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  • When using SQL Compact on Windows Mobile, do you store the sdf file on a storage card?

    - by Michal Drozdowicz
    Having had some Sql Compact db corruption issues in the past and gone through the article on these, I got the idea that storing the database sdf file on a storage card significantly increases the risk of data loss due to db corruption. Do you store the sdf file on a storage card? Have you had any issues caused by it? What should I pay attention to when recommending a particular brand or model of an SD card wrt the stability and security for use with SQL Compact?

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  • Python module being reloaded for each request with django and mod_wsgi

    - by Vishal
    I have a variable in init of a module which get loaded from the database and takes about 15 seconds. For django development server everything is working fine but looks like with apache2 and mod_wsgi the module is loaded with every request (taking 15 seconds). Any idea about this behavior? Update: I have enabled daemon mode in mod wsgi, looks like its not reloading the modules now! needs more testing and I will update.

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  • UUID collision risk using different algorithms

    - by Diego Jancic
    Hi Guys, I have a database where 2 (or maybe 3 or 4) different applications are inserting information. The new information has IDs of the type GUID/UUID, but each application is using a different algorithm to generate the IDs. For example, one is using the NHibernate's "guid.comb", other is using the SQLServer's NEWID(), other might want to use .NET's Guid.NewGuid() implementation. Is there an above normal risk of ID collision or duplicates? Thanks!

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  • Mapping One-to-One subclass in Fluent NHibernate

    - by Mike C.
    I have the following database structure: Event table Id - Guid (PK) Name - NVarChar Description - NVarChar SpecialEvent table Id - Guid (PK) StartDate - DateTime EndDate - DateTime I have an abstract Event class, and a SpecialEvent class that inherits from it. Eventually I will have a RecurringEvent class which will inherit from the Event class also. I'd like to map the SpecialEvent class while preserving a one-to-one relationship mapped with the Ids, if possible. Can anybody point me in the correct direction? Thanks!

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  • Update thousands of records in a DataSet to SQL Server

    - by MSIL
    I have half a million records in a data set of which 50,000 are updated. Now I need to commit the updated records back to the SQL Server 2005 Database. What is the best and efficient way to do this considering the fact that such updates could be frequent (though concurrency is not an issue but performance is)

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  • php mysql timestamp

    - by user342391
    I need to track the date and time a user was created in my mysql database. I have column called 'created' and the data type as TIMESTAMP. The problem is that when a user changes their password or other information the TIMESTAMP value changes. How can I set this to not change????

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  • NHibernate unable to create SessionFactory

    - by Tyler
    I'm having a bit of trouble setting up NHibernate, and I'm not too sure what the problem is exactly. I'm attempting to save a domain object to the database (Oracle 10g XE). However, I'm getting a TypeInitializationException while trying to create the ISessionFactory. Here is what my hibernate.cfg.xml looks like: <?xml version="1.0" encoding="utf-8"?> <hibernate-configuration xmlns="urn:nhibernate-configuration-2.2" > <session-factory name="MyProject.DataAccess"> <property name="connection.driver_class">NHibernate.Driver.OracleClientDriver</property> <property name="connection.connection_string"> User ID=myid;Password=mypassword;Data Source=localhost </property> <property name="show_sql">true</property> <property name="dialect">NHibernate.Dialect.OracleDialect</property> <property name="proxyfactory.factory_class">NHibernate.ByteCode.LinFu.ProxyFactoryFactory, NHibernate.ByteCode.LinFu</property> <mapping resource="MyProject/Domain/User.hbm.xml"/> </session-factory> </hibernate-configuration> I created a DAO which I will use to persist domain objects to the database. The DAO uses a HibernateUtil class that creates the SessionFactory. Both classes are in the DataAccess namespace along with the Hibernate configuration. This is where the exception is occuring. Here's that class: public class HibernateUtil { private static ISessionFactory SessionFactory = BuildSessionFactory(); private static ISessionFactory BuildSessionFactory() { try { // This seems to be where the problem occurs return new Configuration().Configure().BuildSessionFactory(); } catch (TypeInitializationException ex) { Console.WriteLine("Initial SessionFactory creation failed." + ex); throw new Exception("Unable to create SessionFactory."); } } public static ISessionFactory GetSessionFactory() { return SessionFactory; } } The DataAccess namespace references the NHibernate DLLs. This is virtually the same setup I've used with Hibernate in Java, so I'm not entirely sure what I'm doing wrong here. Any ideas? Edit The innermost exception is the following: "Could not find file 'C:\Users\Tyler\Documents\Visual Studio 2010\Projects\MyProject\MyProject\ConsoleApplication\bin\Debug\hibernate.cfg.xml'." ConsoleApplication contains the entry point where I've created a User object and am trying to persist it with my DAO. Why is it looking for the configuration file there? The actual persisting takes place in the DAO, which is in DataAccess. Also, when I add the configuration file to ConsoleApplication, it still does not find it.

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  • Rails: Easiest way to provide file downloads?

    - by Schroedinger
    G'day guys, currently have almost finished writing a rails application that allows a CSV download of the database. This is generated when the index is first viewed. Is there an easy way to insert a link to a helper that returns a CSV document? That is to say is it easy to insert links to helpers? This would make a lot of problems I've been having much easier

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  • Necessary rights to be able to add a column with ALTER TABLE ADD column_name

    - by Sorin Comanescu
    Hi, Could somebody point out the necessary rights to do something like ALTER TABLE myTable ADD myColumn int NOT NULL CONSTRAINT [Constraint_name] DEFAULT ((0)) ? I assumed grant alter on myTable to [user] was enough but I'm getting the error message The UPDATE permission was denied on the object 'myTable', database 'x', schema 'dbo'. Could UPDATE rights be needed because of the DEFAULT constraint? Thanks.

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  • Changing Passwords Over Multiple Servers and Services

    - by tesmar
    Hi all, I am looking to automate the changing of passwords across multiple services and servers. For example: I want to change the root paassword to all of my web servers at once. I am thinking of writing a ruby script, but have you guys run across anything already written? If so, would that also give me the ability to change other system passwords like Database passwords and SVN passwords.

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  • Programmatically import CSV data to Access

    - by FrustratedWithFormsDesigner
    I have an Access database and the source of data comes from generated CSV files. I'd like to have an easy way for the users to simply select the data file and import it. Import should append the existing data to the data already in the data table. Is there a way in Access to create a file selector and import using saved CSV import settings that are already in the file?

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  • Date difference in minutes

    - by zurna
    I have DateFirstStarted and DateEnded fields in the database. Date values are recorded as DateFirstStarted 04/13/2010 07:00:00.000 PM DateEnded 04/13/2010 09:00:00.000 PM How do I print minute difference between two dates. I tried the following code but it returned something like 999343 Clock = DateDiff("m", objLiveCommentary("DateFirstStarted"), objLiveCommentary("DateEnded"))

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  • core data and paging

    - by Joo Park
    I have a database of 50,000 records. I'm using core data to fetch records from a search. A search could return 1000 records easily. What is needed to page through these records using core data and uitableview? I would like to show 100 records at a time and have 'load more' button after viewing 100 records.

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  • Is this postgres function cost efficient or still have to clean

    - by kiranking
    There are two tables in postgres db. english_all and english_glob First table contains words like international,confidential,booting,cooler ...etc I have written the function to get the words from english_all then perform for loop for each word to get word list which are not inserted in anglish_glob table. Word list is like I In Int Inte Inter .. b bo boo boot .. c co coo cool etc.. for some reason zwnj(zero-width non-joiner) is added during insertion to english_all table. But in function I am removing that character with regexp_replace. Postgres function for_loop_test is taking two parameter min and max based on that I am selecting words from english_all table. function code is like DECLARE inMinLength ALIAS FOR $1; inMaxLength ALIAS FOR $2; mviews RECORD; outenglishListRow english_word_list;--custom data type eng_id,english_text BEGIN FOR mviews IN SELECT id,english_all_text FROM english_all where wlength between inMinLength and inMaxLength ORDER BY english_all_text limit 30 LOOP FOR i IN 1..char_length(regexp_replace(mviews.english_all_text,'(?)$','')) LOOP FOR outenglishListRow IN SELECT distinct on (regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','')) mviews.id, regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') where regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') not in(select english_glob.english_text from english_glob where i=english_glob.wlength) order by regexp_replace((substring(mviews.english_all_text from 1 for i)),'(?)$','') LOOP RETURN NEXT outenglishListRow; END LOOP; END LOOP; END LOOP; END; Once I get the word list I will insert that into another table english_glob. My question is is there any thing I can add to or remove from function to make it more efficient. edit Let assume english_all table have words like footer,settle,question,overflow,database,kingdom If inMinLength = 5 and inmaxLength=7 then in the outer loop footer,settle,kingdom will be selected. For above 3 words inner two loop will apply to get words like f,fo,foo,foot,foote,footer,s,se,set,sett,settl .... etc. In the final process words which are bold will be entered into english_glob with another parameter like 1 to denote it is a proper word and stored in the another filed of english_glob table. Remaining word will be stored with another parameter 0 because in the next call words which are saved in database should not be fetched again. edit2: This is a complete code CREATE TABLE english_all ( id serial NOT NULL, english_all_text text NOT NULL, wlength integer NOT NULL, CONSTRAINT english_all PRIMARY KEY (id), CONSTRAINT english_all_kan_text_uq_id UNIQUE (english_all_text) ) CREATE TABLE english_glob ( id serial NOT NULL, english_text text NOT NULL, is_prop integer default 1, CONSTRAINT english_glob PRIMARY KEY (id), CONSTRAINT english_glob_kan_text_uq_id UNIQUE (english_text) ) insert into english_all(english_text) values ('ant'),('forget'),('forgive'); on function call with parameter 3 and 6 fallowing rows should fetched a an ant f fo for forg forge forget next is insert to another table based on above row insert into english_glob(english_text,is_prop) values ('a',1),('an',1), ('ant',1),('f',0), ('fo',0),('for',1), ('forg',0),('forge',1), ('forget',1), on function call next time with parameter 3 and 7 fallowing rows should fetched.(because f,fo,for,forg are all entered in english_glob table) forgi forgiv forgive

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  • Can MySQL reasonably perform queries on billions of rows?

    - by haxney
    I am planning on storing scans from a mass spectrometer in a MySQL database and would like to know whether storing and analyzing this amount of data is remotely feasible. I know performance varies wildly depending on the environment, but I'm looking for the rough order of magnitude: will queries take 5 days or 5 milliseconds? Input format Each input file contains a single run of the spectrometer; each run is comprised of a set of scans, and each scan has an ordered array of datapoints. There is a bit of metadata, but the majority of the file is comprised of arrays 32- or 64-bit ints or floats. Host system |----------------+-------------------------------| | OS | Windows 2008 64-bit | | MySQL version | 5.5.24 (x86_64) | | CPU | 2x Xeon E5420 (8 cores total) | | RAM | 8GB | | SSD filesystem | 500 GiB | | HDD RAID | 12 TiB | |----------------+-------------------------------| There are some other services running on the server using negligible processor time. File statistics |------------------+--------------| | number of files | ~16,000 | | total size | 1.3 TiB | | min size | 0 bytes | | max size | 12 GiB | | mean | 800 MiB | | median | 500 MiB | | total datapoints | ~200 billion | |------------------+--------------| The total number of datapoints is a very rough estimate. Proposed schema I'm planning on doing things "right" (i.e. normalizing the data like crazy) and so would have a runs table, a spectra table with a foreign key to runs, and a datapoints table with a foreign key to spectra. The 200 Billion datapoint question I am going to be analyzing across multiple spectra and possibly even multiple runs, resulting in queries which could touch millions of rows. Assuming I index everything properly (which is a topic for another question) and am not trying to shuffle hundreds of MiB across the network, is it remotely plausible for MySQL to handle this? UPDATE: additional info The scan data will be coming from files in the XML-based mzML format. The meat of this format is in the <binaryDataArrayList> elements where the data is stored. Each scan produces = 2 <binaryDataArray> elements which, taken together, form a 2-dimensional (or more) array of the form [[123.456, 234.567, ...], ...]. These data are write-once, so update performance and transaction safety are not concerns. My naïve plan for a database schema is: runs table | column name | type | |-------------+-------------| | id | PRIMARY KEY | | start_time | TIMESTAMP | | name | VARCHAR | |-------------+-------------| spectra table | column name | type | |----------------+-------------| | id | PRIMARY KEY | | name | VARCHAR | | index | INT | | spectrum_type | INT | | representation | INT | | run_id | FOREIGN KEY | |----------------+-------------| datapoints table | column name | type | |-------------+-------------| | id | PRIMARY KEY | | spectrum_id | FOREIGN KEY | | mz | DOUBLE | | num_counts | DOUBLE | | index | INT | |-------------+-------------| Is this reasonable?

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  • Redirecting to another controller in Rails

    - by Vitaly
    Hi, I'm trying to redirect from one controller to another in Rails and I am getting this error: undefined method `call' for nil:NilClass The code is pretty simple (in def create method): @blog_post_comment = BlogPostComment.new(params[:blog_post_comment]) respond_to do |format| if @blog_post_comment.save flash[:notice] = 'Comment was successfully created.' redirect_to(@blog_post_comment.blog_post) else render :action => "new" end end Save goes ok, the value gets into the database. How can I work around the redirect fail?

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  • template pass by const reference

    - by 7vies
    Hi, I've looked over a few similar questions, but I'm still confused. I'm trying to figure out how to explicitly (not by compiler optimization etc) and C++03-compatible avoid copying of an object when passing it to a template function. Here is my test code: #include <iostream> using namespace std; struct C { C() { cout << "C()" << endl; } C(const C&) { cout << "C(C)" << endl; } ~C() { cout << "~C()" << endl; } }; template<class T> void f(T) { cout << "f<T>" << endl; } template<> void f(C c) { cout << "f<C>" << endl; } // (1) template<> void f(const C& c) { cout << "f<C&>" << endl; } // (2) int main() { C c; f(c); return 0; } (1) accepts the object of type C, and makes a copy. Here is the output: C() C(C) f<C> ~C() ~C() So I've tried to specialize with a const C& parameter (2) to avoid this, but this simply doesn't work (apparently the reason is explained in this question). Well, I could "pass by pointer", but that's kind of ugly. So is there some trick that would allow to do that somehow nicely? EDIT: Oh, probably I wasn't clear. I already have a templated function template<class T> void f(T) {...} But now I want to specialize this function to accept a const& to another object: template<> void f(const SpecificObject&) {...} But it only gets called if I define it as template<> void f(SpecificObject) {...}

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  • sql "Group By" and "Having"

    - by Hans Rudel
    im trying to work through some questions and im not sure how to do the following Q:Find the hard drive sizes that are equal among two or more PCs. its q15 on this site http://www.sql-ex.ru/learn_exercises.php#answer_ref The database scheme consists of four tables: Product(maker, model, type) PC(code, model, speed, ram, hd, cd, price) Laptop(code, model, speed, ram, hd, screen, price) Printer(code, model, color, type, price) any pointers would be appreciated.

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  • File transfer through SQL Server connection

    - by wasim
    I have a text file sitting on client machine and want to move it to the database server (MS SQL 2008) but I don't have any access to the server except through the SQL Server client. Can I transfer this file to the server using SQL client connection?

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  • Off the shelf Php User Forum

    - by dta
    I have a pre-existing user database on my site. Now, I want to install a PHP-Based Forum on my site which works with already existing user table. Also, I would like it to be as lightweight as possible -- in terms of features as well as bandwidth consumption Please suggest some.. Thanks.

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