid = 1 and different for userid = 2. After I implemented Oracle Hint FIRST_ROW, performance become significantly better. Both statements (for both ids 1 and 2) produce return in under 1 second. SELECT /*+ FIRST_ROWS */ field1, field2, field3, ... FROM table1, table2, table3, table4, table5 WHERE table1.id = table2.id AND table2.id = table3.id AND ... table5.userid = 1 Questions: 1) What are possible reasons for bad performance when userid = 2 (when hint is not used)? 2) Why would execution plan be different for one vs another statement (when hint is not used)? 3) Is there anything that I should be careful about when deciding to add this hint to my queries? Thanks

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  • MVC and repository pattern data effeciency

    - by Shawn Mclean
    My project is structured as follows: DAL public IQueryable<Post> GetPosts() { var posts = from p in context.Post select p; return posts; } Service public IList<Post> GetPosts() { var posts = repository.GetPosts().ToList(); return posts; } //Returns a list of the latest feeds, restricted by the count. public IList<PostFeed> GetPostFeeds(int latestCount) { List<Post> post - GetPosts(); //CODE TO CREATE FEEDS HERE return feeds; } Lets say the GetPostFeeds(5) is supposed to return the 5 latest feeds. By going up the list, doesn't it pull down every single post from the database from GetPosts(), just to extract 5 from it? If each post is say 5kb from the database, and there is 1 million records. Wont that be 5GB of ram being used per call to GetPostFeeds()? Is this the way it happens? Should I go back to my DAL and write queries that return only what I need?

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  • Anybody seen this behavior with Sql Server Reporting Services, a 64bit OS and an Oracle datasource?

    - by dkackman
    I'm working on a Sql Server Reporting Services solution that queries across both a Sql Server data source and an Oracle 10g data source. My dev box is Windows 7 64bit with Sql Server 2008R2 and I'm hosting IIS7 and SSRS on that system for development; using VS.NET for designing the reports. I have been having errors when running the report where SSRS complains about loading the 32 bit Oracle client in a 64bit process. There a number of threads out there about how to solve that. The thing is, they all come down to making sure you have the 64bit Oracle, client which I do. The weird chain of events I have goes like this: Create initial Oracle datasource and wire up report (it works) Edit Oracle datasource connection (it stops working with BadImageFormatException 32bit/64bit error message) uninstall and reinstall Oracle client (it works) Edit Oracle connection again (it stops working with BadImageFormatException 32bit/64bit error message) So short of reinstalling the client every time I change the connection string I am at a complete loss. Has anybody seen this sort of behavior? And if so what the heck am I doing wrong?

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  • Annotation to make available generic type

    - by mdma
    Given an generic interface like interface DomainObjectDAO<T> { T newInstance(); add(T t); remove(T t); T findById(int id); // etc... } I'd like to create a subinterface that specifies the type parameter: interface CustomerDAO extends DomainObjectDAO<Customer> { // customer-specific queries - incidental. } The implementation needs to know the actual template parameter type, but of course type erasure means isn't available at runtime. Is there some annotation that I could include to declare the interface type? Something like @GenericParameter(Customer.class) interface CustomerDAO extends DomainObjectDAO<Customer> { } The implementation could then fetch this annotation from the interface and use it as a substitute for runtime generic type access. Some background: This interface is implemented using JDK dynamic proxies as outlined here. The non-generic version of this interface has been working well, but it would be nicer to use generics and not have to create a subinterface for each domain object type. The actual type is needed at runtime to implement the newInstance method, amongst others.

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  • Best way to manipulate and compare strings

    - by vtortola
    I'm developing a REST service, so a request could be something like this: /Data/Main/Table=Customers/ I need to get the segments one by one, and for each segment I will decide wich object I'm going to use, after I'll pass to that object the rest of the query so it can decide what to do next. Basically, the REST query is a path on a tree :P This imply lots String operations (depending on the query complexity), but StringBuilder is useful just for concatenations and remove, you cannot perform a search with IndexOf or similar. I've developed this class that fulfill my requirement, but the problem is that is manipulating Strings, so every time I get one segment ... I'll create extra Strings because String is an inmutable data type: public class RESTQueryParser { String _query; public RESTQueryParser(String query) { _query = query; } public String GetNext() { String result = String.Empty; Int32 startPosition = _query.StartsWith("/", StringComparison.InvariantCultureIgnoreCase) ? 1 : 0; Int32 i = _query.IndexOf("/", startPosition, StringComparison.InvariantCultureIgnoreCase) - 1; if (!String.IsNullOrEmpty(_query)) { if (i < 0) { result = _query.Substring(startPosition, _query.Length - 1); _query = String.Empty; } else { result = _query.Substring(startPosition, i); _query = _query.Remove(0, i + 1); } } return result; } } The server should support a lot of calls, and the queries could be huge, so this is gonna be a very repetitive task. I don't really know how big is the impact on the memory and the performance, I've just readed about it in some books. Should I implement a class that manage a Char[] instead Strings and implement the methods that I want? Or should be ok with this one? Regular expressions maybe?

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  • Feasibility of using Silverlight for web and windows client with common code base for data intensive

    - by Kabeer
    Hello. Recently in a conversation, someone suggested me to make use of Silverlight if I am targeting a web client and a windows client for the same application. This will cut down my effort for supporting the contrast in both presentation layers. Mine is a product, that will be deployed in enterprises. Both web and windows clients are desirable. With the above context, I have few queries: Is it advisable to adopt the recommended approach and whether this approach is becoming a trend? Besides, some configuration & deployment tweaking, will this significantly reduce effort on the presentation layer? Is there a possibility that my future prospects (for this product) will resist Silverlight footprint? Will I be able to make use of the ASP.Net MVC pattern? Will there be any performance implication for the web client? Will Silverlight support incremental load of controls? If my back-end includes SSRS, will I be able to harness all its front end features with Silverlight? Will I be able to support additional devices with same code base in future? Mine is a very data intensive application from both, data entry and reporting perspective. Is it advisable to use 3rd party controls (like Telerik) for improved user experience and developer productivity? Are their any professional quality open source Silverlight controls (library) available? Further, I seek information of best practices in the context I shared above.

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  • saxon java xpath exception :

    - by changed
    Hi I am trying to read XPath queries from a file and run it against a xml data file. I am doing it through Saxon Xpath processor. But i keep getting this error. Code i am using is from sample code provided with the library. Error i am getting is : Exception in thread "main" javax.xml.xpath.XPathExpressionException: Supplied node must be built using the same or a compatible Configuration at net.sf.saxon.xpath.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:283) at net.sf.saxon.xpath.XPathExpressionImpl.evaluate(XPathExpressionImpl.java:375) at edu.xml.XPathExample.go(XPathExample.java:81) at edu.xml.XPathExample.main(XPathExample.java:42) - public void go(String filename) throws Exception { XPathExpression findLine = null; String readLine = null; Object document = new XPathEvaluator().setSource(new StreamSource(new File(dataPath))); System.setProperty("javax.xml.xpath.XPathFactory:" + NamespaceConstant.OBJECT_MODEL_SAXON, "net.sf.saxon.xpath.XPathFactoryImpl"); XPathFactory xpf = XPathFactory.newInstance(NamespaceConstant.OBJECT_MODEL_SAXON); XPath xpe = xpf.newXPath(); if (filename != null) { this.queryPath = filename; } try { fileReader = new BufferedReader(new FileReader(queryPath)); } catch (FileNotFoundException ex) { System.out.println("File not found: " + ex.getMessage()); } xpe.setXPathVariableResolver(this); while (true) { try { readLine = fileReader.readLine(); } catch (IOException ex) { System.out.println("Error while reading file: " + ex.getMessage()); } if (readLine == null) { break; } findLine = xpe.compile(readLine); String resultString = findLine.evaluate(document); System.out.println("<output>"); System.out.println("String Value => " + resultString); System.out.println("</output>"); } }

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  • Complex SQL query... names of returned variables

    - by Andrew P.
    Excuse me for what I'm sure is an elementary question for most of you, but I have an issue with table columns from separate tables having the same name as one another, and trying to select from both tables in the same query. Okay, so this is my code: $q_value = $mdb2->quote($_POST['query']); $field = $_POST['field']; $sql = "SELECT m.*, l.name FROM memberlist m, mail_lists l WHERE m.$field=$q_value AND l.id = m.list ORDER BY m.id"; $l_list = $mdb2->queryAll($sql, '', 'MDB2_FETCHMODE_ASSOC'); The table memberlist has the following columns: id, email, list, sex, name and the table mail_lists has the following columns: id, name After running the query, I later loop through the results with a foreach like so: foreach ($l_list as $l){ //blahblah } The problem is that the column 'name' in mail_lists refers to the names of the list, while the column 'name' in memberlist refers to the name of the member. When I later access $l-name (within the foreach), will I get m.name, or l.name? Furthermore, how do I get access to the other? Or will I just have to do two separate queries?

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  • MySQL stuck on "using filesort" when doing an "order by"

    - by noko
    I can't seem to get my query to stop using filesort. This is my query: SELECT s.`pilot`, p.`name`, s.`sector`, s.`hull` FROM `pilots` p LEFT JOIN `ships` s ON ( (s.`game` = p.`game`) AND (s.`pilot` = p.`id`) ) WHERE p.`game` = 1 AND p.`id` <> 2 AND s.`sector` = 43 AND s.`hull` > 0 ORDER BY p.`last_move` DESC Table structures: CREATE TABLE IF NOT EXISTS `pilots` ( `id` mediumint(5) unsigned NOT NULL AUTO_INCREMENT, `game` tinyint(3) unsigned NOT NULL DEFAULT '0', `last_move` int(10) NOT NULL DEFAULT '0', UNIQUE KEY `id` (`id`), KEY `last_move` (`last_move`), KEY `game_id_lastmove` (`game`,`id`,`last_move`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ; CREATE TABLE IF NOT EXISTS `ships` ( `id` mediumint(5) unsigned NOT NULL AUTO_INCREMENT, `game` tinyint(3) unsigned NOT NULL DEFAULT '0', `pilot` mediumint(5) unsigned NOT NULL DEFAULT '0', `sector` smallint(5) unsigned NOT NULL DEFAULT '0', `hull` smallint(4) unsigned NOT NULL DEFAULT '50', UNIQUE KEY `id` (`id`), KEY `game` (`game`), KEY `pilot` (`pilot`), KEY `sector` (`sector`), KEY `hull` (`hull`), KEY `game_2` (`game`,`pilot`,`sector`,`hull`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=8 ; The explain: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE p ref id,game_id_lastmove game_id_lastmove 1 const 7 Using where; Using filesort 1 SIMPLE s ref game,pilot,sector... game_2 6 const,fightclub_alpha.p.id,const 1 Using where; Using index edit: I cut some of the unnecessary pieces out of my queries/table structure. Anybody have any ideas?

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  • Rich faces and dataTable

    - by ortho
    Hi all :) I have the question regarding rich faces and beans. I have a jsp page that is using richfaces and inside it I have the: rich:extendedDatatable component, that takes data from my MainBean as ArrayList (this bean queries the mySQL and puts results to the ArrayList that populates the dataTable later on). There are 4 columns in datatable, first 3 are h:outputLabels and the last one is checkbox. Now I have a question: how can I get information from selected row ? I mean, when user clicks checkbox, I want to take the id/name or whatever that is associated to this particular row, then when user clicks on Apply changed a4j: button I will update the database and when user logs in back again he will see updated info: e.g. checkbox is selected/not selected now because the user checked that. I believe that is a simple query for someone who worked with it. For me ex. flash developer it would be easy in as3, but here I didnt find the solution yet, please help. Thank you in advance, Kindest regards

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  • Linq PredicateBuilder with conditional AND, OR and NOT filters.

    - by richeym
    We have a project using LINQ to SQL, for which I need to rewrite a couple of search pages to allow the client to select whether they wish to perform an and or an or search. I though about redoing the LINQ queries using PredicateBuilder and have got this working pretty well I think. I effectively have a class containing my predicates, e.g.: internal static Expression<Func<Job, bool>> Description(string term) { return p => p.Description.Contains(term); } To perform the search i'm doing this (some code omitted for brevity): public Expression<Func<Job, bool>> ToLinqExpression() { var predicates = new List<Expression<Func<Job, bool>>>(); // build up predicates here if (SearchType == SearchType.And) { query = PredicateBuilder.True<Job>(); } else { query = PredicateBuilder.False<Job>(); } foreach (var predicate in predicates) { if (SearchType == SearchType.And) { query = query.And(predicate); } else { query = query.Or(predicate); } } return query; } While i'm reasonably happy with this, I have two concerns: The if/else blocks that evaluate a SearchType property feel like they could be a potential code smell. The client is now insisting on being able to perform 'and not' / 'or not' searches. To address point 2, I think I could do this by simply rewriting my expressions, e.g.: internal static Expression<Func<Job, bool>> Description(string term, bool invert) { if (invert) { return p => !p.Description.Contains(term); } else { return p => p.Description.Contains(term); } } However this feels like a bit of a kludge, which usually means there's a better solution out there. Can anyone recommend how this could be improved? I'm aware of dynamic LINQ, but I don't really want to lose LINQ's strong typing.

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  • Linq Query Performance , comparing Compiled query vs Non-Compiled.

    - by AG.
    Hello Guys, I was wondering if i extract the common where clause query into a common expression would it make my query much faster, if i have say something like 10 linq queries on a collection with exact same 1st part of the where clause. I have done a small example to explain a bit more . public class Person { public string First { get; set; } public string Last { get; set; } public int Age { get; set; } public String Born { get; set; } public string Living { get; set; } } public sealed class PersonDetails : List<Person> { } PersonDetails d = new PersonDetails(); d.Add(new Person() {Age = 29, Born = "Timbuk Tu", First = "Joe", Last = "Bloggs", Living = "London"}); d.Add(new Person() { Age = 29, Born = "Timbuk Tu", First = "Foo", Last = "Bar", Living = "NewYork" }); Expression<Func<Person, bool>> exp = (a) => a.Age == 29; Func<Person, bool> commonQuery = exp.Compile(); var lx = from y in d where commonQuery.Invoke(y) && y.Living == "London" select y; var bx = from y in d where y.Age == 29 && y.Living == "NewYork" select y; Console.WriteLine("All Details {0}, {1}, {2}, {3}, {4}", lx.Single().Age, lx.Single().First , lx.Single().Last, lx.Single().Living, lx.Single().Born ); Console.WriteLine("All Details {0}, {1}, {2}, {3}, {4}", bx.Single().Age, bx.Single().First, bx.Single().Last, bx.Single().Living, bx.Single().Born); So can some of the guru's here give me some advice if it would be a good practice to write query like var lx = "Linq Expression " or var bx = "Linq Expression" ? Any inputs would be highly appreciated. Thanks, AG

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  • should this database table be normalized?

    - by oo
    i have taken over a database that stores fitness information and we were having a debate about a certain table and whether it should stay as one table or get broken up into three tables. Today, there is one table called: workouts that has the following fields id, exercise_id, reps, weight, date, person_id So if i did 2 sets of 3 different exercises on one day, i would have 6 records in that table for that day. for example: id, exercise_id, reps, weight, date, person_id 1, 1, 10, 100, 1/1/2010, 10 2, 1, 10, 100, 1/1/2010, 10 3, 1, 10, 100, 1/1/2010, 10 4, 2, 10, 100, 1/1/2010, 10 5, 2, 10, 100, 1/1/2010, 10 6, 2, 10, 100, 1/1/2010, 10 So the question is, given that there is some redundant data (date, personid, exercise_id) in multiple records, should this be normalized to three tables WorkoutSummary: - id - date - person_id WorkoutExercise: - id - workout_id (foreign key into WorkoutSummary) - exercise_id WorkoutSets: - id - workout_exercise_id (foreign key into WorkoutExercise) - reps - weight I would guess the downside is that the queries would be slower after this refactoring as now we would need to join 3 tables to do the same query that had no joins before. The benefit of the refactoring allows up in the future to add new fields at the workout summary level or the exercise level with out adding in more duplication. any feedback on this debate?

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  • Cannot Cache NHibernate Future Criteria Results

    - by Emilian
    I have the following code: public void FuturesQuery() { using (var session = SessionFactory.OpenSession()) { var blogs = session.CreateCriteria<Blog>() .SetMaxResults(5) .SetCacheable(true) .SetCacheMode(CacheMode.Normal) .SetCacheRegion("BlogQuery") .Future<Blog>(); var countOfBlogs = session.CreateCriteria<Blog>() .SetProjection(Projections.Count(Projections.Id())) .SetCacheable(true) .SetCacheMode(CacheMode.Normal) .SetCacheRegion("BlogQuery") .FutureValue<int>(); Console.WriteLine("Number of blogs: {0}", countOfBlogs.Value); foreach (var blog in blogs) { Console.WriteLine(blog.Title); } } using (var session = SessionFactory.OpenSession()) { var blogs = session.CreateCriteria<Blog>() .SetMaxResults(5) .SetCacheable(true) .SetCacheMode(CacheMode.Normal) .SetCacheRegion("BlogQuery") .Future<Blog>(); var countOfBlogs = session.CreateCriteria<Blog>() .SetProjection(Projections.Count(Projections.Id())) .SetCacheable(true) .SetCacheMode(CacheMode.Normal) .SetCacheRegion("BlogQuery") .FutureValue<int>(); Console.WriteLine("Number of blogs: {0}", countOfBlogs.Value); foreach (var blog in blogs) { Console.WriteLine(blog.Title); } } } I was expecting that the second time I query for blogs and count of blogs I will get values from cache but instead the queries hit the database. If I don't use Futures I get the expected results. Does this means that results from Criteria using futures cannot be cached?

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  • Poor Ruby on Rails performance when using nested :include

    - by Jeremiah Peschka
    I have three models that look something like this: class Bucket < ActiveRecord::Base has_many :entries end class Entry < ActiveRecord::Base belongs_to :submission belongs_to :bucket end class Submission < ActiveRecord::Base has_many :entries belongs_to :user end class User < ActiveRecord::Base has_many :submissions end When I retrieve a collection of entries doing something like: @entries = Entry.find(:all, :conditions => ['entries.bucket_id = ?', @bucket], :include => :submission) The performance is pretty quick although I get a large number of extra queries because the view uses the Submission.user object. However, if I add the user to the :include statement, the performance becomes terrible and it takes over a minute to return a total of 50 entries and submissions spread across 5 users. When I run the associated SQL commands, they complete in well under a second. @entries = Entry.find(:all, :conditions => ['entries.bucket_id = ?', @bucket], :include => {:submission => :user}) Why would this second command have such terrible performance compared to the first?

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  • Data in two databases, eager spool resulting in query

    - by Valkyrie
    I have two databases in SQL2k5: one that holds a large amount of static data (SQL Database 1) (never updated but frequently inserted into) and one that holds relational data (SQL Database 2) related to the static data. They're separated mainly because of corporate guidelines and business requirements: assume for the following problem that combining them is not practical. There are places in SQLDB2 that PKs in SQLDB1 are referenced; triggers control the referential integrity, since cross-database relationships are troublesome in SQL Server. BUT, because of the large amount of data in SQLDB1, I'm getting eager spools on queries that join from the Id in SQLDB2 that references the data in SQLDB1. (With me so far? Maybe an example will help:) SELECT t.Id, t.Name, t2.Company FROM SQLDB1.table t INNER JOIN SQLDB2.table t2 ON t.Id = t2.FKId This query results in a eager spool that's 84% of the load of the query; the table in SQLDB1 has 35M rows, so it's completely choking this query. I can't create a view on the table in SQLDB1 and use that as my FK/index; it doesn't want me to create a constraint based on a view. Anyone have any idea how I can fix this huge bottleneck? (Short of putting the static data in the first db: believe me, I've argued that one until I'm blue in the face to no avail.) Thanks! valkyrie Edit: also can't create an indexed view because you can't put schemabinding on a view that references a table outside the database where the view resides. Dang it.

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  • MVC and repository pattern data efficiency

    - by Shawn Mclean
    My project is structured as follows: DAL public IQueryable<Post> GetPosts() { var posts = from p in context.Post select p; return posts; } Service public IList<Post> GetPosts() { var posts = repository.GetPosts().ToList(); return posts; } //Returns a list of the latest feeds, restricted by the count. public IList<PostFeed> GetPostFeeds(int latestCount) { List<Post> post - GetPosts(); //CODE TO CREATE FEEDS HERE return feeds; } Lets say the GetPostFeeds(5) is supposed to return the 5 latest feeds. By going up the list, doesn't it pull down every single post from the database from GetPosts(), just to extract 5 from it? If each post is say 5kb from the database, and there is 1 million records. Wont that be 5GB of ram being used per call to GetPostFeeds()? Is this the way it happens? Should I go back to my DAL and write queries that return only what I need?

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  • How do i write this jpql query?

    - by Nitesh Panchal
    Hello, Say i have 5 tables, tblBlogs tblBlogPosts tblBlogPostComment tblUser tblBlogMember BlogId BlogPostsId BlogPostCommentId UserId BlogMemberId BlogTitle BlogId CommentText FirstName UserId PostTitle BlogPostsId BlogId BlogMemberId Now i want to retrieve only those blogs and posts for which blogMember has actually commented. So in short, how do i write this plain old sql :- Select b.BlogTitle, bp.PostTitle, bpc.CommentText from tblBlogs b Inner join tblBlogPosts bp on b.BlogId = bp.BlogId Inner Join tblBlogPostComment bpc on bp.BlogPostsId = bpc.BlogPostsId Inner Join tblBlogMember bm On bpc.BlogMemberId = bm.BlogMemberId Where bm.UserId = 1; As you can see, everything is Inner join, so only that row will be retrieved for which the user has commented on some post of some blog. So, suppose he has joined 3 blogs whose ids are 1,2,3 (The blogs which user has joined are in tblBlogMembers) but the user has only commented in blog 2 (of say BlogPostId = 1). So that row will be retrieved and 1,3 won't as it is Inner Join. How do i write this kind of query in jpql? In jpql, we can only write simple queries like say :- Select bm.blogId from tblBlogMember Where bm.UserId = objUser; Where objUser is supplied using :- em.find(User.class,1); Thus once we get all blogs(Here blogId represents a blog object) which user has joined, we can loop through and do all fancy things. But i don't want to fall in this looping business and write all this things in my java code. Instead, i want to leave that for database engine to do. So, how do i write the above plain sql into jpql? and what type of object the jpql query will return? because i am only selecting few fields from all table. In which class should i typecast the result to? I think i posted my requirement correctly, if i am not clear please let me know. Thanks in advance :).

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