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  • What are logical and path queries

    - by NomeN
    I'm reading a paper which mentions that a language for refactoring has three specific requirements. functional features (like ML) logical queries (like Datalog) path queries (like Datalog) I know what they mean by functional features, but I'm not totally clear on the latter two and can't find a clear explanation either. Although I have a good idea after what I could find on the subjects, I need to be sure so here goes: Could the SO-community please clearly explain to me what logical queries and path queries are? Or at the very least what the people from the paper meant?

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  • appending to cursor in oracle

    - by Omnipresent
    I asked a question yesterday which got answers but didnt answer the main point. I wanted to reduce amount of time it took to do a MINUS operation. Now, I'm thinking about doing MINUS operation in blocks of 5000, appending each iterations results to the cursor and finally returning the cursor. I have following: V_CNT NUMBER :=0; V_INTERVAL NUMBER := 5000; begin select count(1) into v_cnt from TABLE_1 while (v_cnt > 0) loop open cv_1 for SELECT A.HEAD,A.EFFECTIVE_DATE, FROM TABLE_1 A WHERE A.TYPE_OF_ACTION='6' AND A.EFFECTIVE_DATE >= ADD_MONTHS(SYSDATE,-15) AND A.ROWNUM <= V_INTERVAL MINUS SELECT B.head,B.EFFECTIVE_DATE, FROM TABLE_2 B AND B.ROWNUM <= V_INTERVAL V_CNT := V_CNT - V_INTERVAL; END LOOP; end; However, as you see...in each iteration the cursor is overwritten. How can I change the code so that in each iteration it appends to cv_1 cursor rather than overwriting?

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  • Advice on how to complete specific MySQL JOIN

    - by Tim
    Hello, I have a mysql table jobs. This is the basic structure of jobs. id booked_user_id assigned_user_id I then also have another table, meta. Meta has the structure: id user_id first_name last_name How can I join these tables so that both booked_user_id and assigned_user_id can access meta.first_name? Thanks for your advice Tim

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  • Faster integer division when denominator is known?

    - by aaa
    hi I am working on GPU device which has very high division integer latency, several hundred cycles. I am looking to optimize divisions. All divisions by denominator which is in a set { 1,3,6,10 }, however numerator is a runtime positive value, roughly 32000 or less. due to memory constraints, lookup table is not option. Can you think of alternatives? I have thought of computing float point inverses, and using those to multiply numerator. Thanks

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  • How to recognize what indexes are not used?

    - by tomaszs
    I have a table in MySQL with 7 indexes, most of them are on more than one column. I think here is too much indexes. Is there any way to get statistics of what indexes are used more by all thousands of queries to this database and what are less worthy so I know what index to consider to remove in first place?

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  • SQL - How can I apply a "semi-unique" constraint?

    - by Erin Drummond
    Hi, I have a (simplified) table consisting of three columns: id INT PRIMARY KEY NOT NULL AUTO_INCREMENT, foreignID INT NOT NULL, name VARCHAR NOT NULL Basically, I would like to add a constraint (at the database level rather than at the application level) where it only possible for one unique 'name' to exist per foreignID. For example, given the data (id, foreignid, name): 1,1,Name1 2,1,Name2 3,1,Name3 4,2,Name1 5,2,Name2 I want the constraint to fail if the user tries to insert another 'Name3' under foreignId 1, but succeed if the user tries to insert 'Name3' under foreignId 2. For this reason I cannot simply make the whole column UNIQUE. I am having difficulty coming up with a SQL expression to achieve this, can anybody help me? Thanks

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  • UPDATE query that fixes orphaned records

    - by Jed
    I have an Access database that has two tables that are related by PK/FK. Unfortunately, the database tables have allowed for duplicate/redundant records and has made the database a bit screwy. I am trying to figure out a SQL statement that will fix the problem. To better explain the problem and goal, I have created example tables to use as reference: You'll notice there are two tables, a Student table and a TestScore table where StudentID is the PK/FK. The Student table contains duplicate records for students John, Sally, Tommy, and Suzy. In other words the John's with StudentID's 1 and 5 are the same person, Sally 2 and 6 are the same person, and so on. The TestScore table relates test scores with a student. Ignoring how/why the Student table allowed duplicates, etc - The goal I'm trying to accomplish is to update the TestScore table so that it replaces the StudentID's that have been disabled with the corresponding enabled StudentID. So, all StudentID's = 1 (John) will be updated to 5; all StudentID's = 2 (Sally) will be updated to 6, and so on. Here's the resultant TestScore table that I'm shooting for (Notice there is no longer any reference to the disabled StudentID's 1-4): Can you think of a query (compatible with MS Access's JET Engine) that can accomplish this goal? Or, maybe, you can offer some tips/perspectives that will point me in the right direction. Thanks.

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  • Combine static files or load in parallel

    - by Niall Collins
    I am at present introducing code to my site to combine css and javascript files. Is there a way without having to include an external library to load javascript asynchronously or in parallel? I have read on some blogs that combining of files can be counter productive as the load of the http request can be large and its better to load multiple files in parallel. Opinions on this? I am caching my javascript/css. And would have thought it was better to combine rather than have multiple http requests.

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  • Where is my python script spending time? Is there "missing time" in my cprofile / pstats trace?

    - by fmark
    I am attempting to profile a long running python script. The script does some spatial analysis on raster GIS data set using the gdal module. The script currently uses three files, the main script which loops over the raster pixels called find_pixel_pairs.py, a simple cache in lrucache.py and some misc classes in utils.py. I have profiled the code on a moderate sized dataset. pstats returns: p.sort_stats('cumulative').print_stats(20) Thu May 6 19:16:50 2010 phes.profile 355483738 function calls in 11644.421 CPU seconds Ordered by: cumulative time List reduced from 86 to 20 due to restriction <20> ncalls tottime percall cumtime percall filename:lineno(function) 1 0.008 0.008 11644.421 11644.421 <string>:1(<module>) 1 11064.926 11064.926 11644.413 11644.413 find_pixel_pairs.py:49(phes) 340135349 544.143 0.000 572.481 0.000 utils.py:173(extent_iterator) 8831020 18.492 0.000 18.492 0.000 {range} 231922 3.414 0.000 8.128 0.000 utils.py:152(get_block_in_bands) 142739 1.303 0.000 4.173 0.000 utils.py:97(search_extent_rect) 745181 1.936 0.000 2.500 0.000 find_pixel_pairs.py:40(is_no_data) 285478 1.801 0.000 2.271 0.000 utils.py:98(intify) 231922 1.198 0.000 2.013 0.000 utils.py:116(block_to_pixel_extent) 695766 1.990 0.000 1.990 0.000 lrucache.py:42(get) 1213166 1.265 0.000 1.265 0.000 {min} 1031737 1.034 0.000 1.034 0.000 {isinstance} 142740 0.563 0.000 0.909 0.000 utils.py:122(find_block_extent) 463844 0.611 0.000 0.611 0.000 utils.py:112(block_to_pixel_coord) 745274 0.565 0.000 0.565 0.000 {method 'append' of 'list' objects} 285478 0.346 0.000 0.346 0.000 {max} 285480 0.346 0.000 0.346 0.000 utils.py:109(pixel_coord_to_block_coord) 324 0.002 0.000 0.188 0.001 utils.py:27(__init__) 324 0.016 0.000 0.186 0.001 gdal.py:848(ReadAsArray) 1 0.000 0.000 0.160 0.160 utils.py:50(__init__) The top two calls contain the main loop - the entire analyis. The remaining calls sum to less than 625 of the 11644 seconds. Where are the remaining 11,000 seconds spent? Is it all within the main loop of find_pixel_pairs.py? If so, can I find out which lines of code are taking most of the time?

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  • What kind of data processing problems would CUDA help with?

    - by Chris McCauley
    Hi, I've worked on many data matching problems and very often they boil down to quickly and in parallel running many implementations of CPU intensive algorithms such as Hamming / Edit distance. Is this the kind of thing that CUDA would be useful for? What kinds of data processing problems have you solved with it? Is there really an uplift over the standard quad-core intel desktop? Chris

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  • SQL Server Group Concat with Different characters

    - by Molloch
    I have looked through a number of solutions to emulating "Group concat" functionality in SQL Server. I wanted to make a more human readable solution though and I can't work out how to do it. I have a view: ParentID | ChildName Which contains the records, for example: 1 | Max 1 | Jessie 2 | Steven 2 | Lucy 2 | Jake 3 | Mark I want to "Group Concat" these to get: 1 | Max and Jessie 2 | Steven, Lucy and Jake 3 | Mark So If there is only 1 child, just return name, if there are more than one, concat the last 2 with an ' and ' and all others with a ', '. I am a bit stuck on how to do this without resorting to CLR, which I don't want to do. I am happy with a function - but speed is an issue and how do I determine the child number so I can choose between ' and ', ', ' or ''?

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  • How to speed up the reading of innerHTML in IE8?

    - by Dennis Cheung
    I am using JQuery with the DataTable plugin, and now I have a big performnce issue on the following line. aLocalData[jInner] = nTds[j].innerHTML; // jquery.dataTables.js:2220 I have a ajax call, and result string in HTML format. I convert them into HTML nodes, and that part is ok. var $result = $('<div/>').html(result).find("*:first"); // simlar to $result=$(result) but much more faster in Fx Then I activate enable the result from a plain table to a sortable datatable. The speed is acceptable in Fx (around 4sec for 900 rows), but unacceptable in IE8 (more then 100 seconds). I check it deep using the buildin profiler, and found the above single line take all 99.9% of the time, how can I speed it up? anything I missed? nTrs = oSettings.nTable.getElementsByTagName('tbody')[0].childNodes; for ( i=0, iLen=nTrs.length ; i<iLen ; i++ ) { if ( nTrs[i].nodeName == "TR" ) { iThisIndex = oSettings.aoData.length; oSettings.aoData.push( { "nTr": nTrs[i], "_iId": oSettings.iNextId++, "_aData": [], "_anHidden": [], "_sRowStripe": '' } ); oSettings.aiDisplayMaster.push( iThisIndex ); aLocalData = oSettings.aoData[iThisIndex]._aData; nTds = nTrs[i].childNodes; jInner = 0; for ( j=0, jLen=nTds.length ; j<jLen ; j++ ) { if ( nTds[j].nodeName == "TD" ) { aLocalData[jInner] = nTds[j].innerHTML; // jquery.dataTables.js:2220 jInner++; } } } }

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  • nested linq-to-sql queries

    - by ile
    var result = ( from contact in db.Contacts join user in db.Users on contact.CreatedByUserID equals user.UserID orderby contact.ContactID descending select new ContactListView { ContactID = contact.ContactID, FirstName = contact.FirstName, LastName = contact.LastName, Company = (from field in contact.XmlFields.Descendants("Company") select field.Value).SingleOrDefault().ToString() }).Take(10); Here I described how my database tables look like. So, contacts table has one field that is xml type. In that field is stored Company filename and I need to read it. I tried it using this way: Company = (from field in contact.XmlFields.Descendants("Company") select field.Value).SingleOrDefault().ToString() }).Take(10); but I get following error: Member access 'System.String Value' of 'System.Xml.Linq.XElement' not legal on type 'System.Collections.Generic.IEnumerable`1[System.Xml.Linq.XElement]. Any solution for this? Thanks in advance, Ile

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  • Showing response time in a rails app.

    - by anshul
    I want to display a This page took x seconds widget at the bottom of every page in my rails application. I would like x to reflect the approximate amount of time the request spent on my server. What is the usual way this is done in Rails?

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  • SQL Overlapping and Multi-Column Indexes

    - by durilai
    I am attempting to tune some stored procedures and have a question on indexes. I have used the tuning advisor and they recommended two indexes, both for the same table. The issue is one index is for one column and the other is for multiple columns, of which it includes the same column from the first. My question is why and what is the difference? CREATE NONCLUSTERED INDEX [_dta_index_Table1_5_2079723603__K23_K17_K13_K12_K2_K10_K22_K14_K19_K20_K9_K11_5_6_7_15_18] ON [dbo].[Table1] ( [EfctvEndDate] ASC, [StuLangCodeKey] ASC, [StuBirCntryCodeKey] ASC, [StuBirStOrProvncCodeKey] ASC, [StuKey] ASC, [GndrCodeKey] ASC, [EfctvStartDate] ASC, [StuHspncEnctyIndctr] ASC, [StuEnctyMsngIndctr] ASC, [StuRaceMsngIndctr] ASC, [StuBirDate] ASC, [StuBirCityName] ASC ) INCLUDE ( [StuFstNameLgl], [StuLastOrSrnmLgl], [StuMdlNameLgl], [StuIneligSnorImgrntIndctr], [StuExpctdGrdtngClYear] ) WITH (SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF) ON [PRIMARY] go CREATE NONCLUSTERED INDEX [_dta_index_Table1_5_2079723603__K23] ON [dbo].[Table1] ( [EfctvEndDate] ASC )WITH (SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF) ON [PRIMARY]

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  • Struts DB query execution problem

    - by henderunal
    Hello, I am trying to insert a data to my db2 9.7 database from IBM RAD 7.5 using struts 1.3 But when i execute the query i got this errors: http://pastebin.com/3UPTVKbh KayitBean kayit=(KayitBean)form; //String name = kayit.getName(); String name="endee"; DBConn hb = new DBConn(); Connection conn =hb.getConnection(); System.out.println("basarili"); //String sql = "SELECT * FROM ENDER.\"MEKANDENEME\""; String sql = "INSERT INTO ENDER.\"MEKANDENEME\" VALUES (\'endere\' ,\'bos\');"; System.out.println(sql); System.out.println("basarili2"); PreparedStatement ps = conn.prepareStatement(sql); System.out.println("basarili3"); ResultSet rs = ps.executeQuery(); // String ender=rs.getArray(1).toString(); System.out.println("basarili4"); // System.out.println(rs); conn.close(); I am receiving this after System.out.println("basarili3");" Please help me.

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  • mysql order-by original "where order"

    - by Benjamin Dobnikar
    I have this order-by problem I canot crack. I select from my table like this: SELECT * FROM 'sidemodules' WHERE name = 'module1' OR name = 'module2' OR 'name3' Which returns me the modules I want. But the modules lie the table, say in this order: module3 module1 module2 And they are returned to me in this order. How can I get them to display in order AS IN THE WHERE CLAUSE (1,2,3) ? Big thanks!

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  • Need help in tuning a sql-query

    - by Viper
    Hello, i need some help to boost this SQL-Statement. The execution time is around 125ms. During the runtime of my program this sql (better: equally structured sqls for different tables) will be called 300.000 times. The average row count in the tables lies around 10.000.000 rows and new rows (updates/inserts) will be added with a timestamp each day. Data which are interesting for this particular export-program lies in the last 1-3 days. Maybe this is helpful for an index to create. The data i need is the current valid row for a given id and the forerunner datarow to get the updates (if exists). We use a Oracle 11g database and Dot.Net Framework 3.5 SQL-Statement to boost: select ID_SOMETHING, -- Number(12) ID_CONTRIBUTOR, -- Char(4 Byte) DATE_VALID_FROM, -- DATE DATE_VALID_TO -- DATE from TBL_SOMETHING XID where ID_SOMETHING = :ID_INSTRUMENT and ID_CONTRIBUTOR = :ID_CONTRIBUTOR and DATE_VALID_FROM <= :EXPORT_DATE and DATE_VALID_TO >= :EXPORT_DATE order by DATE_VALID_FROM asc; Here i uploaded the current Explain-Plan for this query. I'm not a database expert so i don't know which index-type would fit best for this requirement. I have seen that there are many different possible index-types which could be applied. Maybe Oracle Optimizer Hints are helpful, too. Does anyone has a good idea for tuning this sql or can point me in a right direction?

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  • Web Page execution

    - by Sweta Jha
    I have a web page which brings 13K+ records in 20 seconds. There is a menu on the page, clicking on which navigates me to another page which is very lightweight. Displaying the data (13K+) took only 20 seconds whereas navigating from that page took much longer, more than 2 mins. Can you tell me why is the latter taking so much of time. I've stopped the page_load code execution on click of the menu. I've disabled the viewstate for that page as well.

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  • MySQL: Request to select the last 10 send/received messages to/by different users

    - by Yako malin
    I want to select the 10 last messages you received OR you sent TO different users. For example the results must be shown like that: 1. John1 - last message received 04/17/10 3:12 2. Thomy - last message sent 04/16/10 1:26 3. Pamela - last message received 04/12/10 3:51 4. Freddy - last message received 03/28/10 9:00 5. Jack - last message sent 03/20/10 4:53 6. Tom - last message received 02/01/10 7:41 ..... Table looks like: CREATE TABLE `messages` ( `id` int(11) NOT NULL AUTO_INCREMENT, `time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, `sender` int(11) DEFAULT NULL, `receiver` int(11) DEFAULT NULL, `content` text ) I think Facebook (and the iPhone) use this solution. When you go to your mail box, you have the last messages received/sent grouped by Users (friends). So I will take an example. If I have theses messages (THEY ARE ORDERED YET): **Mike** **Tom** **Pam** Mike Mike **John** John Pam **Steve** **Bobby** Steve Steve Bobby Only Message with ** should be returned because they are the LAST messages I sent/received By User. In fact I want the last message of EACH discussion. What is the solution?

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  • Input string was not in the correct format using int.Parse

    - by JDWebs
    I have recently been making a login 'representation' which is not secure. So before answering, please note I am aware of security risks etc., and this will not be on a live site. Also note I am a beginner :P. For my login representation, I am using LINQ to compare values of a DDL to select a username and a Textbox to enter a password, when a login button is clicked. However, an error is thrown 'Input string was not in the correct format', when using int.Parse. Front End: <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login_Test.aspx.cs" Inherits="Login_Login_Test" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Login Test</title> </head> <body> <form id="LoginTest" runat="server"> <div> <asp:DropDownList ID="DDL_Username" runat="server" Height="20px" DataTextField="txt"> </asp:DropDownList> <br /> <asp:TextBox ID="TB_Password" runat="server" TextMode="Password"></asp:TextBox> <br /> <asp:Button ID="B_Login" runat="server" onclick="B_Login_Click" Text="Login" /> <br /> <asp:Literal ID="LI_Result" runat="server"></asp:Literal> </div> </form> </body> </html> Back End: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class Login_Login_Test : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { Binder(); } } private void Binder() { using (DataClassesDataContext db = new DataClassesDataContext()) { DDL_Username.DataSource = from x in db.DT_Honeys select new { id = x.UsernameID, txt = x.Username }; DDL_Username.DataValueField = "id"; DDL_Username.DataTextField = "txt"; DDL_Username.DataBind(); } } protected void B_Login_Click(object sender, EventArgs e) { if (TB_Password.Text != "") { using (DataClassesDataContext db = new DataClassesDataContext()) { DT_Honey blah = new DT_Honey(); blah = db.DT_Honeys.SingleOrDefault(x => x.UsernameID == int.Parse(DDL_Username.SelectedValue.ToString())); if (blah == null) { LI_Result.Text = "Something went wrong :/"; } if (blah.Password == TB_Password.Text) { LI_Result.Text = "Credentials recognised :-)"; } else { LI_Result.Text = "Error with credentials :-("; } } } } } I am aware this problem is very common, but none of the help I have found online is useful/relevant. Any help/suggestions appreciated; thank you for your time :-).

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