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  • Is it bad to be the only person supporting software you have developed?

    - by trpt4him
    My employer has a need for a web-based application to manage and share data within the department, with approximately 50-75 possible users. I feel I have the ability to write it for them. I would likely use Python/Django with a MySQL database, so it would be open source. However, I'm the only IT person in my department (our larger organization has a separate IT support staff with which I often work, but not for web development). I want to develop this application, but if I leave in 1-2 years, and someone else has to come in after me and support it, will this be seen as a bad decision? This is assuming all the obvious points -- I will write documentation, I will comment my code, and I will strive to follow good application design principles. But will that be enough? In principle, is it acceptable for one person to develop and support an entire web application? Is this a "do first, then show and ask" kind of situation, or should I be certain it will be adopted by everyone involved first?

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  • Why did the web win the space of remote applications and X not?

    - by Martin Josefsson
    The X Window System is 25 years old, it had it's birthday yesterday (on the 15'th). As you probably are aware of, one of it's most important features is the separation of the server side and the client side in a way that neither Microsoft's, Apples or Wayland's windowing systems have. Back in the days (sorry for the ambiguous phrasing) many believed X would dominate over other ways to make windows because of this separation of server and client, allowing the application to be ran on a server somewhere else while the user clicks and types on her own computer at home. This use obviously still exists, but is marginalized at best. When we write and use programs that run on a server we almost always use the web with it's html/css/js. Why did the web win, and X not? The technologies used for the web (said html/css/js) are a mess. Combined with all the back-end-frameworks (Rails, Django and all) it really is a jungle to navigate thru. Still the web thrives with creativity and progress, while remote X apps do not.

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  • Why do I need a framework?

    - by lvictorino
    First of all I know my question may sounds idiot but I am no "beginner". In fact I work as game developer for several years now and I know some things about code :) But as this is no related to game development I am a bit lost. I am writing a big script (something about GIS) in Python, using a lot of data stored in a database. I made a first version of my script, and now, I'd like to re-design the whole thing. I read some advice about using a framework (like Django) for database queries. But as my script only "SELECT" informations I was wondering about the real benefits to use a framework. It seems that it adds a lot of complexity and useless embedded features (useless for my specific script) for the benefits that it will bring. Am I wrong? EDIT: few spec of this "script". Its purpose is to get GIS data on an enormous database (if you ever worked with openstreetmap you know what I mean ~= 200Go) and to manipulate this data in order to produce nice map images. Queries are not numerous (select streets, select avenues, select waterways, select forests... and so on for a specific area) but query results may be more than 10.000 rows. I'd like to sell this script as a service, so yes it's meant to stay.

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  • Which Language Next? Python? Ruby? [closed]

    - by Ryan Craig
    I am a beginning Webmaster (relatively), with 2+ years of php experience. I also have some java training and a bit of .net. My company is now close to redeveloping the website that I work on, which is coded primarily in php, but has some poorly-written .net in part as well (it's confusing and ill-planned, but I didn't make any of those decisions. Can anyone say action-oriented .net and JScript?). So, I'm trying to decide which language I should learn next to quickly develop a new site. I will probably just redevelop it at first in php because I'm very comfortable with it. However, I'd like to migrate in the next year to something newer and more forward-thinking. This being said, .net is out of the question a little bit. We need cheap developers who are fast and can get pages up quickly. In this part of the country, part-time .net developers are hard to find. So, we need something that will be pretty standard in the next few years, but we have some .net SOAP 1.1 APIs that we use on our actual service (separate from the corporate website), that we will need to integrate part of the site with. Developing with php and SOAP is much more difficult than doing the same thing. So, I may have to develop the API collaborative part in .net just to be easy, and then I'd like to use something else that is fast, flexible, forward thinking, and will be relatively standard and easy to find developers for. So, any ideas? Python and Django? Ruby on Rails? Another framework? Thanks for your thoughts. Sorry, I know this was long, but it's all very convoluted and confusing so I needed to be slightly long-winded.

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  • What kind of hosting do I need?

    - by Robert Smith
    I migrated this question from serverfault. Hopefully this is the appropriate place. I have been trying to answer this question but I haven't found an specific answer to my situation. As I want to pay for what I need, I thought I could get a good answer here. I have a custom made forum (rather than a built-in forum like the ones you can find in plugins, e.g. WP-Forum or phpBB type of software) in Django. I don't want to use Apache and modwsgi because it's usually very memory-hungry and I can't afford a big server. I prefer a combination of nginx and gunicorn which I think is very efficient (maybe you can also tell me what you think about that). I'm expecting to receive 10,000 to 20,000 visits each month with 15,000 to 30,000 page impressions. I have reviewed some cloud services like Amazon EC2 or Rackspace and other more traditional services (Linodo). This site won't use videos or big images and I certainly don't need a huge amount of bandwidth (200GB would be definitely too much). I need shell access so shared hosting is out of the question. What do I need to run a website like that without problems? What about RAM? 256MB would be enough (that's the amount of RAM offered by small instances in Amazon and Rackspace)? Do you know of any alternative to those I mentioned? If you need more information to provide a useful answer, please don't hesitate to ask. By the way, I was told that Linodo is not all that different to Amazon EC2 but this website is supposed to work 24/7, so I can't take advantage of Linodo's flexibility regarding creating and deleting instances. Thanks in advance.

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  • Installing datacommons from sunlight

    - by Newben
    I know strictly nothing from python and I am installing datacommons from the sunlightlabs. So I followed step by step the README.md https://github.com/sunlightlabs/datacommons First, it is said in the doc to add to the virtualenv dc_data, dc_matcchbox but I didn't find them. But I went to the final step to run ./manage.py runserver so I had the following message : (datacommons)newben@newben-VirtualBox:~/share-ubuntu/sunlightlabs-datacommons-e3ff1a3$ ./manage.py runserver fatal: Not a git repository (or any parent up to mount parent /home/mbenchoufi) Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set). Error: Can't find the file 'settings.py' in the directory containing './manage.py'. It appears you've customized things. You'll have to run django-admin.py, passing it your settings module. (If the file settings.py does indeed exist, it's causing an ImportError somehow.) In the 'sunlightlabs-datacommons-e3ff1a3' folder, I downloaded and put the files from github. By the way I didin't understand how to deal with the settings file. Could someone help me understand how to install datacommons ?

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  • Should I go with Java or Python for my next project, after using PHP for 5 years? [closed]

    - by vim
    I have a full-time PHP job and I've been working with PHP for 5 years. I'm not willing to stay within this technology stack any more. I also worked with Java for 2 year before, so for me it looks more obvious to switch back to Java. However during last 5 years I was thinking about starting my own project, and now I think I have a very good SAAS idea. I'm completely confused what technology should I use for my project. I don't want to do it in PHP, and after reading many articles about rapid prototype development it seems to me that Django is the best option. I will continue to work full time for my current employer because I need to pay my bills and will work on my project in my free time. The concern I have is should I do my project in Java or Python? To be realistic there is always a risk when you are doing your own project/start-up. If I do it in Java in the worst case scenario I believe I will be able to find a full time Java position because I already have some experience in Java + recent experience in my project. With regards to Python it looks like it is not very popular in my area and salaries are much more lower then for Java. On the other hand I have a feeling that if I chose Java it will take me a way longer to finish my project. Guys I'm completely confused and I need your advice. P.S. I have moved to London 2 years ago from another country, local guys are very welcome to share their thoughts about London's job market.

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  • Java or Python? Career/Start-up advice needed [closed]

    - by vim
    I have a full-time PHP job and I've been working with PHP for 5 years. As you can guess after spending 5 years I'm not willing to stay within this technology stack any more. I also worked with Java for 2 year before, so for me it looks more obvious to switch back to Java. However during last 5 years I was thinking about starting my own project, and now I think I have a very good SAAS idea. I'm completely confused what technology should I use for my project. I don't want to do it in PHP, and after reading many articles about rapid prototype development it seems to me that Django/Ruby is the best option. I will continue to work full time for my current employer because I need to pay my bills and will work on my project in my free time. The concern I have is should I do my project in Java or Python? To be realistic there is always a risk when you are doing your own project/start-up. If I do it in Java in the worst case scenario I believe I will be able to find a full time Java position because I already have some experience in Java + recent experience in my project. With regards to Python it looks like it is not very popular in my area and salaries are much more lower then for Java. On the other hand I have a feeling that if I chose Java it will take me a way longer to finish my project. Guys I'm completely confused and I need your advice. P.S. I have moved to London 2 years ago from another country, local guys are very welcome to share their thoughts about London's job market.

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  • Should I use heroku or should I have my own ssl? [closed]

    - by user1744649
    Base on your experience, can you please advice what will be better for me? Issue : I build applications and there are 2 major constraints. 1. ssl is needed since I used facebook api's. So, only heroku is a good option. 2. My web components tend to hit the Max_Execution_Time very often, since I pull a lot of data using the facebook api. Future possible purpose of this site : 1. Will use more apis from google, twitter, future. 2. Might request for donations. 3. Just for hobby. I have two options : 1. Create a web site in heroku itself by converting all the php components to a background worker in python using django. 2. Dont use heroku at all. Do the the complete hosting with godaddy (shared plan). And buy an ssl so that I can use fb apis etc. In this scenario, what do you suggest me to do?

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  • I am having a hard time learning Python, is it just me? [closed]

    - by Carpet
    For the past two weeks I am trying to learn Python and a framework for web development, while doing so I learned a lot but not what I was looking for. I did manage to get everything set up and running, followed tutorials, but I still have not managed to create a navigation bar and a simple template website. My goal is to create web applications (like a blog) and perhaps platforms similar to stackoverflow. In which language was stackoverflow created in? I believe that Python Django or Python Tornado (which I tried) is more for people who have learned desktop application development. It is hard for me to make sense out of the complex and fragmented system. I'm able to develop with PHP and have already created blogs and similar applications. If Python and a framework is not for me, what type of language would be for me, which languages are used for these type of platforms, I would like to develop myself? I only omitted PHP because I found it later on a bit too inheriting, and the code is hardly readable and becomes quickly cluttered, I love how readable Python code is.

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  • For what purpose I can use c++ to increase my skills?

    - by user824981
    I want to learn new things. Initially I was a PHP programmer. Then I thought it was not enough. Then I started learning Java thing. It took me 3 months to learn. Java, J2EE, Spring, Hibernte, Spring Security, Spring Roo and many design patterns MVC and stuff like AOP, DI . I never knew that before but I got the idea what J2EE. After 3 months, I just made a simple page with Registration form integrated with Spring Security. I wanted to make one complete project in it but that was too much for me and I didn't want spend more time on it as then i need to host that as well so I left that. Then I started learning Python and made few sys admin scripts and then Django and now I am finishing a complete web app in Python. Now I want to learn C++, but before that I need to find out what i can do with it. Just like I know Python is very useful because I have my own servers so I can write scripting and websites so Python is good for me. But I am confused in which areas C++ can help me. I don't want to end up like I have with Java where either I have big projects or nothing for day to day use.

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  • Using ContentProviderOperation to update and insert contacts

    - by Bogus
    Hello, I faced the problem updating/insertng contacts on Android 2.0+. There is no problem to insert a new contact when phone book is empty but when I did it 2nd time some fileds like TEL, EMAIL are doubled and tripped etc. but N, FN, ORG are ok (one copy). After getting and advice of other member this forum I updated a contact first and then ContentProviderResult[] returned uri's with null then I do an insert action and it went ok but after that I made an update and all contacts are aggregated into one - i got 1 contact insted 3 which existed in phone book. This one was damaged, the contact fields are randomly built. I set Google account. Code: ArrayList<ContentProviderOperation> ops = new ArrayList<ContentProviderOperation>(); ops.add(ContentProviderOperation.newUpdate(ContactsContract.RawContacts.CONTENT_URI) .withValue(RawContacts.AGGREGATION_MODE, RawContacts.AGGREGATION_MODE_DISABLED) .withValue(ContactsContract.RawContacts.ACCOUNT_TYPE, accountType) .withValue(ContactsContract.RawContacts.ACCOUNT_NAME, accountName) .build()); // add name ContentProviderOperation.Builder builder = ContentProviderOperation.newUpdate(ContactsContract.Data.CONTENT_URI); builder.withValueBackReference(ContactsContract.Data.RAW_CONTACT_ID, 0); builder.withValue(ContactsContract.Data.MIMETYPE, ContactsContract.CommonDataKinds.StructuredName.CONTENT_ITEM_TYPE); builder.withValue(ContactsContract.CommonDataKinds.StructuredName.PHONETIC_FAMILY_NAME, name); // phones ContentProviderOperation.Builder builder = ContentProviderOperation.newUpdate(ContactsContract.Data.CONTENT_URI); builder.withValueBackReference(ContactsContract.Data.RAW_CONTACT_ID, 0); builder.withValue(ContactsContract.Data.MIMETYPE, ContactsContract.CommonDataKinds.Phone.CONTENT_ITEM_TYPE); builder.withValue(ContactsContract.CommonDataKinds.Phone.NUMBER, phoneValue); builder.withValue(ContactsContract.CommonDataKinds.Phone.TYPE, phoneType); builder.withValue(ContactsContract.CommonDataKinds.Phone.LABEL, phoneLabel); ops.add(builder.build()); // emails ... // orgs ... try { ContentProviderResult[] result = mContentResolver.applyBatch(ContactsContract.AUTHORITY, ops); } } catch (Exception e) { Log.e(LOG_TAG, "Exception while contact updating: " + e.getMessage()); } What is wrong in this solution ? How does work aggregation engine ? I will be glad for help. Bogus

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  • OLAP Web Visualization and Reporting Recommendations

    - by Gok Demir
    I am preparing an offer for a customer. They proide weekly data to different organizations. There is huge amount data suits OLAP that needed to be visualized with charts and pivot tables on web and custom reports will be built by non-it persons (an easy gui). They will enter a date range, location which data columns to be included and generate report and optionally export the data to Excel. They currently prepare reports with MS Excel with Pivot Tables and but they need a better online tool now to show data to their customers. Tables are huge and need of drill-down functionality. My current knowledge Spring, Flex, MySql, Linux. I have some knowledge of PostgreSQL and MSSQL and Windows. What is the easiest way of doing this project. Do you think that SSRP (haven't tried yet) and ASP.NET better suits for this kind of job. Actually I prefer open source solutions. Flex have OLAP Data Grid control which do aggregation on client side. JasperServer seems promising but it seems I need enterprise version (multiple organizations and ad hoc queries). What about Modrian + Flex + PostgreSQL solution? Any previous experience will be appreciated. Yes I am confused with options.

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  • Database warehouse design: fact tables and dimension tables

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

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  • Entire Table is pushed to the next page when rendering a SSRS 2005 Report (as .pdf) in SSRS 2008

    - by Pwninstein
    I have a SSRS 2005 report that I'm rendering in SSRS 2008 as a .pdf. The report contains (among other things) a table that's very simple: header row, details, no footer, no aggregation, no grouping, keep together = false, pageBreakAtStart = false, pageBreakAtEnd = false, repeatHeaderOnNewPage = true. I resized the table to be much narrower than the body of the report just to be sure it wasn't extending beyond the bounds of the report, pushing everything down. But, no matter what I try, if some of the detail rows in that table would need to be pushed to the next page, then the ENTIRE TABLE is pushed to the next page, not just the extra rows. So my question is: Is there a workaround for this problem, is this a known issue, or is it even possible to get this 2005 report to render properly in 2008? NOTE: this is related to a question that I previously asked here, and is based on this MSDN forum post started by a coworker. This question is not the same as my previous question, as I'd like to see things work properly in with a 2005 report. If it's not possible, that would be good to know, as it would indicate that we need to upgrade one of our servers to SQL 2008. Thanks!

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  • Link Maven OSGi to Maven NetBeans Platform Project

    - by mxro
    I am using NetBeans 6.9 Beta and I would like to accomplish the following: Set up a project representing the main application using Maven (for instance "Maven Project", "Maven NetBeans Application") Ideally, the project should only contain the necessary libraries to run in Apache Felix (I would like to be able to right-click the project and select "Run in Felix") I do not want that the project contains all the NetBean Platform APIs I would prefer to implement the modules using OSGi. For instance "Maven OSGi Bundle", "Maven NetBeans Module" + OSGi These are the problems, which I have at the moment: The standard Maven archetype ("Maven NetBeans Application") seems always to select all APIs and I have not found a way to deselect APIs - in normal NetBeans Platform Applications that can be accomplished by going to the project properties and deselected the platform modules) - I guess it has something to do with the NetBeans repository (http://bits.netbeans.org/maven2)? Do I have to create another repository? When creating normal "NetBeans Module" with OSGi support, the modules contain both NetBeans Module and OSGi meta data, which is nice. But the "Maven NetBeans Modules" have only NetBeans meta data and the Maven OSGi Bundles have only OSGi meta data). I figured out how to add modules to the project by using project / new and then placing the modules in the Maven project folder. However, I do not quite know yet how I could link to modules from other locations (NetBeans uses Maven modules, which have to be in the same directory as the project?). Below some useful links for Maven + OSGi in NetBeans wiki.netbeans.org/STS_69_Maven_OSGI NetBeans Maven OSGi Test Specification platform.netbeans.org/tutorials/nbm-maven-quickstart.html NetBeans Platform Quick Start Using Maven (6.9) wiki.netbeans.org/MavenBestPractices NetBeans Maven BestPractices maven.apache.org/pom.html#Aggregation Maven Documentation Multi-Module Projects (sorry about the missing protocol but couldn't post the message otherwise)

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  • ai: Determining what tests to run to get most useful data

    - by Sai Emrys
    This is for http://cssfingerprint.com I have a system (see about page on site for details) where: I need to output a ranked list, with confidences, of categories that match a particular feature vector the binary feature vectors are a list of site IDs & whether this session detected a hit feature vectors are, for a given categorization, somewhat noisy (sites will decay out of history, and people will visit sites they don't normally visit) categories are a large, non-closed set (user IDs) my total feature space is approximately 50 million items (URLs) for any given test, I can only query approx. 0.2% of that space I can only make the decision of what to query, based on results so far, ~10-30 times, and must do so in <~100ms (though I can take much longer to do post-processing, relevant aggregation, etc) getting the AI's probability ranking of categories based on results so far is mildly expensive; ideally the decision will depend mostly on a few cheap sql queries I have training data that can say authoritatively that any two feature vectors are the same category but not that they are different (people sometimes forget their codes and use new ones, thereby making a new user id) I need an algorithm to determine what features (sites) are most likely to have a high ROI to query (i.e. to better discriminate between plausible-so-far categories [users], and to increase certainty that it's any given one). This needs to take into balance exploitation (test based on prior test data) and exploration (test stuff that's not been tested enough to find out how it performs). There's another question that deals with a priori ranking; this one is specifically about a posteriori ranking based on results gathered so far. Right now, I have little enough data that I can just always test everything that anyone else has ever gotten a hit for, but eventually that won't be the case, at which point this problem will need to be solved. I imagine that this is a fairly standard problem in AI - having a cheap heuristic for what expensive queries to make - but it wasn't covered in my AI class, so I don't actually know whether there's a standard answer. So, relevant reading that's not too math-heavy would be helpful, as well as suggestions for particular algorithms. What's a good way to approach this problem?

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  • Database warehoue design: fact tables and dimension tables

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

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  • Re-using aggregate level formulas in SQL - any good tactics?

    - by Cade Roux
    Imagine this case, but with a lot more component buckets and a lot more intermediates and outputs. Many of the intermediates are calculated at the detail level, but a few things are calculated at the aggregate level: DECLARE @Profitability AS TABLE ( Cust INT NOT NULL ,Category VARCHAR(10) NOT NULL ,Income DECIMAL(10, 2) NOT NULL ,Expense DECIMAL(10, 2) NOT NULL ) ; INSERT INTO @Profitability VALUES ( 1, 'Software', 100, 50 ) ; INSERT INTO @Profitability VALUES ( 2, 'Software', 100, 20 ) ; INSERT INTO @Profitability VALUES ( 3, 'Software', 100, 60 ) ; INSERT INTO @Profitability VALUES ( 4, 'Software', 500, 400 ) ; INSERT INTO @Profitability VALUES ( 5, 'Hardware', 1000, 550 ) ; INSERT INTO @Profitability VALUES ( 6, 'Hardware', 1000, 250 ) ; INSERT INTO @Profitability VALUES ( 7, 'Hardware', 1000, 700 ) ; INSERT INTO @Profitability VALUES ( 8, 'Hardware', 5000, 4500 ) ; SELECT Cust ,Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability GROUP BY Cust SELECT Category ,Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability GROUP BY Category SELECT Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability Notice how the same formulae have to be used at the different aggregation levels. This results in code duplication. I have thought of using UDFs (either scalar or table valued with an OUTER APPLY, since many of the final results may share intermediates which have to be calculated at the aggregate level), but in my experience the scalar and multi-statement table-valued UDFs perform very poorly. Also thought about using more dynamic SQL and applying the formulas by name, basically. Any other tricks, techniques or tactics to keeping these kinds of formulae which need to be applied at different levels in sync and/or organized?

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  • Entity Framework query

    - by carter-boater
    Hi all, I have a piece of code that I don't know how to improve it. I have two entities: EntityP and EntityC. EntityP is the parent of EntityC. It is 1 to many relationship. EntityP has a property depending on a property of all its attached EntityC. I need to load a list of EntityP with the property set correctly. So I wrote a piece of code to get the EntityP List first.It's called entityP_List. Then as I wrote below, I loop through the entityP_List and for each of them, I query the database with a "any" function which will eventually be translated to "NOT EXIST" sql query. The reason I use this is that I don't want to load all the attached entityC from database to memory, because I only need the aggregation value of their property. But the problem here is, the looping will query the databae many times, for each EntityP! So I am wondering if anybody can help me improve the code to query the database only once to get all the EntityP.IsAll_C_Complete set, without load EntityC to memory. foreach(EntityP p in entityP_List) { isAnyNotComoplete = entities.entityC.Any(c => c.IsComplete==false && c.parent.ID == p.ID); p.IsAll_C_Complete = !isAnyNotComoplete; } Thank you very much!

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  • Does query plan optimizer works well with joined/filtered table-valued functions?

    - by smoothdeveloper
    In SQLSERVER 2005, I'm using table-valued function as a convenient way to perform arbitrary aggregation on subset data from large table (passing date range or such parameters). I'm using theses inside larger queries as joined computations and I'm wondering if the query plan optimizer work well with them in every condition or if I'm better to unnest such computation in my larger queries. Does query plan optimizer unnest table-valued functions if it make sense? If it doesn't, what do you recommend to avoid code duplication that would occur by manually unnesting them? If it does, how do you identify that from the execution plan? code sample: create table dbo.customers ( [key] uniqueidentifier , constraint pk_dbo_customers primary key ([key]) ) go /* assume large amount of data */ create table dbo.point_of_sales ( [key] uniqueidentifier , customer_key uniqueidentifier , constraint pk_dbo_point_of_sales primary key ([key]) ) go create table dbo.product_ranges ( [key] uniqueidentifier , constraint pk_dbo_product_ranges primary key ([key]) ) go create table dbo.products ( [key] uniqueidentifier , product_range_key uniqueidentifier , release_date datetime , constraint pk_dbo_products primary key ([key]) , constraint fk_dbo_products_product_range_key foreign key (product_range_key) references dbo.product_ranges ([key]) ) go . /* assume large amount of data */ create table dbo.sales_history ( [key] uniqueidentifier , product_key uniqueidentifier , point_of_sale_key uniqueidentifier , accounting_date datetime , amount money , quantity int , constraint pk_dbo_sales_history primary key ([key]) , constraint fk_dbo_sales_history_product_key foreign key (product_key) references dbo.products ([key]) , constraint fk_dbo_sales_history_point_of_sale_key foreign key (point_of_sale_key) references dbo.point_of_sales ([key]) ) go create function dbo.f_sales_history_..snip.._date_range ( @accountingdatelowerbound datetime, @accountingdateupperbound datetime ) returns table as return ( select pos.customer_key , sh.product_key , sum(sh.amount) amount , sum(sh.quantity) quantity from dbo.point_of_sales pos inner join dbo.sales_history sh on sh.point_of_sale_key = pos.[key] where sh.accounting_date between @accountingdatelowerbound and @accountingdateupperbound group by pos.customer_key , sh.product_key ) go -- TODO: insert some data -- this is a table containing a selection of product ranges declare @selectedproductranges table([key] uniqueidentifier) -- this is a table containing a selection of customers declare @selectedcustomers table([key] uniqueidentifier) declare @low datetime , @up datetime -- TODO: set top query parameters . select saleshistory.customer_key , saleshistory.product_key , saleshistory.amount , saleshistory.quantity from dbo.products p inner join @selectedproductranges productrangeselection on p.product_range_key = productrangeselection.[key] inner join @selectedcustomers customerselection on 1 = 1 inner join dbo.f_sales_history_..snip.._date_range(@low, @up) saleshistory on saleshistory.product_key = p.[key] and saleshistory.customer_key = customerselection.[key] I hope the sample makes sense. Much thanks for your help!

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  • MySQL table data transformation -- how can I dis-aggregate MySQL time data?

    - by lighthouse65
    We are coding for a MySQL data warehousing application that stores descriptive data (User ID, Work ID, Machine ID, Start and End Time columns in the first table below) associated with time and production quantity data (Output and Time columns in the first table below) upon which aggregate (SUM, COUNT, AVG) functions are applied. We now wish to dis-aggregate time data for another type of analysis. Our current data table design: +---------+---------+------------+---------------------+---------------------+--------+------+ | User ID | Work ID | Machine ID | Event Start Time | Event End Time | Output | Time | +---------+---------+------------+---------------------+---------------------+--------+------+ | 080025 | ABC123 | M01 | 2008-01-24 16:19:15 | 2008-01-24 16:34:45 | 2120 | 930 | +---------+---------+------------+---------------------+---------------------+--------+------+ Reprocessing dis-aggregation that we would like to do would be to transform table content based on a granularity of minutes, rather than the current production event ("Event Start Time" and "Event End Time") granularity. The resulting reprocessing of existing table rows would look like: +---------+---------+------------+---------------------+--------+ | User ID | Work ID | Machine ID | Production Minute | Output | +---------+---------+------------+---------------------+--------+ | 080025 | ABC123 | M01 | 2010-01-24 16:19 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:20 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:21 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:22 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:23 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:24 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:25 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:26 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:27 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:28 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:29 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:30 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:31 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:22 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:33 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:34 | 133 | +---------+---------+------------+---------------------+--------+ So the reprocessing would take an existing row of data created at the granularity of production event and modify the granularity to minutes, eliminating redundant (Event End Time, Time) columns while doing so. It assumes a constant rate of production and divides output by the difference in minutes plus one to populate the new table's Output column. I know this can be done in code...but can it be done entirely in a MySQL insert statement (or otherwise entirely in MySQL)? I am thinking of a INSERT ... INTO construction but keep getting stuck. An additional complexity is that there are hundreds of machines to include in the operation so there will be multiple rows (one for each machine) for each minute of the day. Any ideas would be much appreciated. Thanks.

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  • java class creation dynamically and make it accessible across the network different jvms i.e. serial

    - by inj.rav
    Hi. I have a requirement of creating java classes dynamically and make it accessible different jvms across the network. I tried to use reflection and javassist tool,but nothing worked. Let me explain the scenario we are using Coherence distributed cache. It has a power of doing aggregation/filtering in parallel across the cluster. For example if a class has [dynamic class] has amount variable and getAmount/setAmount methods. Then if we execute COHERENCE queries, it will start process in parallel across the cluster. I tried to create classes at run time by using javassist and reflection. I am able to access it from single JVM, but when I tried to access the same class from other jvm [through coherence cluster]. I am getting exception of class not found [as remote jvm is not having idea of this class].I can over come this by creating same class dynamically on remote jvm also and access the methods. But coherence in built methods/functions are not able to find the class. could some one help me on this matter

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  • Examples of monoids/semigroups in programming

    - by jkff
    It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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  • Count rows against to SQL server (2005) table?

    - by David.Chu.ca
    I have a simple question with two options to get count of rows in a SQL server (2005). I am using VS 2005. There are two options to get the count: SELECT id FROM Table1 WHERE dt >= startDt AND dt < endDt;; I get a list of ids from above call in cache and then I get count by List.Count. Another option is SELECT COUNT(*) FROM Table1 WHERE dt >= startDt AND dt < endDt; The above call will get the count directly. The issue is that I had several cases of exceptions with the second method: timeout. What I found is that the table1 is too big with millions of data. When I used the first option, it seems OK. I am confused by the fact that Count() takes more time than getting all the rows(is that true?). Not sure if the aggregation call with Count() would cause SQL server to create temporary table or cache on server side and it would result in slow performance when table is too big? I am not sure what is the best way to get the count?

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