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• Iterating through Event Log Entry Collection, IndexOutOutOfBoundsException

  - by fjdumont

  Hello, in a service application I am iterating through the Windows application event log to parse Events in order react depanding on the entry message. In the case that the event log is full (Windows usually makes sure there is enough space by deleting old entries - this is configurable in the eventvwr.exe settings), the service always runs into an IndexOutOfBoundsException while iterating through the EventLog.Entries collection. No matter how I iterate (for-loop, using the collections enumerator, copying the collection into an array, ...), I can't seem to get rid of this ´bug´. Currently, I ensure that the log is not full in order to keep the service running by regularly deleting the last few item by parsing the event log file and deleting the last few nodes (Don't beat me up, I couldn't find a better alternative...). How can I iterate through the collection without trying to access already deleted entries? Is there probably a more elegant method? I am only trying to acces the logs written during the last x seconds (even LINQ failed to select those when the log is full - same exception), could this help? Thanks for any advice and hints Frank Edit: I forgot to mention that my assumption is the loops are accessing entries which are being deleted during iteration by Windows. Basically that is why I tried to clone the collection. Is there perhaps a way to lock the collection for a small amount of time for just my application?

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• Code promotion: Enforcing the rules

  - by jbarker7

  So here is our problem: We have a small team of developers with their own ways of doing things-- I am trying to formalize a process in which we are required to promote our code in the following order: Local sandbox Dev UAT Staging Live Developers develop/test as they go on their own sandbox, Dev is its own box that we would use for continuous integration, UAT is another site in IIS on the dev box, which uses our dev database. We then promote to staging, which is a site in IIS on the Live box and using live data (just like the live, hence staging). Then, finally, we promote to live. Here are a few of my questions: 1.) Does this seem to be best practice? If not, what needs to be done differently? 2.) How do I enforce the rules to the developers? Often developers skip steps in order to save time... this should not be tolerated and would be great if it could be physically enforced. 3.) How do I enforce these rules to the business group? The business group just wants to get features out FAST. Do we promote only on certain days? Thanks! Josh

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• breadth-first traversal of directory tree is not lazy

  - by user855443

  I try to traverse the diretory tree. A naive depth-first traversal seems not to produce the data in a lazy fashion and runs out of memory. I next tried a breadth first approach, which shows the same problem - it uses all the memory available and then crashes. the code i have is: getFilePathBreadtFirst :: FilePath -> IO [FilePath] getFilePathBreadtFirst fp = do fileinfo <- getInfo fp res :: [FilePath] <- if isReadableDirectory fileinfo then do children <- getChildren fp lower <- mapM getFilePathBreadtFirst children return (children ++ concat lower) return (children ++ concat () else return [fp] -- should only return the files? return res getChildren :: FilePath -> IO [FilePath] getChildren path = do names <- getUsefulContents path let namesfull = map (path </>) names return namesfull testBF fn = do -- crashes for /home/frank, does not go to swap fps <- getFilePathBreadtFirst fn putStrLn $ unlines fps I think all the code is either linear or tail recursive, and I would expect that the listing of filenames starts immediately, but in fact it does not. Where is the error in my code and my thinking? where have I lost lazy evaluation?

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• Queries within queries: Is there a better way?

  - by mririgo

  As I build bigger, more advanced web applications, I'm finding myself writing extremely long and complex queries. I tend to write queries within queries a lot because I feel making one call to the database from PHP is better than making several and correlating the data. However, anyone who knows anything about SQL knows about JOINs. Personally, I've used a JOIN or two before, but quickly stopped when I discovered using subqueries because it felt easier and quicker for me to write and maintain. Commonly, I'll do subqueries that may contain one or more subqueries from relative tables. Consider this example: SELECT (SELECT username FROM users WHERE records.user_id = user_id) AS username, (SELECT last_name||', '||first_name FROM users WHERE records.user_id = user_id) AS name, in_timestamp, out_timestamp FROM records ORDER BY in_timestamp Rarely, I'll do subqueries after the WHERE clause. Consider this example: SELECT user_id, (SELECT name FROM organizations WHERE (SELECT organization FROM locations WHERE records.location = location_id) = organization_id) AS organization_name FROM records ORDER BY in_timestamp In these two cases, would I see any sort of improvement if I decided to rewrite the queries using a JOIN? As more of a blanket question, what are the advantages/disadvantages of using subqueries or a JOIN? Is one way more correct or accepted than the other?

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• Moving to an arbitrary position in a file in Python

  - by B Rivera

  Let's say that I routinely have to work with files with an unknown, but large, number of lines. Each line contains a set of integers (space, comma, semicolon, or some non-numeric character is the delimiter) in the closed interval [0, R], where R can be arbitrarily large. The number of integers on each line can be variable. Often times I get the same number of integers on each line, but occasionally I have lines with unequal sets of numbers. Suppose I want to go to Nth line in the file and retrieve the Kth number on that line (and assume that the inputs N and K are valid --- that is, I am not worried about bad inputs). How do I go about doing this efficiently in Python 3.1.2 for Windows? I do not want to traverse the file line by line. I tried using mmap, but while poking around here on SO, I learned that that's probably not the best solution on a 32-bit build because of the 4GB limit. And in truth, I couldn't really figure out how to simply move N lines away from my current position. If I can at least just "jump" to the Nth line then I can use .split() and grab the Kth integer that way. The nuance here is that I don't just need to grab one line from the file. I will need to grab several lines: they are not necessarily all near each other, the order in which I get them matters, and the order is not always based on some deterministic function. Any ideas? I hope this is enough information. Thanks!

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• Matab - Trace contour line between two different points

  - by Graham

  Hi, I have a set of points represented as a 2 row by n column matrix. These points make up a connected boundary or edge. I require a function that traces this contour from a start point P1 and stop at an end point P2. It also needs to be able trace the contour in a clockwise or anti-clockwise direction. I was wondering if this can be achieved by using some of matlabs functions. I have tried to write my own function but this was riddled with bugs and I have also tried using bwtraceboundary and indexing however this has problematic results as the points within the matrix are not in the order that create the contour. Thank you in advance for any help. Btw, I have included a link to a plot of the set of points. It is half the outline of a hand. The function would ideally trace the contour from ether the red star to the green triangle. Returning the points in order of traversal.

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• Drupal advanced ACLs for "untrusted" administrators

  - by redShadow

  I have a multi-site Drupal-6 installation containing websites of different customers. On each site, there is an "administrator" role that includes mainly the customer's account. We want to give as many permissions as possible to this privileged user, but this could bring to security leaks using just the Drupal Core permissions management system. The main thing to avoid is the customer account being able to run PHP code on the server (that would be like being logged on the server as the www-data user.. sounds really bad). To avoid that, it is not sufficient to deny PHP code evaluation for the role. Since the administrator role must have permissions to manage users, he could also change the password of the user #1 and login in the site as superadmin. The second goal would be to deny also some "confusing" administrative pages (such as module selection) but not others (such as site informations configuration, or theme selection, etc.) I found the User One module that seems to fix the first problem, but I have no idea on how to solve the second one. I found some modules around, but no-one seems to fit.. it seems like the most ACLs are thought to protect the content, and not the site itself, as if the site administrator would always be the server owner itself..

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• Getting the first of a GROUP BY clause in SQL

  - by Michael Bleigh

  I'm trying to implement single-column regionalization for a Rails application and I'm running into some major headaches with a complex SQL need. For this system, a region can be represented by a country code (e.g. us) a continent code that is uppercase (e.g. NA) or it can be NULL indicating the "default" information. I need to group these items by some relevant information such as a foreign key (we'll call it external_id). Given a country and its continent, I need to be able to select only the most specific region available. So if records exist with the country code, I select them. If, not I want a records with the continent code. If not that, I want records with a NULL code so I can receive the default values. So far I've figured that I may be able to use a generated CASE statement to get an arbitrary sort order. Something like this: SELECT *, CASE region WHEN 'us' THEN 1 WHEN 'NA' THEN 2 ELSE 3 END AS region_sort FROM my_table WHERE region IN ('us','NA') OR region IS NULL GROUP BY external_id ORDER BY region_sort The problem is that without an aggregate function the actual data returned by the GROUP BY for a given row seems to be untameable. How can I massage this query to make it return only the first record of the region_sort ordered groups?

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• Summing Row in SQL query for time range

  - by user3703334

  I'm trying to group a large amount of data into smaller bundles. Currently the code for my query is as follows SELECT [DateTime] ,[KW] FROM [POWER] WHERE datetime >= '2014-04-14 06:00:00' and datetime < '2014-04-21 06:00:00' ORDER BY datetime which gives me DateTime KW 4/14/2014 6:00:02.0 1947 4/14/2014 6:00:15.0 1946 4/14/2014 6:00:23.0 1947 4/14/2014 6:00:32.0 1011 4/14/2014 6:00:43.0 601 4/14/2014 6:00:52.0 585 4/14/2014 6:01:02.0 582 4/14/2014 6:01:12.0 580 4/14/2014 6:01:21.0 579 4/14/2014 6:01:32.0 579 4/14/2014 6:01:44.0 578 4/14/2014 6:01:53.0 578 4/14/2014 6:02:01.0 577 4/14/2014 6:02:12.0 577 4/14/2014 6:02:22.0 577 4/14/2014 6:02:32.0 576 4/14/2014 6:02:42.0 578 4/14/2014 6:02:52.0 577 4/14/2014 6:03:02.0 577 4/14/2014 6:03:12.0 577 4/14/2014 6:03:22.0 578 . . . . 4/21/2014 5:59:55.0 11 Now there is a reading every 10 seconds from a substation. Now I want to group this data into hourly readings. Thus 00:00-01:00 = sum([KW]] for where datetime >= '^date^ 00:00:00' and datetime < '^date^ 01:00:00' I've tried using a convert to change the datetime into date and time field and then only to add all the time fields together with no success. Can someone please assist me, I'm not sure what is right way of doing this. Thanks ADDED Ok so the spilt between Datetime is working nicely, but as if I add a SUM([KW]) function SQL gives an error. And if I include any of the group functions it also nags. Below is what works, I still need to sum the KW per the grouping of hours. I've tried using Group By Hour and Group by DATEPART(Hour,[DateTime]) Both didn't work. SELECT DATEPART(Hour,[DateTime]) Hour ,DATEPART(Day,[DateTime]) Day ,DATEPART(Month,[DateTime]) Month ,([KVAReal]) ,([KVAr]) ,([KW]) FROM [POWER].[dbo].[IT10t_PAC3200] WHERE datetime >= '2014-04-14 06:00:00' and datetime < '2014-04-21 06:00:00' order by datetime

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• connecting to secure database from website host

  - by jim

  Hello all, I've got a requirement to both read and write data via a .net webservice to a sqlserver database that's on a private network. this database is currently accessed via a vpn connection by remote client software (on standard desktop machines) to get latest product prices and to upload product stock sales. I've been tasked with finding a way to centralise this access from a webservice that the clients then access, rather than them using the vpn route to connect directly to the database. My question is related to my .net service's relationship to the sqlserver database. What are the options for connecting to a private network vpn from a domain host in order to achive the functionality of allowing the webservice to both read and write data to the database. For now, I'm not too concerned about the client connectivity and security (tho i appreciate that this will have to be worked out too), I'm really just interested in discovering the options available in order to allow my .net webservice to connect to the private network in as painless and transparent a way as posible. The option of switching the database onto public hosting is not an option, so I have to work with the sdcenario as described above for now, unless there's a compelling rationale presented to do otherwise. thanks all... jim

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• MySQL SELECT combining 3 SELECTs INTO 1

  - by Martin Tóth

  Consider following tables in MySQL database: entries: creator_id INT entry TEXT is_expired BOOL other: creator_id INT entry TEXT userdata: creator_id INT name VARCHAR etc... In entries and other, there can be multiple entries by 1 creator. userdata table is read only for me (placed in other database). I'd like to achieve a following SELECT result: +------------+---------+---------+-------+ | creator_id | entries | expired | other | +------------+---------+---------+-------+ | 10951 | 59 | 55 | 39 | | 70887 | 41 | 34 | 108 | | 88309 | 38 | 20 | 102 | | 94732 | 0 | 0 | 86 | ... where entries is equal to SELECT COUNT(entry) FROM entries GROUP BY creator_id, expired is equal to SELECT COUNT(entry) FROM entries WHERE is_expired = 0 GROUP BY creator_id and other is equal to SELECT COUNT(entry) FROM other GROUP BY creator_id. I need this structure because after doing this SELECT, I need to look for user data in the "userdata" table, which I planned to do with INNER JOIN and select desired columns. I solved this problem with selecting "NULL" into column which does not apply for given SELECT: SELECT creator_id, COUNT(any_entry) as entries, COUNT(expired_entry) as expired, COUNT(other_entry) as other FROM ( SELECT creator_id, entry AS any_entry, NULL AS expired_entry, NULL AS other_enry FROM entries UNION SELECT creator_id, NULL AS any_entry, entry AS expired_entry, NULL AS other_enry FROM entries WHERE is_expired = 1 UNION SELECT creator_id, NULL AS any_entry, NULL AS expired_entry, entry AS other_enry FROM other ) AS tTemp GROUP BY creator_id ORDER BY entries DESC, expired DESC, other DESC ; I've left out the INNER JOIN and selecting other columns from userdata table on purpose (my question being about combining 3 SELECTs into 1). Is my idea valid? = Am I trying to use the right "construction" for this? Are these kind of SELECTs possible without creating an "empty" column? (some kind of JOIN) Should I do it "outside the DB": make 3 SELECTs, make some order in it (let's say python lists/dicts) and then do the additional SELECTs for userdata? Solution for a similar question does not return rows where entries and expired are 0. Thank you for your time.

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• How can I pass in a params of Expression<Func<T, object>> to a method?

  - by Pure.Krome

  Hi folks, I have the following two methods :- public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params string[] associations) { ... } public static IQueryable<T> IncludeAssociations<T>(this IQueryable<T> source, params Expression<Func<T, object>>[] expressions) { ... } Now, when I try and pass in a params of Expression<Func<T, object>>[], it always calls the first method (the string[]' and of course, that value isNULL`) Eg. Expression<Func<Order, object>> x1 = x => x.User; Expression<Func<Order, object>> x2 = x => x.User.Passport; var foo = _orderRepo .Find() .IncludeAssociations(new {x1, x2} ) .ToList(); Can anyone see what I've done wrong? Why is it thinking my params are a string? Can I force the type, of the 2x variables?

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• Which database I can used and relationship in it ??

  - by mimo-hamad

  My projece make me confused which I didn't find clear things that make me understand the required database and the relationships in it So, would a super one help me to solve it ?!! ;D this is required: 1) Model the data stored in the database (Identify the entities, roles, relationships, constraints, etc.) 2) Write the Oracle commands to create the database, find appropriate data, and populate the database 3) Write five different queries on your database, using the SELECT/FROM/WHERE construct provided in SQL. Your five queries should illustrate several different aspects of database querying, such as: a. Queries over more than one relation (by listing more than one relation in the FROM clause) b. Queries involving aggregate functions, such as SUM, COUNT, and AVG c. Queries involving complicated selects and joins d. Queries involving GROUP BY, HAVING or other similar functions. e. Queries that require the use of the DISTINCT keyword. And this the condition that we need to determine it to solve the required Q's above : 5) It is desired to develop an Internet membership club to buy products at special prices online. To join, new members must be referred by another existing member of the club. The system will keep the following information for each member: The member ID, referring member, birth date, member name, address, phone, mobile, credit card type, number and expiration date. The items are always shipped to the member's address noted in the membership application. The shipping fees will differ for each order.For each item to be requested, the member will select an item from a long list of possible items. For each item in the database, we store an item ID, an item name, description, and list price. The list price will be different from the actual sale price. The available quantity and the back-ordered quantity (the back-ordered quantity is the quantity on-order by the club from its suppliers) is also noted

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• Maven3 Issues with building a multi-module enterprise project

  - by Sujit K

  I just migrated from Maven2 to Maven3 and I'm able to build each module individually or all the modules in one shot by calling mvn clean install. However, in Maven2, since we have multi-module enterprise project, we build multiple ear's and each ear is built as its own module with its own child pom. To build an individual ear with its dependents, the below command works fine in Maven2 but not in Maven3. Let me explain the issue in Maven3 a bit later. mvn -pl ear_module -rf first_dependent_module -am clean install In Maven2 when the reactor lists the build order, I see first_dependent_module second_dependent_module ear_module End of the day I have my ear module also part of the reactor which is how it should be. The reason we call -rf is we don't want to delete the target folder at the main ${project.basedir} (so not to delete the output created in target from building the other ear modules). With Maven3, however, this is all I see when the reactor lists the build order: first_dependent_module second_dependent_module Maven3 totally ignores the argument (ear_module) set to -pl flag to be also built after its dependents have been. Not sure what I'm missing here. Any help/tips would be greatly appreciated. P.S: The build I'm making is similar to the one below.... Build specific module in multi-module project Thanks, SK

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• Product Name Print Several times, How to fix.?

  - by mans

  i had added the following Opencart module for my order report list... http://www.opencart.com/index.php?route=extension/extension/info&extension_id=3597&filter_search=order%20list%20filter%20model&page=4 I have problems with the column "Products". If there are more than one option the products name prints several times. So if I got a product with three options the product name prints three times. Is there any way to fix this problem? i want print product name and model number only once, any idea.? i will attach the results what i got now... this is my sql query... public function getOrders($data = array()) { $sql = "select o.order_id,o.email,o.telephone,CONCAT(o.shipping_address_1, ' ', o.shipping_address_2) AS address,CONCAT(o.firstname, ' ', o.lastname) AS customer,o.payment_zone AS state,o.payment_address_2 AS block, o.payment_address_1 AS address,o.payment_postcode AS postcode,(SELECT os.name FROM " . DB_PREFIX . "order_status os WHERE os.order_status_id = o.order_status_id AND os.language_id = '" . (int)$this->config->get('config_language_id') . "') AS status,o.payment_city AS city,GROUP_CONCAT(pd.name) AS pdtname,GROUP_CONCAT(op.model) AS model,o.date_added,sum(op.quantity) AS quantity,GROUP_CONCAT(opt.value ) AS options, GROUP_CONCAT(opt.order_product_id ) AS ordprdid,GROUP_CONCAT(op.order_product_id ) AS optprdid, GROUP_CONCAT(op.quantity) AS opquantity from `" . DB_PREFIX . "order` o LEFT JOIN " . DB_PREFIX . "order_product op ON (op.order_id = o.order_id) LEFT JOIN " . DB_PREFIX . "product_description pd ON (pd.product_id = op.product_id and pd.language_id = '" . (int)$this->config->get('config_language_id') . "') LEFT JOIN " . DB_PREFIX . "order_option opt ON (opt.order_product_id = op.order_product_id) "; Product Name = GROUP_CONCAT(pd.name) AS pdtname,

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• JQuery tablesorter - Second click on column header doesn't resort

  - by Jonathan

  I'm using tablesorter in on a table I added to a view in django's admin (although I'm not sure this is relevant). I'm extending the html's header: {% block extrahead %} <script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.js"></script> <script type="text/javascript" src="http://mysite.com/media/tablesorter/jquery.tablesorter.js"></script> <script type="text/javascript"> $(document).ready(function() { $("#myTable").tablesorter(); } ); </script> {% endblock %} When I click on a column header, it sorts the table using this column in descending order - that's ok. When I click the same column header a second time - it does not reorder to ascending order. What's wrong with it? the table's html looks like: <table id="myTable" border="1"> <thead> <tr> <th>column_name_1</th> <th>column_name_2</th> <th>column_name_3</th> </tr> </thead> <tbody> {% for item in extra.items %} <tr> <td>{{ item.0|safe }} </td> <td>{{ item.1|safe }} </td> <td>{{ item.2|safe }} </td> </tr> {% endfor %} </tbody> </table>

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• pyPDF - Retrieve page numbers from document

  - by SquidneyPoitier

  At the moment I'm looking into doing some PDF merging with pyPdf, but sometimes the inputs are not in the right order, so I'm looking into scraping each page for its page number to determine the order it should go in (e.g. if someone split up a book into 20 10-page PDFs and I want to put them back together). I have two questions - 1.) I know that sometimes the page number is stored in the document data somewhere, as I've seen PDFs that render on Adobe as something like [1243] (10 of 150), but I've read documents of this sort into pyPDF and I can't find any information indicating the page number - where is this stored? 2.) If avenue #1 isn't available, I think I could iterate through the objects on a given page to try to find a page number - likely it would be its own object that has a single number in it. However, I can't seem to find any clear way to determine the contents of objects. If I run: pdf.getPage(0).getContents() This usually either returns: {'/Filter': '/FlateDecode'} or it returns a list of IndirectObject(num, num) objects. I don't really know what to do with either of these and there's no real documentation on it as far as I can tell. Is anyone familiar with this kind of thing that could point me in the right direction?

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• question about counting sort

  - by davit-datuashvili

  hi i have write following code which prints elements in sorted order only one big problem is that it use two additional array here is my code public class occurance{ public static final int n=5; public static void main(String[]args){ // n is maximum possible value what it should be in array suppose n=5 then array may be int a[]=new int[]{3,4,4,2,1,3,5};// as u see all elements are less or equal to n //create array a.length*n int b[]=new int[a.length*n]; int c[]=new int[b.length]; for (int i=0;i<b.length;i++){ b[i]=0; c[i]=0; } for (int i=0;i<a.length;i++){ if (b[a[i]]==1){ c[a[i]]=1; } else{ b[a[i]]=1; } } for (int i=0;i<b.length;i++){ if (b[i]==1) { System.out.println(i); } if (c[i]==1){ System.out.println(i); } } } } // 1 2 3 3 4 4 5 1.i have two question what is complexity of this algorithm?i mean running time 2. how put this elements into other array with sorted order? thanks

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• MySQL Paritioning performance

  - by Imran Pathan

  Measured performance on key partitioned tables and normal tables separately. But we couldn't find any performance improvement with partitioning. Queries are pruned. Using MySQL 5.1.47 on RHEL 4. Table details: UserUsage - Will have entries for user mobile number and data usage for each date. Mobile number and Date as PRI KEY. UserProfile - Queries prev table and stores summary for each mobile number. Mobile number PRI KEY. CREATE TABLE `UserUsage` ( `Msisdn` decimal(20,0) NOT NULL, `Date` date NOT NULL, . . PRIMARY KEY USING BTREE (`Msisdn`,`Date`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 PARTITION BY KEY(Msisdn) PARTITIONS 50; CREATE TABLE `UserProfile` ( `Msisdn` decimal(20,0) NOT NULL, . . PRIMARY KEY (`Msisdn`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 PARTITION BY KEY(Msisdn) PARTITIONS 50; Second table is updated by query select and order by date in first table in a perl program, query is select * from UserUsage where Msisdn=number order by Date desc limit 7 [Process data in perl] update UserProfile values(....) where Msisdn=number explain partition for select, shows row being scanned in a particular partition only. Is something wrong with partition design or queries as partitioning is taking almost same or more time compared to normal tables?

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• Where does java.util.logging.Logger store their log

  - by Harry Pham

  This might be a stupid question but I am a bit lost with java Logger private static Logger logger = Logger.getLogger("order.web.OrderManager"); logger.info("Removed order " + id + "."); Where do I see the log? Also this quote from java.util.logging.Logger library: On each logging call the Logger initially performs a cheap check of the request level (e.g. SEVERE or FINE) against the effective log level of the logger. If the request level is lower than the log level, the logging call returns immediately. After passing this initial (cheap) test, the Logger will allocate a LogRecord to describe the logging message. It will then call a Filter (if present) to do a more detailed check on whether the record should be published. If that passes it will then publish the LogRecord to its output Handlers. Does this mean that if I have 3 request level log: logger.log(Level.FINE, "Something"); logger.log(Level.WARNING, "Something"); logger.log(Level.SEVERE, "Something"); And my log level is SEVERE, I can see all three logs, if my log level is WARNING, then I cant see SEVERE log, is that correct? And how do I set the log level?

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• (Oracle) How get total number of results when using a pagination query?

  - by BestPractices

  I am using Oracle 10g and the following paradigm to get a page of 15 results as a time (so that when the user is looking at page 2 of a search result, they see records 16-30). select * from ( select rownum rnum, a.* from (my_query) a where rownum <= 30 ) where rnum > 15; Right now I'm having to run a separate SQL statement to do a "select count" on "my_query" in order to get the total number of results for my_query (so that I can show it to the user and use it to figure out total number of pages, etc). Is there any way to get the total number of results without doing this via a second query, i.e. by getting it from above query? I've tried adding "max(rownum)", but it doesn't seem to work (I get an error [ORA-01747] that seems to indicate it doesnt like me having the keyword rownum in the group by). My rationale for wanting to get this from the original query rather than doing it in a separate SQL statement is that "my_query" is an expensive query so I'd rather not run it twice (once to get the count, and once to get the page of data) if I dont have to; but whatever solution I can come up with to get the number of results from within a single query (and at the same time get the page of data I need) should not add much if any additional overhead, if possible. Please advise. Here is exactly what I'm trying to do for which I receive an ORA-01747 error because I believe it doesnt like me having ROWNUM in the group by. Note, If there is another solution that doesnt use max(ROWNUM), but something else, that is perfectly fine too. This solution was my first thought as to what might work. SELECT * FROM (SELECT r.*, ROWNUM RNUM, max(ROWNUM) FROM (SELECT t0.ABC_SEQ_ID AS c0, t0.FIRST_NAME, t0.LAST_NAME, t1.SCORE FROM ABC t0, XYZ t1 WHERE (t0.XYZ_ID = 751) AND t0.XYZ_ID = t1.XYZ_ID ORDER BY t0.RANK ASC) r WHERE ROWNUM <= 30 GROUP BY r.*, ROWNUM) WHERE RNUM > 15

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• How do I build a filtered_streambuf based on basic_streambuf?

  - by swestrup

  I have a project that requires me to insert a filter into a stream so that outgoing data will be modified according to the filter. After some research, it seems that what I want to do is create a filtered_streambuf like this: template <class StreamBuf class filtered_streambuf: public StreamBuf { ... } And then insert a filtered_streambuf<> into whichever stream I need to be filtered. My problem is that I don't know what invariants I need to maintain while filtering a stream, in order to ensure that Derived classes can work as expected. In particular, I may find I have filtered_streambufs built over other filtered_streambufs. All the various stream inserters, extractors and manipulators work as expected. The trouble is that I just can't seem to work out what the minimal interface is that I need to supply in order to guarantee that an iostream will have what it needs to work correctly. In particular, do I need to fake the movement of the protected pointer variables, or not? Do I need a fake data buffer, or not? Can I just override the public functions, rewriting them in terms of the base streambuf, or is that too simplistic?

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• How to get acts on taggable working

  - by Schipperius

  I am new to ruby on rails (and programming) and this is probably a really stupid question. I am using Rails 3.2 and trying to use acts_as_taggable_on to generate tags on articles and to have those tags show on article index and show pages as a clickable links. I have tags clickable on both the article show and index pages, but the links just go back to the index page and don't sort according to the tag name. I have scoured the Internet and pieced together the code below from various sources, but I am clearly missing something. Any help is greatly appreciated, as I have exhausted my seemingly limited knowledge! Thanks. Here is what I have: class ArticlesController < ApplicationController def tagged @articles = Article.all(:order => 'created_at DESC') @tags = Article.tag_counts_on(:tags) @tagged_articles = Article.tagged_with(params[:tags]) respond_to do |format| format.html # index.html.erb format.json { render :json => @articles } end end def index @article = Article.new @articles = Article.paginate :page => params[:page], :per_page => 3 @tags = Article.tag_counts_on(:tags) respond_to do |format| format.html # index.html.erb format.json { render json: @articles } end end module ArticlesHelper include ActsAsTaggableOn::TagsHelper end class Article < ActiveRecord::Base acts_as_ordered_taggable acts_as_ordered_taggable_on :tags, :location, :about attr_accessible :tag_list scope :by_join_date, order("created_at DESC") end article/index.html.erb <% tag_cloud(@tags, %w(tag1 tag2 tag3 tag4)) do |tag| %> <%= link_to tag.name, articles_path(:id => tag.name) %> <% end %> article/show.html.erb <%= raw @article.tags.map { |tag| link_to tag.name, articles_path(:tag_id => tag) }.join(" | ") %>

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• directory resource does not create directory

  - by Dan Tenenbaum

  I have a Vagrantfile that provisions a VM by running a chef recipe. The first resource in the chef recipe is: directory "/downloads" do owner "root" group "root" mode "0755" action :create end # check that it worked: raise "/downloads doesn't exist!" unless File.exists? "/downloads" When I run this at work, it works fine. When I run it at home, it fails, the exception is raised when I check to see if /downloads exists. I'm not sure why this is happening. I would expect it to behave identically, since the underlying Vagrant box is the same both at work and at home. I am a chef newb so perhaps there is something I am not understanding about the order in which the resources are run within my recipe? I would expect them to run in sequential order... I also tried putting a notifies call inside the directory block, where I call another execute block :immediately. That works, but inside the second execute block I test to see whether /downloads has been created and it hasn't. Clearly I'm missing something very basic.

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• Which templating languages output HTML *as a tree of nodes*?

  - by alamar

  HTML is a tree of nodes, before all. It's not just a text. However, most templating engines handle their input and output as it was just a text; they don't care what happens around their tags, their {$foo}'s and <% bar() %>'s; also they don't care about what are they outputting. Sometimes they happen to produce a correct html, but that's just a coincidence; they didn't aim for that, all they wanted is to replace some funny marks in the text stream with their evaluation. There are a few templating engines which do treat their output as a set of nodes; XSLT and Haml come to mind. For some tasks, this has advantages: for example, you can automatically reformat (like, delete all empty text nodes; auto-indent; word-wrap). The result is guaranteed to be a correct xml/sgml unless you use a strict subset of operations that can break that. Also, such templating engine would automatically quote strings, differently in text nodes and in attributes, because it strictly knows whether you're writing an attribute or a text node. Moreover, it can conditionally remove a node from output because it knows where it does begin and end, which is useful, and do other non-trivial node operations. You might not like XSLT for its verbosiness or functionalness, but it's damn helps that your template is xmllint-able XML, and your output is a good sgml/xml. So the question is: Which template engines do you know that treat their output as a set of correct nodes, not just an unstructured text? I know XSLT, Haml and some obscure python-based one. Moar!

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