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  • Hibernate collection multiple types

    - by CaptainAwesomePants
    I have a class Player that contains a list of Accessory objects. There are two kinds of Accessories. SocketedAccessories have a list of SocketJewels, and MagicAccessories have a list of MagicEnchantments. At the database level, there is a players table that represents the player, and an accessories table that contains a list of accessories. Accessories have a type field that indicates whether they are socketed or magical, and the columns that are only used by one type are just left blank by entries of the other type. There are socket_jewels and magic_enchantments tables, representing the socket jewels or the magic enchantments on each accessory. I am trying to figure out the correct way to map this with Hibernate. One way would be for the player to have two lists of accessories, one for SocketedAccessories and one for MagicAccessories. That seems undesirable, though. What I want is a way to specify that player should have a field List<Accessory> accessories that contains both types of thing. Is there a way to tell Hibernate, in either hbm.xml or annotations, to do this?

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  • opengl + glew in Eclipse (for windows)

    - by echo
    I'm trying to get glew to work under eclipse (mingw) in windows. Seems as if it is extremely unusual not to use Visual Studio in this context. The install instructions for glew is simply "use the project file in build/vc6/"... The glew readme also writes: "If you wish to build GLEW from scratch (update the extension data from the net or add your own extension information), you need a Unix environment (including wget, perl, and GNU make). The extension data is regenerated from the top level source directory with: make extensions" In order to get glew to work in eclipse and windows I have to compile it in a unix environment? Is there no other way? Sure, it would probably be a learning experience to pull that off (if I were to succeed) but I feel that my time is best spent actually working on my project. And even if I did manage to crosscompile everything, would it work in anything but Visual Studio? Is the whole thing unfeasible and the best solution is to install Visual Studio? Google haven't been of much help, I feel like I am the only one that has ever attempted to do this (is there a good reason this?).

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  • Exporting de-aggregated data

    - by Ben
    I'm currently working on a data export feature for a survey application. We are using SQL2k8. We store data in a normalized format: QuestionId, RespondentId, Answer. We have a couple other tables that define what the question text is for the QuestionId and demographics for the RespondentId... Currently I'm using some dynamic SQL to generate a pivot that joins the question table to the answer table and creates an export, its working... The problem is that it seems slow and we don't have that much data (less than 50k respondents). Right now I'm thinking "why am I 'paying' to de-aggregate the data for each query? Why don't I cache that?" The data being exported is based on dynamic criteria. It could be "give me respondents that completed on x date (or range)" or "people that like blue", etc. Because of that, I think I have to cache at the respondent level, find out what respondents are being exported and then select their combined cached de-aggregated data. To me the quick and dirty fix is a totally flat table, RespondentId, Question1, Question2, etc. The problem is, we have multiple clients and that doesn't scale AND I don't want to have to maintain the flattened table as the survey changes. So I'm thinking about putting an XML column on the respondent table and caching the results of a SELECT * FROM Data FOR XML AUTO WHERE RespondentId = x. With that in place, I would then be able to get my export with filtering and XML calls into the XML column. What are you doing to export aggregated data in a flattened format (CSV, Excel, etc)? Does this approach seem ok? I worry about the cost of XML functions on larger result sets (think SELECT RespondentId, XmlCol.value('//data/question_1', 'nvarchar(50)') AS [Why is there air?], XmlCol.RinseAndRepeat)... Is there a better technology/approach for this? Thanks!

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  • How do I enable mod_deflate for PHP files?

    - by DM.
    I have a Liquid Web VPS account, I've made sure that mod_deflate is installed and running/active. I used to gzip my css and js files via PHP, as well as my PHP files themselves... However, I'm now trying to do this via mod_deflate, and it seems to work fine for all files except for PHP files. (Txt files work fine, css, js, static HTML files, just nothing that is generated via a PHP file.) How do I fix this? (I used the "Compress all content" option under "Optimize Website" in cPanel, which creates an .htaccess file in the home directory (not public_html, one level higher than that) with exactly the same text as the "compress everything except images" example on http://httpd.apache.org/docs/2.0/mod/mod_deflate.html) .htaccess file: <IfModule mod_deflate.c> SetOutputFilter DEFLATE <IfModule mod_setenvif.c> # Netscape 4.x has some problems... BrowserMatch ^Mozilla/4 gzip-only-text/html # Netscape 4.06-4.08 have some more problems BrowserMatch ^Mozilla/4\.0[678] no-gzip # MSIE masquerades as Netscape, but it is fine # BrowserMatch \bMSIE !no-gzip !gzip-only-text/html # NOTE: Due to a bug in mod_setenvif up to Apache 2.0.48 # the above regex won't work. You can use the following # workaround to get the desired effect: BrowserMatch \bMSI[E] !no-gzip !gzip-only-text/html # Don't compress images SetEnvIfNoCase Request_URI .(?:gif|jpe?g|png)$ no-gzip dont-vary </IfModule> <IfModule mod_headers.c> # Make sure proxies don't deliver the wrong content Header append Vary User-Agent env=!dont-vary </IfModule> </IfModule>

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  • Can an application affect TCP retransmits

    - by sipwiz
    I'm troubleshooting some communications issues and in the network traces I am occasionally coming across TCP sequence errors. One example I've got is: Server to Client: Seq=3174, Len=50 Client to Server: Ack=3224 Server to Client: Seq=3224, Len=50 Client to Server: Ack=3224 Server to Client: Seq=3274, Len=10 Client to Server: Ack=3224, SLE=3274, SRE=3284 Packets 4 & 5 are recorded in the trace (which is from a router in between the client and server) at almost exactly the same time so they most likely crossed in transit. The TCP session has got out of sync with the client missing the last two transmissions from the server. Those two packets should have been retransmitted but they weren't, the next log in the trace is a RST packet from the Client 24 seconds after packet 6. My question is related to what could be responsible for the failure to retransmit the server data from packets 3 & 5? I would assume that the retransmit would be at the operating system level but is there anyway the application could influence it and stop it being sent? A thread blocking or put to sleep or something like that?

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  • FragmentActivity cannot be resolve to a type

    - by Pratik
    I am starting learning for android tablet programming and I am able to updated my Eclipse as well as all new sdk for android. I have start testing application from this blog while at extending the FragmentActivity getting this error I have google it but not getting any solution. My project was created with 3.0 version having 11 level, all other packages are successfully used in the code but only this FragmentActivity was not able to resolve. Am I missing any library or any thing? My code public class Testing_newActivity extends FragmentActivity { // here the FragmentActivity getting error package not found for import /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //setContentView(R.layout.main); if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) { // If the screen is now in landscape mode, we can show the // dialog in-line so we don't need this activity. finish(); return; } if (savedInstanceState == null) { // During initial setup, plug in the details fragment. DetailsFragment details = new DetailsFragment(); details.setArguments(getIntent().getExtras()); getSupportFragmentManager().beginTransaction().add( android.R.id.content, details).commit(); } } } android manifest file <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.searce.testingnew" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="11" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" > <activity android:label="@string/app_name" android:name=".Testing_newActivity" > <intent-filter > <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

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  • OO model for nsxmlparser when delegate is not self

    - by richard
    Hi, I am struggling with the correct design for the delegates of nsxmlparser. In order to build my table of Foos, I need to make two types of webservice calls; one for the whole table and one for each row. It's essentially a master-query then detail-query, except the master-query-result-xml doesn't return enough information so i then need to query the detail for each row. I'm not dealing with enormous amounts of data. Anyway - previously I've just used NSXMLParser *parser = [[NSXMLParser alloc]init]; [parser setDelegate:self]; [parser parse]; and implemented all the appropriate delegate methods in whatever class i'm in. In attempt at cleanliness, I've now created two separate delegate classes and done something like: NSXMLParser *xp = [[NSXMLParser alloc]init]; MyMasterXMLParserDelegate *masterParserDelegate = [[MyMasterXMLParser]alloc]init]; [xp setDelegate:masterParserDelegate]; [xp parse]; In addition to being cleaner (in my opinion, at least), it also means each of the -parser:didStartElement implementations don't spend most of the time trying to figure out which xml they're parsing. So now the real crux of the problem. Before i split out the delegates, i had in the main class that was also implementing the delegate methods, a class-level NSMutableArray that I would just put my objects-created-from-xml in when -parser:didEndElement found the 'end' of each record. Now the delegates are in separate classes, I can't figure out how to have the -parser:didEndElement in the 'detail' delegate class "return" the created object to the calling class. At least, not in a clean OO way. I'm sure i could do it with all sorts of nasty class methods. Does the question make sense? Thanks.

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  • How to avoid hard-coded credentials in Sharepoint webpart?

    - by Bryan
    I am building a Sharepoint web part that will be used by all users, but can only be modified by admins. The web part connects to a web service which needs credentials. I hard coded credentials in the web part's code. query.Credentials = new System.Net.NetworkCredential("username", "password", "domain"); query is an instance of the web service class This may not be a good approach. In regard with security, the source code of the web apart is available to people who are not allowed to see the credentials. In normal ASP.net applications, credentials can be written into web.config and encrypted. A web part doesn't have a .config file associated. There is a application-level .config file for the whole sharepoint site, but I don't want to modify it for a single webpart. I wonder if there is a webpart-specific way to solve the credential problem? Say we provide a WebBrowsable property of that web part so that privileged users can modify credentials. If this is desirable, how should I make the property displayed in a password ("*") rather than in plain text? Thanks.

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  • ASP.NET MVC 2 user input to SQL 2008 Database problems

    - by Rob
    After my publish in VS2010 the entire website loads and pulls data from the database perfectly. I can even create new users through the site with the correct key code, given out to who needs access. I have two connection strings in my web.config file The first: <add xdt:Transform="SetAttributes" xdt:Locator="Match(name)" name="EveModelContainer" connectionString="metadata=res://*/Models.EdmModel.EveModel.csdl|res://*/Models.EdmModel.EveModel.ssdl|res://*/Models.EdmModel.EveModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=localhost;Initial Catalog=fleet;Persist Security Info=True;User ID=fleet;Password=****&quot;" providerName="System.Data.EntityClient" /> The second: <add xdt:Transform="SetAttributes" xdt:Locator="Match(name)" name="ApplicationServices" connectionString="Data Source=localhost;Initial Catalog=fleet;Persist Security Info=True;User ID=fleet;Password=****;MultipleActiveResultSets=True" /> The first one is the one that is needed to post data with the main application, EveModelContainer. Everything else is pulled using the standard ApplicationServices connection. Do you see anything wrong with my connectionstring? I'm at a complete loss here. The site works perfectly on my friends server and not on mine... Could it be a provider issue? And if I go to iis 7's manager console, and click .net users I get a pop up message saying the custom provider isn't a trusted provider do I want to allow it to run at a higher trust level. I'm at the point where I think its either my string or this trusted provider error... but I have no clue how to add to the trusted provider list... Thank you in advance!!!

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  • Preventing a heavy process from sinking in the swap file

    - by eran
    Our service tends to fall asleep during the nights on our client's server, and then have a hard time waking up. What seems to happen is that the process heap, which is sometimes several hundreds of MB, is moved to the swap file. This happens at night, when our service is not used, and others are scheduled to run (DB backups, AV scans etc). When this happens, after a few hours of inactivity the first call to the service takes up to a few minutes (consequent calls take seconds). I'm quite certain it's an issue of virtual memory management, and I really hate the idea of forcing the OS to keep our service in the physical memory. I know doing that will hurt other processes on the server, and decrease the overall server throughput. Having that said, our clients just want our app to be responsive. They don't care if nightly jobs take longer. I vaguely remember there's a way to force Windows to keep pages on the physical memory, but I really hate that idea. I'm leaning more towards some internal or external watchdog that will initiate higher-level functionalities (there is already some internal scheduler that does very little, and makes no difference). If there were a 3rd party tool that provided that kind of service is would have been just as good. I'd love to hear any comments, recommendations and common solutions to this kind of problem. The service is written in VC2005 and runs on Windows servers.

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  • Boost's "cstdint" Usage

    - by patt0h
    Boost's C99 stdint implementation is awfully handy. One thing bugs me, though. They dump all of their typedefs into the boost namespace. This leaves me with three choices when using this facility: Use "using namespace boost" Use "using boost::[u]<type><width>_t" Explicitly refer to the target type with the boost:: prefix; e.g., boost::uint32_t foo = 0; Option ? 1 kind of defeats the point of namespaces. Even if used within local scope (e.g., within a function), things like function arguments still have to be prefixed like option ? 3. Option ? 2 is better, but there are a bunch of these types, so it can get noisy. Option ? 3 adds an extreme level of noise; the boost:: prefix is often = to the length of the type in question. My question is: What would be the most elegant way to bring all of these types into the global namespace? Should I just write a wrapper around boost/cstdint.hpp that utilizes option ? 2 and be done with it? Also, wrapping the header like so didn't work on VC++ 10 (problems with standard library headers): namespace Foo { #include <boost/cstdint.hpp> using namespace boost; } using namespace Foo; Even if it did work, I guess it would cause ambiguity problems with the ::boost namespace.

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  • Keeping updated with the latest technologies.

    - by Prashanth
    I am a software developer and I have been programming since the past six years. I simply love the mental challenge involved in trying to come up with solutions to hard problems, reading up programming literature, blogs by prominent developers and so on. I work on Microsoft platform and I have trouble keeping up with the pace at which various frameworks are rolled out. Remoting,WCF,ASP.NET,ASP.NET MVC, LINQ, WPF, WWF, OSLO, ADO.NET data services, DSL tools etc etc. Even understanding all these frameworks at an abstract level and see how they are all tied up with MS vision itself is a major hurdle. Now when you add other non microsoft technologies, programming languages etc to the equation, I wonder how do people manage? Given that there are only 24 hours in a day, how does one keep himself updated about so many technology changes that happen everyday? My question is , is it even worth doing that? The thing is, I am also interested in other fields such as literature, science. I try my best to at least gain a superficial understanding of what is happening in other fields of my interest and don't want to give up on that :)

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  • SQL n:m Inheritance join

    - by Nightmares
    I want to join a table which contains n:m relationship between groups. (Groups are defined in a separate table). This table only has entries listing a member_group_id and a parent_group_id. Given this structure: id(int) | member_group_id(int) | parent_group_id(int) The "base" query looks like this: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.member_group_id = p1.member_group_id The "base" query correctly shows all relationships (I checked by doing it manually.) The problem is when I try to apply a where clause to this query to filter for a specific group as "point of origin" (the first group for which I want all parent groups) it returns only the closest parents. For example like this: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.member_group_id = p1.member_group_id where p1.group_id = 1 Can anyone give a clue how I can fix this? Or a different approach to realize this. (I suppose I could always do this in my C++ source code on the server side but I would have to transfer a entire table which has a high growth potential to the application server.) UPDATE: select p1.group_id, p2.group_id, p1.member_group_id, p2.member_group_id from group_member_group as p1 join group_member_group as p2 on p2.group_id = p1.member_group_id Typing mistake confirmed. Now I don't get past first level of inheritance period. Thanks at denied for pointing that out.

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  • Should I invest in GraniteDS for Flex + Java development?

    - by Boden
    I'm new to Flex development, and RIAs in general. I've got a CRUD-style Java + Spring + Hibernate service on top of which I'm writing a Flex UI. Currently I'm using BlazeDS. This is an internal application running on a local network. It's become apparent to me that the way RIAs work is more similar to a desktop application than a web application in that we load up the entire model and work with it directly on the client (or at least the portion that we're interested in). This doesn't really jive well with BlazeDS because really it only supports remoting and not data management, thus it can become a lot of extra work to make sure that clients are in sync and to avoid reloading the model which can be large (especially since lazy loading is not possible). So it feels like what I'm left with is a situation where I have to treat my Flex application more like a regular old web application where I do a lot of fine grained loading of data. LiveCycle is too expensive. The free version of WebOrb for Java really only does remoting. Enter GraniteDS. As far as I can determine, it's the only free solution out there that has many of the data management features of LiveCycle. I've started to go through its documentation a bit and suddenly feel like it's yet another quagmire of framework that I'll have to learn just to get an application running. So my question(s) to the StackOverflow audience is: 1) do you recommend GraniteDS, especially if my current Java stack is Spring + Hibernate? 2) at what point do you feel like it starts to pay off? That is, at what level of application complexity do you feel that using GraniteDS really starts to make development that much better? In what ways?

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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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  • getting data from dynamic schema

    - by coure2011
    I am using mongoose/nodejs to get data as json from mongodb. For using mongoose I need to define schema first like this var mongoose = require('mongoose'); var Schema = mongoose.Schema; var GPSDataSchema = new Schema({ createdAt: { type: Date, default: Date.now } ,speed: {type: String, trim: true} ,battery: { type: String, trim: true } }); var GPSData = mongoose.model('GPSData', GPSDataSchema); mongoose.connect('mongodb://localhost/gpsdatabase'); var db = mongoose.connection; db.on('open', function() { console.log('DB Started'); }); then in code I can get data from db like GPSData.find({"createdAt" : { $gte : dateStr, $lte: nextDate }}, function(err, data) { res.writeHead(200, { "Content-Type": "application/json", "Access-Control-Allow-Origin": "*" }); var body = JSON.stringify(data); res.end(body); }); How to define scheme for a complex data like this, you can see that subSection can go to any deeper level. [ { 'title': 'Some Title', 'subSection': [{ 'title': 'Inner1', 'subSection': [ {'titile': 'test', 'url': 'ab/cd'} ] }] }, .. ]

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  • How do I serialise a graph in Java without getting StackOverflowException?

    - by Tim Cooper
    I have a graph structure in java, ("graph" as in "edges and nodes") and I'm attempting to serialise it. However, I get "StackOverflowException", despite significantly increasing the JVM stack size. I did some googling, and apparently this is a well known limitation of java serialisation: that it doesn't work for deeply nested object graphs such as long linked lists - it uses a stack record for each link in the chain, and it doesn't do anything clever such as a breadth-first traversal, and therefore you very quickly get a stack overflow. The recommended solution is to customise the serialisation code by overriding readObject() and writeObject(), however this seems a little complex to me. (It may or may not be relevant, but I'm storing a bunch of fields on each edge in the graph so I have a class JuNode which contains a member ArrayList<JuEdge> links;, i.e. there are 2 classes involved, rather than plain object references from one node to another. It shouldn't matter for the purposes of the question). My question is threefold: (a) why don't the implementors of Java rectify this limitation or are they already working on it? (I can't believe I'm the first person to ever want to serialise a graph in java) (b) is there a better way? Is there some drop-in alternative to the default serialisation classes that does it in a cleverer way? (c) if my best option is to get my hands dirty with low-level code, does someone have an example of graph serialisation java source-code that can use to learn how to do it?

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  • How to exclude rows where matching join is in an SQL tree

    - by Greg K
    Sorry for the poor title, I couldn't think how to concisely describe this problem. I have a set of items that should have a 1-to-1 relationship with an attribute. I have a query to return those rows where the data is wrong and this relationship has been broken (1-to-many). I'm gathering these rows to fix them and restore this 1-to-1 relationship. This is a theoretical simplification of my actual problem but I'll post example table schema here as it was requested. item table: +------------+------------+-----------+ | item_id | name | attr_id | +------------+------------+-----------+ | 1 | BMW 320d | 20 | | 1 | BMW 320d | 21 | | 2 | BMW 335i | 23 | | 2 | BMW 335i | 34 | +------------+------------+-----------+ attribute table: +---------+-----------------+------------+ | attr_id | value | parent_id | +---------+-----------------+------------+ | 20 | SE | 21 | | 21 | M Sport | 0 | | 23 | AC | 24 | | 24 | Climate control | 0 | .... | 34 | Leather seats | 0 | +---------+-----------------+------------+ A simple query to return items with more than one attribute. SELECT item_id, COUNT(DISTINCT(attr_id)) AS attributes FROM item GROUP BY item_id HAVING attributes > 1 This gets me a result set like so: +-----------+------------+ | item_id | attributes | +-----------+------------+ | 1 | 2 | | 2 | 2 | | 3 | 2 | -- etc. -- However, there's an exception. The attribute table can hold a tree structure, via parent links in the table. For certain rows, parent_id can hold the ID of another attribute. There's only one level to this tree. Example: +---------+-----------------+------------+ | attr_id | value | parent_id | +---------+-----------------+------------+ | 20 | SE | 21 | | 21 | M Sport | 0 | .... I do not want to retrieve items in my original query where, for a pair of associated attributes, they related like attributes 20 & 21. I do want to retrieve items where: the attributes have no parent for two or more attributes they are not related (e.g. attributes 23 & 34) Example result desired, just the item ID: +------------+ | item_id | +------------+ | 2 | +------------+ How can I join against attributes from items and exclude these rows? Do I use a temporary table or can I achieve this from a single query? Thanks.

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  • Non standard interaction among two tables to avoid very large merge

    - by riko
    Suppose I have two tables A and B. Table A has a multi-level index (a, b) and one column (ts). b determines univocally ts. A = pd.DataFrame( [('a', 'x', 4), ('a', 'y', 6), ('a', 'z', 5), ('b', 'x', 4), ('b', 'z', 5), ('c', 'y', 6)], columns=['a', 'b', 'ts']).set_index(['a', 'b']) AA = A.reset_index() Table B is another one-column (ts) table with non-unique index (a). The ts's are sorted "inside" each group, i.e., B.ix[x] is sorted for each x. Moreover, there is always a value in B.ix[x] that is greater than or equal to the values in A. B = pd.DataFrame( dict(a=list('aaaaabbcccccc'), ts=[1, 2, 4, 5, 7, 7, 8, 1, 2, 4, 5, 8, 9])).set_index('a') The semantics in this is that B contains observations of occurrences of an event of type indicated by the index. I would like to find from B the timestamp of the first occurrence of each event type after the timestamp specified in A for each value of b. In other words, I would like to get a table with the same shape of A, that instead of ts contains the "minimum value occurring after ts" as specified by table B. So, my goal would be: C: ('a', 'x') 4 ('a', 'y') 7 ('a', 'z') 5 ('b', 'x') 7 ('b', 'z') 7 ('c', 'y') 8 I have some working code, but is terribly slow. C = AA.apply(lambda row: ( row[0], row[1], B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))), axis=1).set_index(['a', 'b']) Profiling shows the culprit is obviously B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))). However, standard solutions using merge/join would take too much RAM in the long run. Consider that now I have 1000 a's, assume constant the average number of b's per a (probably 100-200), and consider that the number of observations per a is probably in the order of 300. In production I will have 1000 more a's. 1,000,000 x 200 x 300 = 60,000,000,000 rows may be a bit too much to keep in RAM, especially considering that the data I need is perfectly described by a C like the one I discussed above. How would I improve the performance?

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  • Django sub-applications & module structure

    - by Rob Golding
    I am developing a Django application, which is a large system that requires multiple sub-applications to keep things neat. Therefore, I have a top level directory that is a Django app (as it has an empty models.py file), and multiple subdirectories, which are also applications in themselves. The reason I have laid my application out in this way is because the sub-applications are separated, but they would never be used on their own, outside the parent application. It therefore makes no sense to distribute them separately. When installing my application, the settings file has to include something like this: INSTALLED_APPS = ( ... 'myapp', 'myapp.subapp1', 'myapp.subapp2', ... ) ...which is obviously suboptimal. This also has the slightly nasty result of requiring that all the sub-applications are referred to by their "inner" name (i.e. subapp1, subapp2 etc.). For example, if I want to reset the database tables for subapp1, I have to type: python manage.py reset subapp1 This is annoying, especially because I have a sub-app called core - which is likely to conflict with another application's name when my application is installed in a user's project. Am I doing this completely wrongly, or is there away to force these "inner" apps to be referred to by their full name?

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  • How to maintain a persistant network-connection between two applications over a network?

    - by John
    I was recently approached by my management with an interesting problem - where I am pretty sure I am telling my bosses the correct information but I really want to make sure I am telling them the correct stuff. I am being asked to develop some software that has this function: An application at one location is constantly processing real-time data every second and only generates data if the underlying data has changed in any way. On the event that the data has changed send the results to another box over a network Maintains a persistent connection between the both machines, altering the remote box if for some reason the network connection went down From what I understand, I imagine that I need to do some reading on doing some sort of TCP/IP socket-level stuff. That way if the connection is dropped the remote location will be aware that the data it has received may be stale. However management seems to be very convinced that this can be accomplished using SOAP. I was under the impression that SOAP is more or less a way for a client to initiate a procedure from a server and get some results via the HTTP protocol. Am I wrong in assuming this? I haven't been able to find much information on how SOAP might be able to solve a problem like this. I feel like a lot of people around my office are using SOAP as a buzzword and that has generated a bit of confusion over what SOAP actually is - and is capable of. Any thoughts on how to accomplish this task would be appreciated!

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  • Javascript Getting Objects to Fallback to One Another

    - by Ian
    Here's a ugly bit of Javascript it would be nice to find a workaround. Javascript has no classes, and that is a good thing. But it implements fallback between objects in a rather ugly way. The foundational construct should be to have one object that, when a property fails to be found, it falls back to another object. So if we want a to fall back to b we would want to do something like: a = {sun:1}; b = {dock:2}; a.__fallback__ = b; then a.dock == 2; But, Javascript instead provides a new operator and prototypes. So we do the far less elegant: function A(sun) { this.sun = sun; }; A.prototype.dock = 2; a = new A(1); a.dock == 2; But aside from elegance, this is also strictly less powerful, because it means that anything created with A gets the same fallback object. What I would like to do is liberate Javascript from this artificial limitation and have the ability to give any individual object any other individual object as its fallback. That way I could keep the current behavior when it makes sense, but use object-level inheritance when that makes sense. My initial approach is to create a dummy constructor function: function setFallback(from_obj, to_obj) { from_obj.constructor = function () {}; from_obj.constructor.prototype = to_obj; } a = {sun:1}; b = {dock:2}; setFallback(a, b); But unfortunately: a.dock == undefined; Any ideas why this doesn't work, or any solutions for an implementation of setFallback? (I'm running on V8, via node.js, in case this is platform dependent)

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  • Memory leaks while using array of double

    - by Gacek
    I have a part of code that operates on large arrays of double (containing about 6000 elements at least) and executes several hundred times (usually 800) . When I use standard loop, like that: double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... } The memory usage rises for about 40MB (from 40MB at the beggining of the loop, to the 80MB at the end). When I force to use the garbage collector to execute at every iteration, the memory usage stays at the level of 40MB (the rise is unsignificant). double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... GC.Collect() } But the execution time is 3 times longer! (it is crucial) How can I force the C# to use the same area of memory instead of allocating new ones? Note: I have the access to the code of someObject class, so if it would be needed, I can change it.

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  • Dealing with SQLException with spring,hibernate & Postgres

    - by mad
    Hi im working on a project using HibernateDaoSUpport from my Daos from Spring & spring-ws & hibernate & postgres who will be used in a national application (means a lot of users) Actually, every exception from hibernate is automatically transformed into some specific Spring dataAccesException. I have a table with a keyword on the dabatase & a unique constraint on the keywords : no duplicate keywords is allowed. I have found twows ways to deal with with that in the Insert Dao: 1- Check for the duplicate manually (with a select) prior to doing your insert. I means that the spring transaction will have a SERIALIZABLE isolation level. The obvious drawback is that we have now 2 queries for a simple insert.Advantage: independent of the database 2-let the insert gone & catch the SqlException & convert it to a userfriendly message & errorcode to the final consumer of our webservices. Solution 2: Spring has developped a way to translate specific exeptions into customized exceptions. see http://www.oracle.com/technology/pub/articles/marx_spring.html In my case i would have a ConstraintViolationException. Ideally i would like to write a custom SQLExceptionTranslator to map the duplicate word constraint in the database with a DuplicateWordException. But i can have many unique constraints on the same table. So i have to get the message of the SQLEXceptions in order to find the name of the constraint declared in the create table "uq_duplicate-constraint" for example. Now i have a strong dependency with the database. Thanks in advance for your answers & excuse me for my poor english (it is not my mother tongue)

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  • Formatting associative array declaration

    - by Drew Stephens
    When declaring an associative array, how do you handle the indentation of the elements of the array? I've seen a number of different styles (PHP syntax, since that's what I've been in lately). This is a pretty picky and trivial thing, so move along if you're interested in more serious pursuits. 1) Indent elements one more level: $array = array( 'Foo' => 'Bar', 'Baz' => 'Qux' ); 2) Indent elements two levels: $array = array( 'Foo' => 'Bar', 'Baz' => 'Qux' ); 3) Indent elements beyond the array constructor, with closing brace aligned with the start of the constructor: $array = array( 'Foo' => 'Bar', 'Baz' => 'Qux' ); 4) Indent elements beyond the array construct, with closing brace aligned with opening brace: $array = array( 'Foo' => 'Bar', 'Baz' => 'Qux' ); Personally, I like #3—the broad indentation makes it clear that we're at a break point in the code (constructing the array), and having the closing brace floating a bit to the left of all of the array's data makes it clear that this declaration is done.

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