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  • Is it possible to select data with max value for a column using Criteria in Hibernate?

    - by Palo
    Lets say I have the following mapping: <hibernate-mapping package="mypackage"> <class name="User" table="user"> <id name="id" column="id"> <generator class="native"></generator> </id> <property name="name" /> <property name="age" /> </class> </hibernate-mapping> Is it possible to select the oldest user (that is age is maximal) using Criteria in Hibernate? I can imagine that i could do this with 2 selects. (first select total number of users and then order the entries descending by age and select the first entry). But is it possible with a single select? Thank you Palo

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  • jQuery async ajax query and returning value problem (scope, closure)

    - by glebovgin
    Hi. Code not working because of async query and variable scope problem. I can't understand how to solve this. Change to $.ajax method with async:false - not an option. I know about closures, but how I can implement it here - don't know. I've seen all topics here about closures in js and jQuery async problems - but still nothing. Help, please. Here is the code: var map = null; var marker; var cluster = null; function refreshMap() { var markers = []; var markerImage = new google.maps.MarkerImage('/images/image-1_32_t.png', new google.maps.Size(32, 32)); $.get('/get_users.php',{},function(data){ if(data.status == 'error') return false; var users = data.users; // here users.length = 1 - this is ok; for(var i in users) { //here I have every values from users - ok var latLng = new google.maps.LatLng(users[i].lat, users[i].lng); var mark = new google.maps.Marker({ position: latLng, icon: markerImage }); markers.push(mark); alert(markers.length); // length 1 } },'json'); alert(markers.length); // length 0 //if I have alert() above - I get result cluster = new MarkerClusterer(map, markers, { maxZoom: null, gridSize: null }); } Thanks.

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  • Will an IO blocked process show 100% CPU utilization in 'top' output?

    - by Alex Stoddard
    I have an analysis that can be parallelized over a different number of processes. It is expected that things will be both IO and CPU intensive (very high throughput short-read DNA alignment if anyone is curious.) The system running this is a 48 core linux server. The question is how to determine the optimum number of processes such that total throughput is maximized. At some point the processes will presumably become IO bound such that adding more processes will be of no benefit and possibly detrimental. Can I tell from standard system monitoring tools when that point has been reached? Would the output of top (or maybe a different tool) enable me to distinguish between a IO bound and CPU bound process? I am suspicious that a process blocked on IO might still show 100% CPU utilization.

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  • Best practice for avoiding locks on a heavily read table?

    - by Luiggi
    Hi, I have a big database (~4GB), with 2 large tables (~3M records) having ~180K SELECTs/hour, ~2k UPDATEs/hour and ~1k INSERTs+DELETEs/hour. What would be the best practice to guarantee no locks for the reading tasks while inserting/updating/deleting? I was thinking about using a NOLOCK hint, but there is so much discussed about this (is good, is bad, it depends) that I'm a bit lost. I must say I've tried this in a dev environment and I didn't find any problems, but I don't want to put it on production until I get some feedback... Thank you! Luiggi

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  • Merging some columns of two mysql tables where id = fileid

    - by garg
    There are two tables TableA filedata_id | user_id | filename 1 | 1 | file.txt 2 | 1 | file2.txt TableB a_id | date | filedataid | counter | state | cat_id | subcat_id | med_id 99 | 1242144 | 1 | 2 | v | 55 | 56 | 90 100 | 1231232 | 2 | 3 | i | 44 | 55 | 110 I want to move columns cat_id, subcat_id, med_id to TableA where tableA.filedata_id = TableB.filedataid The result should be: TableA filedata_id | user_id | filename | cat_id | subcat_id | med_id 1 | 1 | file.txt | 55 | 56 | 90 2 | 1 | file2.txt | 44 | 55 | 110 and so on. Is there a way to do this easily?

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  • LinqtoSql Pre-compile Query problem with Count() on a group by

    - by Joe Pitz
    Have a LinqtoSql query that I now want to precompile. var unorderedc = from insp in sq.Inspections where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime && insp.Model == "EP" && insp.TestResults != "P" group insp by new { insp.TestResults, insp.FailStep } into grp select new { FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0), CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0), grp.Key.TestResults, grp.Key.FailStep, PercentFailed = Convert.ToDecimal(1.0 * grp.Count() / tcount * 100) }; I have created this delegate: public static readonly Funct<SQLDataDataContext, int, string, string, DateTime, DateTime, IQueryable<CalcFailedTestResult>> GetInspData = CompiledQuery.Compile((SQLDataDataContext sq, int tcount, string strModel, string strTest, DateTime dStartTime, DateTime dEndTime, IQueryable<CalcFailedTestResult> CalcFailed) => from insp in sq.Inspections where insp.TestTimeStamp > dStartTime && insp.TestTimeStamp < dEndTime && insp.Model == strModel && insp.TestResults != strTest group insp by new { insp.TestResults, insp.FailStep } into grp select new { FailedCount = (grp.Key.TestResults == "F" ? grp.Count() : 0), CancelCount = (grp.Key.TestResults == "C" ? grp.Count() : 0), grp.Key.TestResults, grp.Key.FailStep, PercentFailed = Convert.ToDecimal(1.0 * grp.Count() / tcount * 100) }); The syntax error is on the CompileQuery.Compile() statement It appears to be related to the use of the select new {} syntax. In other pre-compiled queries I have written I have had to just use the select projection by it self. In this case I need to perform the grp.count() and the immediate if logic. I have searched SO and other references but cannot find the answer.

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  • Optimizing landing pages

    - by Oleg Shaldybin
    In my current project (Rails 2.3) we have a collection of 1.2 million keywords, and each of them is associated with a landing page, which is effectively a search results page for a given keywords. Each of those pages is pretty complicated, so it can take a long time to generate (up to 2 seconds with a moderate load, even longer during traffic spikes, with current hardware). The problem is that 99.9% of visits to those pages are new visits (via search engines), so it doesn't help a lot to cache it on the first visit: it will still be slow for that visit, and the next visit could be in several weeks. I'd really like to make those pages faster, but I don't have too many ideas on how to do it. A couple of things that come to mind: build a cache for all keywords beforehand (with a very long TTL, a month or so). However, building and maintaing this cache can be a real pain, and the search results on the page might be outdated, or even no longer accessible; given the volatile nature of this data, don't try to cache anything at all, and just try to scale out to keep up with traffic. I'd really appreciate any feedback on this problem.

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  • Using FILE_FLAG_NO_BUFFERING will return noticeable speed gain?

    - by 9dan
    Recently noticed detail description of FILE_FLAG_NO_BUFFERING flag in MSDN, and read several Google search results about unbuffered I/O in Windows. http://msdn.microsoft.com/en-us/library/aa363858(v=vs.85).aspx I wondering now, is it really important to consider unbuffered option in file I/O programming? Because many programs use plain old C stream I/O or C++ iostream, I didn't gave any attention to FILE_FLAG_NO_BUFFERING flag before. Let's say we are developing photo explorer program like Picasa. If we implement unbuffered I/O, could thumbnail display speed show noticeable difference in ordinary users?

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  • Similar SQL queries returning different results...

    - by Pablo
    Here are the SQL Queries: $sql1 = "SELECT count(thread) AS total FROM comments WHERE thread=1 AND parent_id=0 "; $sql2 = "SELECT count(thread) AS total FROM comments, users WHERE thread=1 AND parent_id=0 AND users.user_id=comments.user_id "; $sql3 = "SELECT comments.*, users.username AS username FROM comments, users WHERE thread=1 AND parent_id=0 AND users.user_id=comments.user_id ORDER BY date LIMIT 10, 5 "; My question is why would $sql1 and $sql2 would return two different results? $sql1 returns 61 rows $sql2 returns 56 rows The 5th line in $sql2 is just for testing, is not required, is just a variation of $sql1 which gets the total rows for a pagination.

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  • Wpf. Chart optimization. More than million points

    - by Evgeny
    I have custom control - chart with size, for example, 300x300 pixels and more than one million points (maybe less) in it. And its clear that now he works very slowly. I am searching for algoritm which will show only few points with minimal visual difference. I have link to component which have functionallity exactly what i need (2 million points demo): http://www.mindscape.co.nz/demo/SilverlightElements/demopage.html#/ChartOverviewPage I will be grateful for any matherials, links or thoughts how to realize such functionallity.

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  • PHP login, getting wrong count value from query / fetch array

    - by Chris
    Hello, *EDIT*Thanks to the comments below it has been figured out that the problem lies with the md5, without everything works as it should. But how do i implent the md5 then? I am having some troubles with the following code below to login. The database and register system are already working. The problem lies that it does not find any result at all in the query. IF the count is 0 it should redirect the user to a secured page. But this only works if i write count = 0, but this should be 0 , only if the user name and password is found he should be directed to the secure (startpage) of the site after login. For example root (username) root (password) already exists but i cannot seem to properly login with it. <?php session_start(); if (!empty($_POST["send"])) { $username = ($_POST["username"]); $password = (md5($_POST["password"])); $count = 0; $con = mysql_connect("localhost" , "root", ""); mysql_select_db("testdb", $con); $result = mysql_query("SELECT name, password FROM user WHERE name = '".$username."' AND password = '".$password."' ") or die("Error select statement"); $count = mysql_num_rows($result); if($count > 0) // always goes the to else, only works with >=0 but then the data is not found in the database, hence incorrect { $row = mysql_fetch_array($result); $_SESSION["username"] = $row["name"]; header("Location: StartPage.php"); } else { echo "Wrong login data, please try again"; } mysql_close($con); } ?>

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  • Where should I place a function that I want to run before the cached page is served (Drupal)

    - by kidbrax
    We have a intranet site that runs on Drupal. If an employee hits the site from outside our network they are required to login first. If they are already in our network, they can browse around freely. So we have a function that checks where they are coming from and redirects them to a login page if they are from outside. If we enable caching, they are not redirected because the cached page is rendered without running our function. The code currently exists inside of the theme_preprocess function. Where can I put it so that it always runs before the cached pages are served?

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  • Basic SQL Query, I am newbie

    - by user3530547
    I just started my database and query class on Monday. We met on Monday and just went over the syllabus, and on Wednesday the network at school was down so we couldn't even do the power point lecture. Right now I am working on my first homework assignment and I am almost finished but I am having trouble on one question. Here is is... Write a SELECT statement that returns one column from the Customers table named FullName that joins the LastName and FirstName columns. Format the columns with the last name, a comma, a space, and the first name like this: Doe, John Sort the result set by last name in ascending sequence. Return only the contacts whose last name begins with letters from M to Z. Here is what I have so far... USE md0577283 SELECT FirstName,LastName FROM Customers ORDER BY LastName,FirstName My question is how do I format is Lastname, FirstName like the professor wants and how do I only select names M-Z? If someone could point me in the right direction I would greatly appreciate it. Thank you. PS With all do respect, I didn't ask for the answer I asked for a nudge in the right direction so why the down vote guys?

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  • Maven + Tomcat acceleration

    - by Bar
    I am writing a web application with Maven in the Eclipse IDE, and use Tomcat servlet container. So, I run Maven like this: mvn clean compile. It is reasonable that after this oepration I must re-run Tomcat so it can reinitialize the context (Sysdeo Tomcat launcher helps a lot). The problem is Maven execution and subsequebt Tomcat re-running takes noticable amount of time (like 10+ seconds for Maven and 20+ sec. for Tomcat, because of logging, Hibernate mappings, etc.) every time I do it. Is there any automated and more faster solution for these two operatioins? As I see it, a way better solution can be moving re-compiled classes only to the target dir.

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  • Joining tables, if percentage is above certain value

    - by CluelessGerman
    My question is similar to this one: Compare rows and get percentage However, little different. I adapted my question to the other post. I got 2 tables. First table: user_id | post_id 1 1 1 2 1 3 2 12 2 15 And second table: post_id | rating 1 1 1 2 1 3 2 1 2 5 3 null 3 1 3 4 12 4 15 1 So now I would like to count the rating for each post, in the second table. If the rating has more than, lets say, 50% positive ratings than I want to get the post_id and going it to the post_id from table one and add 1 to the user_id. At the end it would return the user_id with the number of positive posts. The result for above table would be: user_id | helpfulPosts 1 2 2 1 The post with post_id 1 and 3 have positive rating, because more than 50% have ratings of 1-3. The post with id = 2 is not positive, because the rating is exactly 50%. How would I achieve this? For clarification: It's a mysql rdbm and a positive post, is one where the number of rating_ids with 1, 2 and 3 are more than half of the overall rating. Basically the same thing, from the other thread I posted above.

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  • Query decendants in XML to Linq

    - by Gordon
    I have the following xml data: <portfolio> <item> <title>Site</title> <description>Site.com is a </description> <url>http://www.site.com</url> <photos> <photo url="http://www.site.com/site/thumbnail.png" thumbnail="true" description="Main" /> <photo url="http://www.site.com/site/1.png" thumbnail="false" description="Main" /> </photos> </item> </portfolio> In c# I am using the following link query: List list = new List(); XDocument xmlDoc = XDocument.Load(HttpContext.Current.Server.MapPath("~/app_data/portfolio.xml")); list = (from portfolio in xmlDoc.Descendants("item") select new PortfolioItem() { Title = portfolio.Element("title").Value, Description = portfolio.Element("description").Value, Url = portfolio.Element("url").Value }).ToList(); How do I go about querying the photos node? In the PortfolioItem class I have a property: List Photos {get;set;} Any ideas would be greatly appreciated!

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  • MySQL select/where statement

    - by expo101
    I have a webapplication linked to a mysql database with the following fields: field 1:trip_id field 2:trip_destination field 3:trip_description field 4:trip_duration In the webapplication I have a listbox based on the following: ListBox value =1: trip duration 1 - 5 days ListBox value =2: trip duration 6 - 10 days Listbox value =3: trip duration 11 -20 days ListBox value =4: trip duration over 20 days How do I put this in the sql select statement?

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  • MySQL - Limit a left join to the first date-time that occurs?

    - by John M
    Simplified table structure (the tables can't be merged at this time): TableA: dts_received (datetime) dts_completed (datetime) task_a (varchar) TableB: dts_started (datetime) task_b (varchar) What I would like to do is determine how long a task took to complete. The join parameter would be something like ON task_a = task_b AND dts_completed < dts_started The issue is that there may be multiple date-times that occur after the dts_completed. How do I create a join that only returns the first tableB-datetime that occurs after the tableA-datetime?

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  • Nested loop traversing arrays

    - by alecco
    There are 2 very big series of elements, the second 100 times bigger than the first. For each element of the first series, there are 0 or more elements on the second series. This can be traversed and processed with 2 nested loops. But the unpredictability of the amount of matching elements for each member of the first array makes things very, very slow. The actual processing of the 2nd series of elements involves logical and (&) and a population count. I couldn't find good optimizations using C but I am considering doing inline asm, doing rep* mov* or similar for each element of the first series and then doing the batch processing of the matching bytes of the second series, perhaps in buffers of 1MB or something. But the code would be get quite messy. Does anybody know of a better way? C preferred but x86 ASM OK too. Many thanks! Sample/demo code with simplified problem, first series are "people" and second series are "events", for clarity's sake. (the original problem is actually 100m and 10,000m entries!) #include <stdio.h> #include <stdint.h> #define PEOPLE 1000000 // 1m struct Person { uint8_t age; // Filtering condition uint8_t cnt; // Number of events for this person in E } P[PEOPLE]; // Each has 0 or more bytes with bit flags #define EVENTS 100000000 // 100m uint8_t P1[EVENTS]; // Property 1 flags uint8_t P2[EVENTS]; // Property 2 flags void init_arrays() { for (int i = 0; i < PEOPLE; i++) { // just some stuff P[i].age = i & 0x07; P[i].cnt = i % 220; // assert( sum < EVENTS ); } for (int i = 0; i < EVENTS; i++) { P1[i] = i % 7; // just some stuff P2[i] = i % 9; // just some other stuff } } int main(int argc, char *argv[]) { uint64_t sum = 0, fcur = 0; int age_filter = 7; // just some init_arrays(); // Init P, P1, P2 for (int64_t p = 0; p < PEOPLE ; p++) if (P[p].age < age_filter) for (int64_t e = 0; e < P[p].cnt ; e++, fcur++) sum += __builtin_popcount( P1[fcur] & P2[fcur] ); else fcur += P[p].cnt; // skip this person's events printf("(dummy %ld %ld)\n", sum, fcur ); return 0; } gcc -O5 -march=native -std=c99 test.c -o test

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