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• Combining SQL Rows

  - by lumberjack4

  I've got SQL Compact Database that contains a table of IP Packet Headers. The Table looks like this: Table: PacketHeaders ID SrcAddress SrcPort DestAddress DestPort Bytes 1 10.0.25.1 255 10.0.25.50 500 64 2 10.0.25.50 500 10.0.25.1 255 80 3 10.0.25.50 500 10.0.25.1 255 16 4 75.48.0.25 387 74.26.9.40 198 72 5 74.26.9.40 198 75.48.0.25 387 64 6 10.0.25.1 255 10.0.25.50 500 48 I need to perform a query to show 'conversations' going on across a local network. Packets going from A - B is part of the same conversations as packets going from B - A. I need to perform a query to show the on going conversations. Basically what I need is something that looks like this: Returned Query: SrcAddress SrcPort DestAddress DestPort TotalBytes BytesA->B BytesB->A 10.0.25.1 255 10.0.25.50 500 208 112 96 75.48.0.25 387 74.26.9.40 198 136 72 64 As you can see I need the query (or series of queries) to recognize that A-B is the same as B-A and break up the byte counts accordingly. I'm not a SQL guru by any means but any help on this would be greatly appreciated.

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• AppEngine JDO-QL : Problem with multiple AND and OR in query

  - by KlasE

  Hi, I'm working with App Engine(Java/JDO) and are trying to do some querying with lists. So I have the following class: @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") public class MyEntity { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) Key key; @Persistent List<String> tags = new ArrayList<String>(); @Persistent String otherVar; } The following JDO-QL works for me: ( tags.contains('a') || tags.contains('b') || tags.contains('c') || tags.contains('d') ) && otherVar > 'a' && otherVar < 'z' This seem to return all results where tags has one or more strings with one or more of the given values and together with the inequality search on otherVar But the following do not work: (tags.contains('a') || tags.contains('_a')) && (tags.contains('b') || tags.contains('_b')) && otherVar > 'a' && otherVar < 'z' In this case I want all hits where there is at least one a (either a or _a) and one b (either b or _b) together with the inequality search as before. But the problem is that I also get back the results where there is a but no b, which is not what I want. Maybe I have missed something obvious, or done a coding error, or possibly there is a restriction on how you can write these queries in appengine, so any tips or help would be very welcome. Regards Klas

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• Linq to XML Document Traversal

  - by Perpetualcoder

  I have an xml document like this: <?xml version="1.0" encoding="utf-8" ?> <demographics> <country id="1" value="USA"> <state id ="1" value="California"> <city>Long Beach</city> <city>Los Angeles</city> <city>San Diego</city> </state> <state id ="2" value="Arizona"> <city>Tucson</city> <city>Phoenix</city> <city>Tempe</city> </state> </country> <country id="2" value="Mexico"> <state id ="1" value="Baja California"> <city>Tijuana</city> <city>Rosarito</city> </state> </country> </demographics> How do I setup LINQ queries for doing things like: 1. Get All Countries 2. Get All States in a Country 3. Get All Cities inside a state of a paricular country ? I gave it a try and I am kind of confused when to use Elements["NodeName"] and Descendants etc. I know I am not the brightest XML guy around. Is the format of the XML file even correct for simple traversal?

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• Need help choosing database server

  - by The Pretender

  Good day everyone. Recently I was given a task to develop an application to automate some aspects of stocks trading. While working on initial architecture, the database dilemma emerged. What I need is a fast database engine which can process huge amounts of data coming in very fast. I'm fairly experienced in general programming, but I never faced a task of developing a high-load database architecture. I developed a simple MSSQL database schema with several many-to-many relationships during one of my projects, but that's it. What I'm looking for is some advice on choosing the most suitable database engine and some pointers to various manuals or books which describe high-load database development. Specifics of the project are as follows: OS: Windows NT family (Server 2008 / 7) Primary platform: .NET with C# Database structure: one table to hold primary items and two or three tables with foreign keys to the first table to hold additional information. Database SELECT requirements: Need super-fast selection by foreign keys and by combination of foreign key and one of the columns (presumably DATETIME) Database INSERT requirements: The faster the better :) If there'll be significant performance gain, some parts can be written in C++ with managed interfaces to the rest of the system. So once again: given all that stuff I just typed, please give me some advice on what the best database for my project is. Links or references to some manuals and books on the subject are also greatly appreciated. EDIT: I'll need to insert 3-5 rows in 2 tables approximately once in 30-50 milliseconds and I'll need to do SELECT with 0-2 WHERE clauses queries with similar rate.

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• Use the repository pattern when using PLINQO generated data?

  - by Chad

  I'm "upgrading" an MVC app. Previously, the DAL was a part of the Model, as a series of repositories (based on the entity name) using standard LINQ to SQL queries. Now, it's a separate project and is generated using PLINQO. Since PLINQO generates query extensions based on the properties of the entity, I started using them directly in my controller... and eliminated the repositories all together. It's working fine, this is more a question to draw upon your experience, should I continue down this path or should I rebuild the repositories (using PLINQO as the DAL within the repository files)? One benefit of just using the PLINQO generated data context is that when I need DB access, I just make one reference to the the data context. Under the repository pattern, I had to reference each repository when I needed data access, sometimes needing to reference multiple repositories on a single controller. The big benefit I saw on the repositories, were aptly named query methods (i.e. FindAllProductsByCategoryId(int id), etc...). With the PLINQO code, it's _db.Product.ByCatId(int id) - which isn't too bad either. I like both, but where it gets "harrier" is when the query uses predicates. I can roll that up into the repository query method. But on the PLINQO code, it would be something like _db.Product.Where(x = x.CatId == 1 && x.OrderId == 1); I'm not so sure I like having code like that in my controllers. Whats your take on this?

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• Why use SQL database?

  - by martinthenext

  I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try. Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases, most of all software products, frameworks, etc. It is rather hard for a beginning developer like me to ask a question - why? Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so we need relations between database objects too. This leads us to using relational database and I'm ok with that - to put it simple, our database rows sometimes will need to have references to other tables' rows. But why do use SQL language for interaction with such a database? SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that. What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?

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• Database Design Question regaurding duplicate information.

  - by galford13x

  I have a database that contains a history of product sales. For example the following table CREATE TABLE SalesHistoryTable ( OrderID, // Order Number Unique to all orders ProductID, // Product ID can be used as a Key to look up product info in another table Price, // Price of the product per unit at the time of the order Quantity, // quantity of the product for the order Total, // total cost of the order for the product. (Price * Quantity) Date, // Date of the order StoreID, // The store that created the Order PRIMARY KEY(OrderID)); The table will eventually have millions of transactions. From this, profiles can be created for products in different geographical regions (based on the StoreID). Creating these profiles can be very time consuming as a database query. For example. SELECT ProductID, StoreID, SUM(Total) AS Total, SUM(Quantity) QTY, SUM(Total)/SUM(Quantity) AS AvgPrice FROM SalesHistoryTable GROUP BY ProductID, StoreID; The above query could be used to get the Information based on products for any particular store. You could then determine which store has sold the most, has made the most money, and on average sells for the most/least. This would be very costly to use as a normal query run anytime. What are some design descisions in order to allow these types of queries to run faster assuming storage size isn’t an issue. For example, I could create another Table with duplicate information. Store ID (Key), Product ID, TotalCost, QTY, AvgPrice And provide a trigger so that when a new order is received, the entry for that store is updated in a new table. The cost for the update is almost nothing. What should be considered when given the above scenario?

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• Impact of ordering of correlated subqueries within a projection

  - by Michael Petito

  I'm noticing something a bit unexpected with how SQL Server (SQL Server 2008 in this case) treats correlated subqueries within a select statement. My assumption was that a query plan should not be affected by the mere order in which subqueries (or columns, for that matter) are written within the projection clause of the select statement. However, this does not appear to be the case. Consider the following two queries, which are identical except for the ordering of the subqueries within the CTE: --query 1: subquery for Color is second WITH vw AS ( SELECT p.[ID], (SELECT TOP(1) [FirstName] FROM [Preference] WHERE p.ID = ID AND [FirstName] IS NOT NULL ORDER BY [LastModified] DESC) [FirstName], (SELECT TOP(1) [Color] FROM [Preference] WHERE p.ID = ID AND [Color] IS NOT NULL ORDER BY [LastModified] DESC) [Color] FROM Person p ) SELECT ID, Color, FirstName FROM vw WHERE Color = 'Gray'; --query 2: subquery for Color is first WITH vw AS ( SELECT p.[ID], (SELECT TOP(1) [Color] FROM [Preference] WHERE p.ID = ID AND [Color] IS NOT NULL ORDER BY [LastModified] DESC) [Color], (SELECT TOP(1) [FirstName] FROM [Preference] WHERE p.ID = ID AND [FirstName] IS NOT NULL ORDER BY [LastModified] DESC) [FirstName] FROM Person p ) SELECT ID, Color, FirstName FROM vw WHERE Color = 'Gray'; If you look at the two query plans, you'll see that an outer join is used for each subquery and that the order of the joins is the same as the order the subqueries are written. There is a filter applied to the result of the outer join for color, to filter out rows where the color is not 'Gray'. (It's odd to me that SQL would use an outer join for the color subquery since I have a non-null constraint on the result of the color subquery, but OK.) Most of the rows are removed by the color filter. The result is that query 2 is significantly cheaper than query 1 because fewer rows are involved with the second join. All reasons for constructing such a statement aside, is this an expected behavior? Shouldn't SQL server opt to move the filter as early as possible in the query plan, regardless of the order the subqueries are written?

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• Accessing Unicode telugu text from Ms-Access Database in Java

  - by Ravi Chandra

  I have an MS-Access database ( A English-telugu Dictionary database) which contains a table storing English words and telugu meanings. I am writing a dictionary program in Java which queries the database for a keyword entered by the user and display the telugu meaning. My Program is working fine till I get the data from the database, but when I displayed it on some component like JTextArea/JEditorPane/ etc... the telugu text is being displayed as '????'. Why is it happening?. I have seen the solution for "1467412/reading-unicode-data-from-an-access-database-using-jdbc" which provides some workaround for Hebrew language. But it is not working for telugu. i.e I included setCharset("UTF8")before querying from the database. but still I am getting all '?'s. As soon as I got data from Resultset I am checking the individual characters, all the telugu characters are being encoded by 63 only. This is my observation. I guess this must be some type of encoding problem. I would be very glad if somebody provides some solution for this. Thanks in advance.

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• Does WPF break an Entity Framework ObjectContext?

  - by David Veeneman

  I am getting started with Entity Framework 4, and I am getting ready to write a WPF demo app to learn EF4 better. My LINQ queries return IQueryable<T>, and I know I can drop those into an ObservableCollection<T> with the following code: IQueryable<Foo> fooList = from f in Foo orderby f.Title select f; var observableFooList = new ObservableCollection<Foo>(fooList); At that point, I can set the appropriate property on my view model to the observable collection, and I will get WPF data binding between the view and the view model property. Here is my question: Do I break the ObjectContext when I move my foo list to the observable collection? Or put another way, assuming I am otherwise handling my ObjectContext properly, will EF4 properly update the model (and the database)? The reason why I ask is this: NHibernate tracks objects at the collection level. If I move an NHibernate IList<T> to an observable collection, it breaks NHibernate's change tracking mechanism. That means I have to do some very complicated object wrapping to get NHibernate to work with WPF. I am looking at EF4 as a way to dispense with all that. So, to get EF4 working with WPF, is it as simple as dropping my IQueryable<T> results into an ObservableCollection<T>. Does that preserve change-tracking on my EDM entity objects? Thanks for your help.

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• Query eror handling in CodeIgniter

  - by Sajith S Narayanan

  Hi All, I am trying to execute an MySql query using the CI Active methods. If the query is malformed, then CI invokes internal server error 500 and quits without processing the next steps.. I need to roll back all the other queries processed before that error statement, and the roll back is also not happening.. can you help pls. The code snippets is as below: function dbInsertInformationToDB($data_array) { $returnID = ""; $uniqueDataArray = array(); // I prepare a array of values here $uniqueTableList = filter_unique_tables($data_array[2]); $this->db->trans_begin(); // inserting is done here // when there is a query error in $this->db->insert().. it is not rolling back the previous query executed foreach($uniqueTableList as $table_name) { $uniqueDataArray = filterDataArray($data_array,$table_name,2); $this->db->insert($table_name,$uniqueDataArray); if ($this->db->_error_message()) { $error = "I am caught!!"; } $returnID = $this->db->affected_rows(); } if ($this->db->trans_status() === FALSE) { $this->db->trans_rollback(); } else { $this->db->trans_commit(); } return "ERROR"; }

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• Way to automate setting of MergeOptions

  - by Nix

  I am looking for an automated way to iterate over all ObjectQueries and set the merge option to no tracking (read only context). Once i find out how to do it i will be able to generate a default read only context using a T4 template. Is this possible? For example lets say i have these tables in my object context SampleContext TableA TableB TableC I would have to go through and do the below. SampleContext sc = new SampleContext(); sc.TableA.MergeOption = MergeOption.NoTracking; sc.TableB.MergeOption = MergeOption.NoTracking; sc.TableC.MergeOption = MergeOption.NoTracking; I am trying to find a way to generalize this using object context. I want to get it down to something like foreach(var objectQuery : sc){ objectQuery.MergeOption = MergeOption.NoTracking; } Preferably I would like to do it using the baseclass(ObjectContext): ObjectContext baseClass = sc as ObjectContext var objectQueries = sc.MetadataWorkspace.GetItem("Magic Object Query Option); But i am not sure i can even get access to the queries. Any help would be appreciated.

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• Python SQLite FTS3 alternatives?

  - by Mike Cialowicz

  Are there any good alternatives to SQLite + FTS3 for python? I'm iterating over a series of text documents, and would like to categorize them according to some text queries. For example, I might want to know if a document mentions the words "rating" or "upgraded" within three words of "buy." The FTS3 syntax for this query is the following: (rating OR upgraded) NEAR/3 buy That's all well and good, but if I use FTS3, this operation seems rather expensive. The process goes something like this: # create an SQLite3 db in memory conn = sqlite3.connect(':memory:') c = conn.cursor() c.execute('CREATE VIRTUAL TABLE fts USING FTS3(content TEXT)') conn.commit() Then, for each document, do something like this: #insert the document text into the fts table, so I can run a query c.execute('insert into fts(content) values (?)', content) conn.commit() # execute my FTS query here, look at the results, etc # remove the document text from the fts table before working on the next document c.execute('delete from fts') conn.commit() This seems rather expensive to me. The other problem I have with SQLite FTS is that it doesn't appear to work with Python 2.5.4. The 'CREATE VIRTUAL TABLE' syntax is unrecognized. This means that I'd have to upgrade to Python 2.6, which means re-testing numerous existing scripts and programs to make sure they work under 2.6. Is there a better way? Perhaps a different library? Something faster? Thank you.

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• Using LINQ to SQL and chained Replace

  - by White Dragon

  I have a need to replace multiple strings with others in a query from p in dx.Table where p.Field.Replace("A", "a").Replace("B", "b").ToLower() = SomeVar select p Which provides a nice single SQL statement with the relevant REPLACE() sql commands. All good :) I need to do this in a few queries around the application... So i'm looking for some help in this regard; that will work as above as a single SQL hit/command on the server It seems from looking around i can't use RegEx as there is no SQL eq Being a LINQ newbie is there a nice way for me to do this? eg is it possible to get it as a IQueryable "var result" say and pass that to a function to add needed .Replace()'s and pass back? Can i get a quick example of how if so? EDIT: This seems to work! does it look like it would be a problem? var data = from p in dx.Videos select p; data = AddReplacements(data, checkMediaItem); theitem = data.FirstOrDefault(); ... public IQueryable<Video> AddReplacements(IQueryable<Video> DataSet, string checkMediaItem) { return DataSet.Where(p => p.Title.Replace(" ", "-").Replace("&", "-").Replace("?", "-") == checkMediaItem); }

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• Saving twice don't update my object in JDO

  - by Javi

  Hello I have an object persisted in the GAE datastore using JDO. The object looks like this: public class MyObject implements Serializable, StoreCallback { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String id; @Persistent private String firstId; ... } As usually when the object is stored for the first time a new id value is generated for the identifier. I need that if I don't provide a value for firstId it sets the same value as the id. I don't want to solve it with a special getter which checks for null value in firstId and then return the id value because I want to make queries relating on firstId. I can do it in this way by saving the object twice (Probably there's a better way to do this, but I'll do it in this way until I find a better one). But it is not working. when I debug it I can see that result.firstId is set with the id value and it seems to be persisted, but when I go into the datastore I see that firstId is null (as it was saved the first time). This save method is in my DAO and it is called in another save method in the service annotated with @Transactional. Does anyone have any idea why the second object in not persisted properly? @Override public MyObject save(MyObject obj) { PersistenceManager pm = JDOHelper.getPersistenceManagerFactory("transactions-optional"); MyObject result = pm.makePersistent(obj); if(result.getFirstId() == null){ result.setFirstId(result.getId()); result = pm.makePersistent(result); } return result; } Thanks.

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• Top 10 collection completion - a monster in-query formula in MySQL?

  - by Andrew Heath

  I've got the following tables: User Basic Data (unique) [userid] [name] [etc] User Collection (one to one) [userid] [game] User Recorded Plays (many to many) [userid] [game] [scenario] [etc] Game Basic Data (unique) [game] [total_scenarios] I would like to output a table that shows the collection play completion percentage for the Top 10 users in descending order of %: Output Table [userid] [collection_completion] 3 95% 1 81% 24 68% etc etc In my mind, the calculation sequence for ONE USER is: grab user's total owned scenarios from User Collection joined with Game Basic Data and COUNT(gbd.total_scenarios) grab all recorded plays by COUNT(DISTINCT scenario) for that user Divide all recorded plays by total owned scenarios So that's 2 queries and a little PHP massage at the end. For a list of users sorted by completion percentage things get a little more complicated. I figure I could grab all users' collection totals in one query, and all users recorded plays in another, and then do the calcs and sort the final array in PHP, but it seems like overkill to potentially be doing all that for 1000+ users when I only ever want the Top 10. Is there a wicked monster query in MySQL that could do all that and LIMIT 10? Or is sticking with PHP handling the bulk of the work the way to go in this case?

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• Grails - Recursive computing call "StackOverflowError" and don't update on show

  - by Kedare

  Hello, I have a little problem, I have made a Category domain on Grails, but I want to "cache" the string representation on the database by generating it when the representation field is empty or NULL (to avoid recursive queries at each toString), here is the code : package devkedare class Category { String title; String description; String representation; Date dateCreated; Date lastUpdate; Category parent; static constraints = { title(blank:false, nullable:false, size:2..100); description(blank:true, nullable:false); dateCreated(nullable:true); lastUpdate(nullable:true); autoTimestamp: true; } static hasMany = [childs:Category] @Override String toString() { if((!this.representation) || (this.representation == "")) { this.computeRepresentation(true) } return this.representation; } String computeRepresentation(boolean updateChilds) { if(updateChilds) { for(child in this.childs) { child.representation = child.computeRepresentation(true); } } if(this.parent) { this.representation = "${this.parent.computeRepresentation(false)}/${this.title}"; } else { this.representation = this.title } return this.representation; } void beforeUpdate() { this.computeRepresentation(true); } } There is 2 problems : It don't update the representation when the representation if NULL or empty and toString id called, it only update it on save, how to fix that ? On some category, updating it throw a StackOverflowError, here is an example of my actual category table as CSV : Uploaded the csv file here, pasting csv looks buggy: http://kedare.free.fr/Dist/01.csv Updating the representation works everywhere except on "IT" that throw a StackOverlowError (this is the only category that has many childs). Any idea of how can I fix those 2 problems ? Thank you !

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• rapid application developement tools for very basic GUI apps

  - by Jurij

  I know there are many RAD platforms out there. Infact there are so many that I'm having a hard time finding out which one fits me best. What I want is a RAD tool that would allow me to define a database data model (make DB tables) and then create (view and edit) forms for the various tables. Data input, updating and various queries should be easy and GUI should generate automatically. I'd like to add some additional functionality by coding (such as various complex calculations on the data). I'm a programmer so I'm willing to learn to use a more complete, full-blown RAD solution if you can point me to it (NetBeans and RubyOnRails being the two such frameworks that I'd would probably be high on the list). I'm currently doing Windows Forms logistics apps in .NET. I've actually developed a very crude and basic version of what I need, but I just know that there are solutions out there that are much better and I'd benefit by knowing how to use them. So in short, the basic requirements: * database based data storage (SQLite if possible) * very automated GUI creation * desktop based (as in: not a web app) * extendable by coding * used for creating simple data entry, view & query apps. So basically something like Oracle Forms or DotNetMushroom Rapid Application Developer. But for .NET and SQLite if possible.

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• Delphi Application using COMMIT and ROLLBACK for Multiple SQL Updates

  - by Matt

  Is it possible to use the SQL BEGIN TRANSACTION, COMMIT TRANSACTION, ROLLBACK TRANSACTION when embedding SQL Queries into an application with mutiple calls to the SQL for Table Updates. For example I have the following code: Q.SQL.ADD(<UPDATE A RECORD>); Q.ExecSQL; Q.Close; Q.SQL.Clear; Q.SQL.ADD(<Select Some Data>); Q.Open; Set Some Variables Q.Close; Q.SQL.Clear; Q.SQL.ADD(<UPDATE A RECORD>); Q.ExecSQL; What I would like to do is if the second update fails I want to roll back the first transaction. If I set a unique notation for the BEGIN, COMMIT, ROLLBACK so as to specify what is being committed or rolled back, is it feasible. i.e. before the first Update specify BEGIN TRANSACTION_A then after the last update specify COMMIT TRANSACTION_A I hope that makes sense. If I was doing this in a SQL Stored Procedure then I would be able to specify this at the start and end of the procedure, but I have had to break the code down into manageable chunks due to process blocks and deadlocks on a heavy loaded SQL Server.

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• How to profile Doctrine in Zend Framework

  - by David Zapata

  Good day. I'm using Doctrine as ORM for my Zend Framework project. This is the first time I use it. I've followed the ZendCasts Doctrine chapters, and everything works for me, but I needed to perform some profiling; There is a Doctrine_Connection_Profiler class that should be used to profile the Doctrine Model internal queries, but I've tried to use it without success. I always get a "PDOException: You cannot serialize or unserialize PDOStatement instances" exception when I perform my Unit Tests. Here is a example: $conn = Doctrine_Manager::connection($doctrineConfig['dsn'], $dbconfname); ... if( APPLICATION_ENV != 'production'){ $obj_doctrine_profiler = new Doctrine_Connection_Profiler(); $conn->setListener($obj_doctrine_profiler); } All of my Unit Tests works if I comment/delete the $conn->setListener($obj_doctrine_profiler); line. This code block is located in my Bootstrap.php class; the weird thing is, the web application works just fine even with the mentioned code line. Thank you so much for your help. please excuse me if my english is not the best.

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• What's the fastest way to bulk insert a lot of data in SQL Server (C# client)

  - by Andrew

  I am hitting some performance bottlenecks with my C# client inserting bulk data into a SQL Server 2005 database and I'm looking for ways in which to speed up the process. I am already using the SqlClient.SqlBulkCopy (which is based on TDS) to speed up the data transfer across the wire which helped a lot, but I'm still looking for more. I have a simple table that looks like this: CREATE TABLE [BulkData]( [ContainerId] [int] NOT NULL, [BinId] [smallint] NOT NULL, [Sequence] [smallint] NOT NULL, [ItemId] [int] NOT NULL, [Left] [smallint] NOT NULL, [Top] [smallint] NOT NULL, [Right] [smallint] NOT NULL, [Bottom] [smallint] NOT NULL, CONSTRAINT [PKBulkData] PRIMARY KEY CLUSTERED ( [ContainerIdId] ASC, [BinId] ASC, [Sequence] ASC )) I'm inserting data in chunks that average about 300 rows where ContainerId and BinId are constant in each chunk and the Sequence value is 0-n and the values are pre-sorted based on the primary key. The %Disk time performance counter spends a lot of time at 100% so it is clear that disk IO is the main issue but the speeds I'm getting are several orders of magnitude below a raw file copy. Does it help any if I: Drop the Primary key while I am doing the inserting and recreate it later Do inserts into a temporary table with the same schema and periodically transfer them into the main table to keep the size of the table where insertions are happening small Anything else? -- Based on the responses I have gotten, let me clarify a little bit: Portman: I'm using a clustered index because when the data is all imported I will need to access data sequentially in that order. I don't particularly need the index to be there while importing the data. Is there any advantage to having a nonclustered PK index while doing the inserts as opposed to dropping the constraint entirely for import? Chopeen: The data is being generated remotely on many other machines (my SQL server can only handle about 10 currently, but I would love to be able to add more). It's not practical to run the entire process on the local machine because it would then have to process 50 times as much input data to generate the output. Jason: I am not doing any concurrent queries against the table during the import process, I will try dropping the primary key and see if that helps. ~ Andrew

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• ASP.NET MVC intermittent slow response

  - by arehman

  Problem In our production environment, system occasionally delays the page response of an ASP.NET MVC application up to 30 seconds or so, even though same page renders in 2-3 seconds most of the times. This happens randomly with any arbitrary page, and GET or POST type requests. For example, log files indicates, system took 15 seconds to complete a request for jquery script file or for other small css file it took 10 secs. Similar Problems: Random Slow Downs Production Environment: Windows Server 2008 - Standard (32-bit) - App Pool running in integrated mode. ASP.NET MVC 1.0 We have tried followings/observations: Moved the application to a stand alone web server, but, it didn't help. We didn't ever notice same issue on the server for any 'ASP.NET' application. App Pool settings are fine. No abrupt recycles/shutdowns. No cpu spikes or memory problems. No delays due to SQL queries or so. It seems as something causing delay along HTTP Pipeline or worker processor seeing the request late. Looking for other suggestions. -- Thanks

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• Got a table of people, who I want to link to each other, many-to-many, with the links being bidirect

  - by dflock

  Imagine you live in very simplified example land - and imagine that you've got a table of people in your MySQL database: create table person ( person_id int, name text ) select * from person; +-------------------------------+ | person_id | name | +-------------------------------+ | 1 | Alice | | 2 | Bob | | 3 | Carol | +-------------------------------+ and these people need to collaborate/work together, so you've got a link table which links one person record to another: create table person__person ( person__person_id int, person_id int, other_person_id int ) This setup means that links between people are uni-directional - i.e. Alice can link to Bob, without Bob linking to Alice and, even worse, Alice can link to Bob and Bob can link to Alice at the same time, in two separate link records. As these links represent working relationships, in the real world they're all two-way mutual relationships. The following are all possible in this setup: select * from person__person; +---------------------+-----------+--------------------+ | person__person_id | person_id | other_person_id | +---------------------+-----------+--------------------+ | 1 | 1 | 2 | | 2 | 2 | 1 | | 3 | 2 | 2 | | 4 | 3 | 1 | +---------------------+-----------+--------------------+ For example, with person__person_id = 4 above, when you view Carol's (person_id = 3) profile, you should see a relationship with Alice (person_id = 1) and when you view Alice's profile, you should see a relationship with Carol, even though the link goes the other way. I realize that I can do union and distinct queries and whatnot to present the relationships as mutual in the UI, but is there a better way? I've got a feeling that there is a better way, one where this issue would neatly melt away by setting up the database properly, but I can't see it. Anyone got a better idea?

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• When *not* to use prepared statements?

  - by Ben Blank

  I'm re-engineering a PHP-driven web site which uses a minimal database. The original version used "pseudo-prepared-statements" (PHP functions which did quoting and parameter replacement) to prevent injection attacks and to separate database logic from page logic. It seemed natural to replace these ad-hoc functions with an object which uses PDO and real prepared statements, but after doing my reading on them, I'm not so sure. PDO still seems like a great idea, but one of the primary selling points of prepared statements is being able to reuse them… which I never will. Here's my setup: The statements are all trivially simple. Most are in the form SELECT foo,bar FROM baz WHERE quux = ? ORDER BY bar LIMIT 1. The most complex statement in the lot is simply three such selects joined together with UNION ALLs. Each page hit executes at most one statement and executes it only once. I'm in a hosted environment and therefore leery of slamming their servers by doing any "stress tests" personally. Given that using prepared statements will, at minimum, double the number of database round-trips I'm making, am I better off avoiding them? Can I use PDO::MYSQL_ATTR_DIRECT_QUERY to avoid the overhead of multiple database trips while retaining the benefit of parametrization and injection defense? Or do the binary calls used by the prepared statement API perform well enough compared to executing non-prepared queries that I shouldn't worry about it? EDIT: Thanks for all the good advice, folks. This is one where I wish I could mark more than one answer as "accepted" — lots of different perspectives. Ultimately, though, I have to give rick his due… without his answer I would have blissfully gone off and done the completely Wrong Thing even after following everyone's advice. :-) Emulated prepared statements it is!

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• Graph-structured databases and Php

  - by stagas

  I want to use a graph database using php. Can you point out some resources on where to get started? Is there any example code / tutorial out there? Or are there any other methods of storing data that relate to each other in totally random/abstract situations? - Very abstract example of the relations needed: John relates to Mary, both relate to School, John is Tall, Mary is Short, John has Blue Eyes, Mary has Green Eyes, query I want is which people are related to 'Short people that have Green Eyes and go to School' - answer John - Another example: TrackA -> ArtistA -> ArtistB -> AlbumA -----> [ label ] -> AlbumB -----> [ A ] -> TrackA:Remix -> Genre:House -> [ Album ] -----> [ label ] TrackB -> [ C ] [ B ] Example queries: Which Genre is TrackB closer to? answer: House - because it's related to Album C, which is related to TrackA and is related to Genre:House Get all Genre:House related albums of Label A : result: AlbumA, AlbumB - because they both have TrackA which is related to Genre:House - It is possible in MySQL but it would require a fixed set of attributes/columns for each item and a complex non-flexible query, instead I need every attribute to be an item by itself and instead of 'belonging' to something, to be 'related' to something.

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