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• Using an ORM with a database that has no defined relationships?

  - by Ahmad

  Consider a database(MSSQL 2005) that consists of 100+ tables which have primary keys defined to a certain degree. There are 'relationships' between tables, however these are not enforced with foreign key constraints. Consider the following simplified example of typical types of tables I am dealing with. The are clear relations between the User and City and Province tables. However, they key issues is the inconsistent data types in the tables and naming conventions. User: UserRowId [int] PK Name [varchar(50)] CityId [smallint] ProvinceRowId [bigint] City: CityRowId [bigint] PK CityDescription [varchar(100)] Province: ProvinceId [int] PK ProvinceDesc [varchar(50)] I am considering a rewrite of the application (in ASP.net MVC) that uses this data source as is similar in design to MVC storefront. However I am going through a proof of concept phase and this is one of the stumbling blocks I have come across. What are my options in terms of ORM choice that can be easily used and why? Should I even be considering an ORM? (The reason I ask this is that most explanations and tutorials all work with relatively cleanly designed existing databases, or newly created ones when compared to mine. I am thus having a very hard time trying to find a way forward with this problem) There is a huge amount of existing SQL queries, would a datamappper(eg IBatis.net) be more suitable since we could easily modify them to work and reuse the investment already made? I have found this question on SO which indicates to me that an ORM can be used - however I get the impression that this a question of mapping? Note: at the moment, the object model is not clearly defined as it was non-existent. The existing system pretty much did almost everything in SQL or consisted of overly complicated, and numerous queries to complete fucntionality. I am pretty much a noob and have zero experience around ORMs and MVC - so this an awesome learning curve I am on.

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• Looking to reimplement build toolchain from bash/grep/sed/awk/(auto)make/configure to something more

  - by wash

  I currently maintain a few boxes that house a loosely related cornucopia of coding projects, databases and repositories (ranging from a homebrew *nix distro to my class notes), maintained by myself and a few equally pasty-skinned nerdy friends (all of said cornucopia is stored in SVN). The vast majority of our code is in C/C++/assembly (a few utilities are in python/perl/php, we're not big java fans), compiled in gcc. Our build toolchain typically consists of a hodgepodge of make, bash, grep, sed and awk. Recent discovery of a Makefile nearly as long as the program it builds (as well as everyone's general anxiety with my cryptic sed and awking) has motivated me to seek a less painful build system. Currently, the strongest candidate I've come across is Boost Build/Bjam as a replacement for GNU make and python as a replacement for our build-related bash scripts. Are there any other C/C++/asm build systems out there worth looking into? I've browsed through a number of make alternatives, but I haven't found any that are developed by names I know aside from Boost's. (I should note that an ability to easily extract information from svn commandline tools such as svnversion is important, as well as enough flexibility to configure for builds of asm projects as easily as c/c++ projects)

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• Setting up relations/mappings for a SQLAlchemy many-to-many database

  - by Brent Ramerth

  I'm new to SQLAlchemy and relational databases, and I'm trying to set up a model for an annotated lexicon. I want to support an arbitrary number of key-value annotations for the words which can be added or removed at runtime. Since there will be a lot of repetition in the names of the keys, I don't want to use this solution directly, although the code is similar. My design has word objects and property objects. The words and properties are stored in separate tables with a property_values table that links the two. Here's the code: from sqlalchemy import Column, Integer, String, Table, create_engine from sqlalchemy import MetaData, ForeignKey from sqlalchemy.orm import relation, mapper, sessionmaker from sqlalchemy.ext.declarative import declarative_base engine = create_engine('sqlite:///test.db', echo=True) meta = MetaData(bind=engine) property_values = Table('property_values', meta, Column('word_id', Integer, ForeignKey('words.id')), Column('property_id', Integer, ForeignKey('properties.id')), Column('value', String(20)) ) words = Table('words', meta, Column('id', Integer, primary_key=True), Column('name', String(20)), Column('freq', Integer) ) properties = Table('properties', meta, Column('id', Integer, primary_key=True), Column('name', String(20), nullable=False, unique=True) ) meta.create_all() class Word(object): def __init__(self, name, freq=1): self.name = name self.freq = freq class Property(object): def __init__(self, name): self.name = name mapper(Property, properties) Now I'd like to be able to do the following: Session = sessionmaker(bind=engine) s = Session() word = Word('foo', 42) word['bar'] = 'yes' # or word.bar = 'yes' ? s.add(word) s.commit() Ideally this should add 1|foo|42 to the words table, add 1|bar to the properties table, and add 1|1|yes to the property_values table. However, I don't have the right mappings and relations in place to make this happen. I get the sense from reading the documentation at http://www.sqlalchemy.org/docs/05/mappers.html#association-pattern that I want to use an association proxy or something of that sort here, but the syntax is unclear to me. I experimented with this: mapper(Word, words, properties={ 'properties': relation(Property, secondary=property_values) }) but this mapper only fills in the foreign key values, and I need to fill in the other value as well. Any assistance would be greatly appreciated.

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• Create new or update existing entity at one go with JPA

  - by Alex R

  A have a JPA entity that has timestamp field and is distinguished by a complex identifier field. What I need is to update timestamp in an entity that has already been stored, otherwise create and store new entity with the current timestamp. As it turns out the task is not as simple as it seems from the first sight. The problem is that in concurrent environment I get nasty "Unique index or primary key violation" exception. Here's my code: // Load existing entity, if any. Entity e = entityManager.find(Entity.class, id); if (e == null) { // Could not find entity with the specified id in the database, so create new one. e = entityManager.merge(new Entity(id)); } // Set current time... e.setTimestamp(new Date()); // ...and finally save entity. entityManager.flush(); Please note that in this example entity identifier is not generated on insert, it is known in advance. When two or more of threads run this block of code in parallel, they may simultaneously get null from entityManager.find(Entity.class, id) method call, so they will attempt to save two or more entities at the same time, with the same identifier resulting in error. I think that there are few solutions to the problem. Sure I could synchronize this code block with a global lock to prevent concurrent access to the database, but would it be the most efficient way? Some databases support very handy MERGE statement that updates existing or creates new row if none exists. But I doubt that OpenJPA (JPA implementation of my choice) supports it. Event if JPA does not support SQL MERGE, I can always fall back to plain old JDBC and do whatever I want with the database. But I don't want to leave comfortable API and mess with hairy JDBC+SQL combination. There is a magic trick to fix it using standard JPA API only, but I don't know it yet. Please help.

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• Relational MySQL - fetched properties?

  - by Kelso.b

  I'm currently using the following PHP code: // Get all subordinates $subords = array(); $supervisorID = $this->session->userdata('supervisor_id'); $result = $this->db->query(sprintf("SELECT * FROM users WHERE supervisor_id=%d AND id!=%d",$supervisorID, $supervisorID)); $user_list_query = 'user_id='.$supervisorID; foreach($result->result() as $user){ $user_list_query .= ' OR user_id='.$user->id; $subords[$user->id] = $user; } // Get Submissions $submissionsResult = $this->db->query(sprintf("SELECT * FROM submissions WHERE %s", $user_list_query)); $submissions = array(); foreach($submissionsResult->result() as $submission){ $entriesResult = $this->db->query(sprintf("SELECT * FROM submittedentries WHERE timestamp=%d", $submission->timestamp)); $entries = array(); foreach($entriesResult->result() as $entries) $entries[] = $entry; $submissions[] = array( 'user' => $subords[$submission->user_id], 'entries' => $entries ); $entriesResult->free_result(); } Basically I'm getting a list of users that are subordinates of a given supervisor_id (every user entry has a supervisor_id field), then grabbing entries belonging to any of those users. I can't help but think there is a more elegant way of doing this, like SELECT FROM tablename where user->supervisor_id=2222 Is there something like this with PHP/MySQL? Should probably learn relational databases properly sometime. :(

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• Online file storage similar to Amazon S3

  - by Joel G

  I am looking to code a file storage application in perl similar to amazon s3. I already have a amazon s3 clone that I found online called parkplace but its in ruby and is old also isn't built for high loads. I am not really sure what modules and programs I should use so id like some help picking them out. My requirements are listed below (yes I know there are lots but I could start simple then add more once I get it going): Easy API implementation for client side apps. (maybe RESTful but extras like mkdir and cp (?) Centralized database server for the USERDB (maybe PostgreSQL (?). Logging of all connections, bandwidth used, well pretty much everything to a centralized server (maybe PostgreSQL again (?). Easy server side configuration (config file(s) stored on the servers). Web based control panel for admin(s) and user(s) to show logs. (could work just running queries from the databases) Fast High Uptime Low memory usage Some sort of load distribution/load balancer (maybe a dns based or pound or perlbal or something else (?). Maybe a cache of some sort (memcached or parlbal or something else (?). Thanks in advance

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• Web development scheme for staging and production servers using Git Push

  - by ServAce85

  I am using git to manage a dynamic website (PHP + MySQL) and I want to send my files from my localhost to my staging and development servers in the most efficient and hassle-free way. I am currently convinced that the best way for me to approach this problem is to use this git branching model to organize my local git repo. From there, I will use the release branches to push to my staging server for testing. Once I am happy that the release code works on the staging server, I can then merge with my master branch and push that to my production server. Pushing to Staging Server: As noted in many introductory git posts, I could run into problems pushing into a non-bare repo, so, as suggested in this response, I plan to push the release branch to a bare repo on the server and have a post-receive hook that clones the bare repo to a non-bare repo that also acts as the web-hosted directory. Pushing to Production Server: Here's my newest source of confusion... In the response that I cited above, it made me curious as to why @Paul states that it's a completely different story when pushing to a live, development server. I guess I don't see the problem. Would it be safe and hassle-free to follow the same steps as above, but for the master branch? Where are the potential pit-falls? Config Files: With respect to configuration files that are unique to each environment (.htaccess, config.php, etc), it seems simplest to .gitignore each of those files in their respective repos on their respective servers. Can you see anything immediately wrong with this? Better solutions? Accessing Data: Finally, as I initially stated, the site uses MySQL databases to store data. How would you suggest I access that data (for testing purposes) from the staging server and localhost? I realize that I may have asked way too many questions for a single post, but since they're all related to the best way to set up this development scheme, I thought it was necessary.

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• Update SQL Server 2000 to SQL Server 2008: Benefits please?

  - by Ciaran Archer

  Hi there I'm looking for the benefits of upgrading from SQL Server 2000 to 2008. I was wondering: What database features can we leverage with 2008 that we can't now? What new TSQL features can we look forward to using? What performance benefits can we expect to see? What else will make management go for it? And the converse: What problems can we expect to encounter? What other problems have people found when migrating? Why fix something that isn't (technically) broken? We work in a Java shop, so any .NET / CLR stuff won't rock our world. We also use Eclipse as our main development so any integration with Visual Studio won't be a plus. We do use SQL Server Management Studio however. Some background: Our main database machine is a 32bit Dell Intel Xeon MP CPU 2.0GHz, 40MB of RAM with Physical Address Extension running Windows Server 2003 Enterprise Edition. We will not be changing our hardware. Our databases in total are under a TB with some having more than 200 tables. But they are busy and during busy times we see 60-80% CPU utilisation. Apart form the fact that SQL Server 2000 is coming close to end of life, why should we upgrade? Any and all contributions are appreciated!

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• Unattended Install of SQL Server 2005 Express with LOCAL Server InstanceName

  - by Jeff

  I'm creating an install package using InnoSetup and installing SQL Server 2005 Express. Here's the code below that appears in my RUN section: Filename: "{app}\SQL Server 2005 Express\SQLEXPR.exe" ; Parameters: "-q /norebootchk /qn reboot=ReallySuppress addlocal=all INSTANCENAME=(LOCAL) SCCCHECKLEVEL=IncompatibleComponents:1;MDAC25Version:0 ERRORREPORTING=2 SQLAUTOSTART=1 SAPWD=passwordhere SECURITYMODE=SQL"; WorkingDir: {app}\SQL Server 2005 Express; StatusMsg: Installing Microsoft SQL Server 2005 Express... Please Wait...;Check:SQLVerifyInstall What I'm trying to accomplish is have the SQL Server package install but only have the instance name itself reference the name of the machine name and nothing more. What I'm receiving instead is a named instance instead of local such as MachineName\SQLEXPRESS which is not what I want to receive. I need a local instance instead of a named instance due to the way my code is written to be able to install and talk with the databases in question. I would change it, trust me, were it not the fact that this install package is a replacement to a previous package that used the MSDE installer. I have to be able to support both through code. Any suggestions are welcome but a clear and concise method to get the installer to quietly install using only the machine name is my main goal. Thanks for the help and support!

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• Is dependency injection only for service type objects and singletons? (and NOT for gui?)

  - by sensui

  I'm currently experimenting with the Google's guice inversion of control container. I previously had singletons for just about any service (database, active directory) my application used. Now I refactored the code: all the dependencies are given as parameters to constructors. So far, so good. Now the hardest part is with the graphical user interface. I face this problem: I have a table (JTable) of products wrapped in an ProductFrame. I give the dependencies as parameters (EditProductDialog). @Inject public ProductFrame(EditProductDialog editProductDialog) { // ... } // ... @Inject public EditProductDialog(DBProductController productController, Product product) { // ... } The problem is that guice can't know what Product I have selected in the table, so it can't know what to inject in the EditProductDialog. Dependency Injection is pretty viral (if I modify one class to use dependency injection I also need to modify all the other classes it interacts with) so my question is should I directly instantiate EditProductDialog? But then I would have to pass manually the DBProductController to the EditProductDialog and I will also need to pass it to the ProductFrame and all this boils down to not using dependency injection at all. Or is my design flawed and because of that I can't really adapt the project to dependecy injection? Give me some examples of how you used dependency injection with the graphical user interface. All the examples found on the Internet are really simple examples where you use some services (mostly databases) with dependency injection.

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• Making a database backup to SDCard on Android

  - by Pentium10

  I am using the below code to write a backup copy to SDCard and I get java.io.IOException: Parent directory of file is not writable: /sdcard/mydbfile.db private class ExportDatabaseFileTask extends AsyncTask<String, Void, Boolean> { private final ProgressDialog dialog = new ProgressDialog(ctx); // can use UI thread here protected void onPreExecute() { this.dialog.setMessage("Exporting database..."); this.dialog.show(); } // automatically done on worker thread (separate from UI thread) protected Boolean doInBackground(final String... args) { File dbFile = new File(Environment.getDataDirectory() + "/data/com.mypkg/databases/mydbfile.db"); File exportDir = new File(Environment.getExternalStorageDirectory(), ""); if (!exportDir.exists()) { exportDir.mkdirs(); } File file = new File(exportDir, dbFile.getName()); try { file.createNewFile(); this.copyFile(dbFile, file); return true; } catch (IOException e) { Log.e("mypck", e.getMessage(), e); return false; } } // can use UI thread here protected void onPostExecute(final Boolean success) { if (this.dialog.isShowing()) { this.dialog.dismiss(); } if (success) { Toast.makeText(ctx, "Export successful!", Toast.LENGTH_SHORT).show(); } else { Toast.makeText(ctx, "Export failed", Toast.LENGTH_SHORT).show(); } } void copyFile(File src, File dst) throws IOException { FileChannel inChannel = new FileInputStream(src).getChannel(); FileChannel outChannel = new FileOutputStream(dst).getChannel(); try { inChannel.transferTo(0, inChannel.size(), outChannel); } finally { if (inChannel != null) inChannel.close(); if (outChannel != null) outChannel.close(); } } }

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• Building out a well-structured service layer

  - by Chris Stewart

  First, I want to say that it has been awhile since I've gotten into the kind of detail I am at currently. Lately, I've been very much in the SharePoint world and my entire thought process was focused there for quite some time. I'm very glad to be creating databases again, writing "lower level" code to deal with data access, and so forth. I'm working on a very simple web application and taking the opportunity to reacquaint myself with the way I used to structure my projects and various layers of code. For instance, I might have created something like this the last time I went about building something basic from scratch: - MyProject/ -- Domain/ --- Impl/ ---- Person -- Model/ --- IPersonRepository --- Impl/ ---- PersonRepository : IPersonRepository -- Services --- IPersonService --- Impl/ ---- PersonService : IPersonService That would have been the project I did the real work in, and then referenced in the ASP.NET project. My approach was very much inspired by what I saw from the CodeCampServer project as at that time ASP.NET MVC was still very new and it was the only open project I could find actively being developed, and by solid people at that. What ways are you going about structuring your projects and code, when it comes to a general problem you're working on? Certainly various problems can put constraints on this, but assume it's a basic problem without specific needs that affect the structure and layout of your code.

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• multi-shop orders table and sequential order numbers based on shop

  - by imanc

  Hey, I am looking at building a shop solution that needs to be scalable. Currently it retrieves 1-2000 orders on average per day across multiple country based shops (e.g. uk, us, de, dk, es etc.) but this order could be 10x this amount in two years. I am looking at either using separate country-shop databases to store the orders tables, or looking to combine all into one order table. If all orders exist in one table with a global ID (auto num) and country ID (e.g uk,de,dk etc.), each countries orders would also need to have sequential ordering. So in essence, we'd have to have a global ID and a country order ID, with the country order ID being sequential for countries only, e.g. global ID = 1000, country = UK, country order ID = 1000 global ID = 1001, country = DE, country order ID = 1000 global ID = 1002, country = DE, country order ID = 1001 global ID = 1003, country = DE, country order ID = 1002 global ID = 1004, country = UK, country order ID = 1001 THe global ID would be DB generated and not something I would need to worry about. But I am thinking that I'd have to do a query to get the current country order based ID+1 to find the next sequential number. Two things concern me about this: 1) query times when the table has potentially millions of rows of data and I'm doing a read before a write, 2) the potential for ID number clashes due to simultaneous writes/reads. With a MyISAM table the entire table could be locked whilst the last country order + 1 is retrieved, to prevent ID number clashes. I am wondering if anyone knows of a more elegant solution? Cheers, imanc

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• Way to store a large dictionary with low memory footprint + fast lookups (on Android)

  - by BobbyJim

  I'm developing an android word game app that needs a large (~250,000 word dictionary) available. I need: reasonably fast look ups e.g. constant time preferable, need to do maybe 200 lookups a second on occasion to solve a word puzzle and maybe 20 lookups within 0.2 second more often to check words the user just spelled. EDIT: Lookups are typically asking "Is in the dictionary?". I'd like to support up to two wildcards in the word as well, but this is easy enough by just generating all possible letters the wildcards could have been and checking the generated words (i.e. 26 * 26 lookups for a word with two wildcards). as it's a mobile app, using as little memory as possible and requiring only a small initial download for the dictionary data is top priority. My first naive attempts used Java's HashMap class, which caused an out of memory exception. I've looked into using the SQL lite databases available on android, but this seems like overkill. What's a good way to do what I need?

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• Problems with display of UTF-8 encoded content from a DB

  - by LookUp Webmaster

  Dear members of the Stackoverflow community, We are developing a web application using the Zend Framework, and we are facing some encoding issues that we hope you might help us solve. The situation goes something like this: There are certain tables on a MySQL database that need to be displayed as html. Because the site is designed using the Spanish language, the database contains some characters like "á" or "ñ". Our internal policy is to set all the encodings as UTF-8, including all the databases and the tables. The problem is, that when we retrieve the content from the DB, some characters are displayed as question marks. We are out of ideas. These are all the things that we have already tried and double-checked: 1. The SQL file from which we load all the data is properly UTF-8 encoded. 2. The SQL is loaded through phpmyadmin (which is configured as UTF-8), and the resulting tables are displayed properly. 3. The netbeans environment used for coding is also set as UTF-8. The weird thing is that all the content that is hard-coded either as php or html is displayed properly. Only the values that are extracted from the database have issues. Any ideas? Thank you very much.

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• Sharepoint user details not visible to other users

  - by richardoz

  I am managing a SharePoint site that uses Form Based Authentication. We have several generic lists, document libraries and active task lists that users can create update and delete. Users can use the people pickers to select/search for everyone. But the users cannot see other users names, email addresses etc. in display lists or the people pickers. If I log in as the site collection administrator, I can see everyones details. So I know the data is available. Updated details on this problem (non-administrators) SharePoint users cannot see other users information. Example: User A assigns a task to user B. User A creates a new task and uses the people picker to find user B. User B is only visible by the login name “bname” and any information about user B is not visible or searchable within the people picker. Once user B is assigned the task, user A no longer sees the name in the task list – even though user A created it. No modified by, created by, assigned to or owner field data is visible to non-administrator users. Facts: Extranet site is configured to use Forms Based Authentication. Intranet uses windows based authentication Users of both the intranet and extranet have the same problem All databases are local The site uses SSRS integration SharePoint WSS on Windows 2003 Std -- After activating the verbose logging it looks like SharePoint is definately asking SQL server for only the user info for the currently logged in user: SELECT TOP 6 /lots-of-columns/ FROM UserData INNER MERGE JOIN Docs AS t1 ON ( 1 = 1 AND UserData.[tp_RowOrdinal] = 0 AND t1.SiteId = UserData.tp_SiteId AND t1.SiteId = @L2 AND t1.DirName = UserData.tp_DirName AND t1.LeafName = UserData.tp_LeafName AND t1.Level = UserData.tp_Level AND t1.IsCurrentVersion = 1 AND (1 = 1) ) LEFT OUTER JOIN AllUserData AS t2 ON ( UserData.[tp_Author]=t2.[tp_ID] AND UserData.[tp_RowOrdinal] = 0 AND t2.[tp_RowOrdinal] = 0 AND ( (t2.tp_IsCurrent = 1) ) AND t2.[tp_CalculatedVersion] = 0 AND t2.[tp_DeleteTransactionId] = 0x AND t2.tp_ListId = @L3 AND UserData.tp_ListId = @L4 AND t2.[tp_Author]=162 /* this is the currently logged in user */ ) WHERE (UserData.tp_IsCurrent = 1) AND UserData.tp_SiteId=@L2 AND (UserData.tp_DirName=@DN) AND UserData.tp_RowOrdinal=0 AND ( ( (UserData.[datetime1] IS NULL ) OR (UserData.[datetime1] = @L5DTP) ) AND t1.SiteId=@L2 AND (t1.DirName=@DN) ) ORDER BY UserData.[tp_Modified] Desc, UserData.[tp_ID] Asc Again, any ideas would be appreciated.

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• What happens to existing workspaces after upgrading to TFS 2010

  - by e-mre

  Hi, I was looking for some insight about what happens to existing workspaces and files that are already checked-out on people, after an upgrade to TFS2010. Surprisingly enough I can not find any satisfactory information on this. (I am talking about upgrading on new hardware by the way. Fresh TFS instance, upgraded databases) I've checked TFS Installation guide, I searched through the web, all I could find is upgrade scenarios for the server side. Nobody even mentions what happens to source control clients. I've created a virtual machine to test the upgrade process, The upgrade was successful and all my files and workspaces exist in the new server too. The problem is: The new TFS installation has a new instanceID. When I redirected on the clients to the new server, the client seemed unable to match files and file states in the workspace with the ones on the new server. This makes me wonder if it will be possible to keep working after the production upgrade. As I mentioned above I can not find anything on this, it would be great if anyone could point me to some paper or blog post about this. Thanks in advance...

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• How to use MySQL geospatial extensions with spherical geometries

  - by Joshua

  Hi Everyone, I would like to store thousands of latitude/longitude points in a MySQL db. I was successful at setting up the tables and adding the data using the geospatial extensions where the column 'coord' is a Point(lat, lng). Problem: I want to quickly find the 'N' closest entries to latitude 'X' degrees and longitude 'Y' degrees. Since the Distance() function has not yet been implemented, I used GLength() function to calculate the distance between (X,Y) and each of the entries, sorting by ascending distance, and limiting to 'N' results. The problem is that this is not calculating shortest distance with spherical geometry. Which means if Y = 179.9 degrees, the list of closest entries will only include longitudes of starting at 179.9 and decreasing even though closer entries exist with longitudes increasing from -179.9. How does one typically handle the discontinuity in longitude when working with spherical geometries in databases? There has to be an easy solution to this, but I must just be searching for the wrong thing because I have not found anything helpful. Should I just forget the GLength() function and create my own function for calculating angular separation? If I do this, will it still be fast and take advantage of the geospatial extensions? Thanks! josh UPDATE: This is exactly what I am describing above. However, it is only for SQL Server. Apparently SQL Server has a Geometry and Geography datatypes. The geography does exactly what I need. Is there something similar in MySQL?

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• How to design data storage for partitioned tagging system?

  - by Morgan Cheng

  How to design data storage for huge tagging system (like digg or delicious)? There is already discussion about it, but it is about centralized database. Since the data is supposed to grow, we'll need to partition the data into multiple shards soon or later. So, the question turns to be: How to design data storage for partitioned tagging system? The tagging system basically has 3 tables: Item (item_id, item_content) Tag (tag_id, tag_title) TagMapping(map_id, tag_id, item_id) That works fine for finding all items for given tag and finding all tags for given item, if the table is stored in one database instance. If we need to partition the data into multiple database instances, it is not that easy. For table Item, we can partition its content with its key item_id. For table Tag, we can partition its content with its key tag_id. For example, we want to partition table Tag into K databases. We can simply choose number (tag_id % K) database to store given tag. But, how to partition table TagMapping? The TagMapping table represents the many-to-many relationship. I can only image to have duplication. That is, same content of TagMappping has two copies. One is partitioned with tag_id and the other is partitioned with item_id. In scenario to find tags for given item, we use partition with tag_id. If scenario to find items for given tag, we use partition with item_id. As a result, there is data redundancy. And, the application level should keep the consistency of all tables. It looks hard. Is there any better solution to solve this many-to-many partition problem?

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• Installer for asp.net web application

  - by Thurein

  Hi I am trying to implement a installer which is going to perform following tasks.1. Check and install .net 3.52. check and install SQL server 2008 (standard edition)3. create the databases4. create a virtual directory and deploy published resources5. Deploy SSIS and package for the datawarehousing and to run the SSAS package.Right now I am using wix, to deal with some of the task, its working for me for now, but I just want to know other options and better way to do this (is there any) .Thanks and regardsThurein I am trying to implement an installer, which I m gonna hand it to the end user as a product. Check and install .net 3.5 check and install SQL server 2008 (standard edition) create the databases create a virtual directory and deploy published resources Deploy SSIS and package for the datawarehousing and to run the SSAS package. Right now I am using wix, to deal with some of the task, it works for me, but I am just curious about other options and better ways to do this (is there any) . My main intension is, I would like to distribute my product (asp.net web application) to the end user for a trial, and end user with the limited IT knowledge could install and use that web application with in a group of user. After the end of trial period the user could ask for the activation key for further usages. Thanks Thurein

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• How Can I Find What's Causing My Transaction to Get Promoted?

  - by Damian Powell

  I have web site which serves web services (a mixture of .asmx and WCF) which is mostly using LINQ to SQL and System.Transactions. Occaisionally we see the transaction get promoted to a distributed transaction which causes problems because our web servers are isolated from our databases in such a way that it is not possible for us to use MSDTC. I have configured tracing for System.Transactions by adding the following to my web.config: <system.diagnostics> <sources> <source name="System.Transactions" switchValue="Information"> <listeners> <add name="tx" type="System.Diagnostics.XmlWriterTraceListener" initializeData="tx.log" /> </listeners> </source> </sources> </system.diagnostics> It's very interesting and shows me when the transaction is promoted, but I find that it doesn't really help be discover why. Is there an equivalent tracing mechanism for ADO.NET that will show me when connections are created, including the variables that affect pooling (user, cnn string, transaction scope)?

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• How do people handle foreign keys on clients when synchronizing to master db

  - by excsm

  Hi, I'm writing an application with offline support. i.e. browser/mobile clients sync commands to the master db every so often. I'm using uuid's on both client and server-side. When synching up to the server, the servre will return a map of local uuids (luid) to server uuids (suid). Upon receiving this map, clients updated their records suid attributes with the appropriate values. However, say a client record, e.g. a todo, has an attribute 'list_id' which holds the foreign key to the todos' list record. I use luids in foreign_keys on clients. However, when that attribute is sent over to the server, it would dirty the server db with luids rather than the suid the server is using. My current solution, is for the master server to keep a record of the mappings of luids to suids (per client id) and for each foreign key in a command, look up the suid for that particular client and use the suid instead. I'm wondering wether others have come across thus problem and if so how they have solved it? Is there a more efficient, simpler way? I took a look at this question "Synchronizing one or more databases with a master database - Foreign keys (5)" and someone seemed to suggest my current solution as one option, composite keys using suids and autoincrementing sequences and another option using -ve ids for client ids and then updating all negative ids with the suids. Both of these other options seem like a lot more work. Thanks, Saimon

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• Which MySQL Fork/Version to Pick??

  - by Drew

  As most of you know, Sun acquired MySQL (and later Oracle acquired Sun), and during these acquisitions, there were a lot of FUD in MySQL community which resulted in creation of various forks. Today we have MySQL from MySQL, Percona (XtraDB) MySQL, OurDelta MySQL, MariaDB, Drizzle to name a few. Which brings us to the source of the problem. We are in the process of upgrading our databases (hardware/software) and I would like to know which one of the forks should I go with. Each has their own set of pros/cons. We are currently using MySQL 5.0.x from MySQL/Linux on an 8-core machine. Our new hardware is a monster with 32 cores and 32GB of memory connecting to a fast NetApp Storage via FC. I would like to stick with MySQL from MySQL but I have heard horror stories on how badly MySQL 5.1 performs on many cores. I have also heard that MySQL 5.4 performs better on multi-core machines but that's still not production ready. In addition, I have also heard a lot of good things about Percona builds. This is what I know so far: MySQL 5.1 from MySQL: Reliable choice, but doesn't scale well on a big machine Percona: Scales well, good backing company. I don't have much experience with it MariaDB: Don't know much about it besides that it was founded by Original MySQL developers (including Monty) OurDelta: Don't know much Drizzle: Mostly optimized for cloud computing I would like to know what's the general notion about this problem. Which build/version should I go with? How are you guys picking your builds/versions? Thanks!

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• PHP Transferring Photos From One Oracle Database Table to Another

  - by Jonathan Swift

  I am attempting to transfer a set of photos (blobs) from one table to another across databases. I'm nearly there, except for binding the photo parameter. I have the following code: $conn_db1 = oci_pconnect('username', 'password', 'db1'); $conn_db2 = oci_pconnect('username', 'password', 'db2'); $parse_db1_select = oci_parse($conn_db1, "SELECT REF PID, BINARY_OBJECT PHOTOGRAPH FROM BLOBS"); $parse_db2_insert = oci_parse($conn_db2, "INSERT INTO PHOTOGRAPHS (PID, PHOTOGRAPH) VALUES (:pid, :photo)"); oci_execute($parse_db1_select); while ($row = oci_fetch_assoc($parse_db1_select)) { $pid = $row['PID']; $photo = $row['PHOTOGRAPH']; oci_bind_by_name($parse_db2_insert, ':pid', $pid, -1, OCI_B_INT); // This line causes an error oci_bind_by_name($parse_db_insert, ':photo', $photo, -1, OCI_B_BLOB); oci_execute($parse_db2_insert); } oci_close($db1); oci_close($db2); But I get the following error, on the error line commented above: Warning: oci_execute() [function.oci-execute]: ORA-03113: end-of-file on communication channel Process ID: 0 Session ID: 790 Serial number: 118 Does anyone know the right way to do this?

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• Best way to migrate export/import from SQL Server to oracle

  - by matao

  Hi guys! I'm faced with needing access for reporting to some data that lives in Oracle and other data that lives in a SQL Server 2000 database. For various reasons these live on different sides of a firewall. Now we're looking at doing an export/import from sql server to oracle and I'd like some advice on the best way to go about it... The procedure will need to be fully automated and run nightly, so that excludes using the SQL developer tools. I also can't make a live link between databases from our (oracle) side as the firewall is in the way. The data needs to be transformed in the process from a star schema to a de-normalised table ready for reporting. What I'm thinking about is writing a monster query for SQL Server (which I mostly have already) that will denormalise and read out the data from SQL Server into a flat file using the sql server equivalent of sqlplus as a scheduled task, dump into a Well Known Location, then on the oracle side have a cron job that copies down the file and loads it with sql loader and rebuilds indexes etc. This is all doable, but very manual. Is there one or a combination of FOSS or standard oracle/SQL Server tools that could automate this for me? the Irreducible complexity is the query on one side and building indexes on the other, but I would love to not have to write the CSV dumping detail or the SQL loader script, just say dump this view out to CSV on one side, and on the other truncate and insert into this table from CSV and not worry about mapping column names and all other arcane sqlldr voodoo... best practices? thoughts? comments? edit: I have about 50+ columns all of varying types and lengths in my dataset, which is why I'd prefer to not have to write out how to generate and map each single column...

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