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• Google GWT cross-browser support: is it BS ?

  - by Tim

  I developed a browser-deployed full-text search app in FlashBuilder which communicates RESTfully with a remote web-server. The software fits into a tiny niche--it is for use with ancient languages not modern ones, and there's no way I'm going to make any money on it but I did spend a lot of time on it. Now that Apple won't allow Flash on the iPad, I'm looking for a 100% javascript solution and was led to consider GWT. It looked promising, but one of the apps being "showcased" as a stellar example of what can be done with GWT has this disclaimer on their website (names {removed} to protect the potentially innocent) : Your current web browser (Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1045 Safari/532.5) is not officially supported by {company and product name were here}. If you experience any problems using this site please install either Microsoft Internet Explorer 6+ or Mozilla Firefox 3.5+ before contacting {product name was here} Support. What gives when GWT apps aren't "officially" supported on Chrome? What grade (A, B, C, D, F) would you give to GWT for cross-browser support? For folks who don't get these kinds of letter grades, A is "excellent" and "F" is failure, and "C" is average. Thanks for your opinions.

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• New Perl user: using a hash of arrays

  - by Zach H

  I'm doing a little datamining project where a perl script grabs info from a SQL database and parses it. The data consists of several timestamps. I want to find how many of a particular type of timestamp exist on any particular day. Unfortunately, this is my first perl script, and the nature of perl when it comes to hashes and arrays is confusing me quite a bit. Code segment: my %values=();#A hash of the total values of each type of data of each day. #The key is the day, and each key stores an array of each of the values I need. my @proposal; #[drafted timestamp(0), submitted timestamp(1), attny approved timestamp(2),Organiziation approved timestamp(3), Other approval timestamp(4), Approved Timestamp(5)] while(@proposal=$sqlresults->fetchrow_array()){ #TODO: check to make sure proposal is valid #Increment the number of timestamps of each type on each particular date my $i; for($i=0;$i<=5;$i++) $values{$proposal[$i]}[$i]++; #Update rolling average of daily #TODO: To check total load, increment total load on all dates between attourney approve date and accepted date for($i=$proposal[1];$i<=$proposal[2];$i++) $values{$i}[6]++; } I keep getting syntax errors inside the for loops incrementing values. Also, considering that I'm using strict and warnings, will Perl auto-create arrays of the right values when I'm accessing them inside the hash, or will I get out-of bounds errors everywhere? Thanks for any help, Zach

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• How to stop MVC caching the results of invoking and action method?

  - by Trey Carroll

  I am experiencing a problem with IE caching the results of an action method. Other articles I found were related to security and the [Authorize] attribute. This problem has nothing to do with security. This is a very simple "record a vote, grab the average, return the avg and the number of votes" method. The only slightly interesting thing about it is that it is invoked via Ajax and returns a Json object. I believe that it is the Json object that is getting catched. When I run it from FireFox and watch the XHR traffic with Firebug, everything works perfectly. However, under IE 8 the "throbber" graphic doesn't ever have time to show up and the page elements that display the "new" avg and count that are being injected into the page with jQuery are never different. I need a way to tell MVC to never cache this action method. This article seems to address the problem, but I cannot understand it: http://stackoverflow.com/questions/1441467/prevent-caching-of-attributes-in-asp-net-mvc-force-attribute-execution-every-tim I need a bit more context for the solution to understand how to extend AuthorizationAttribute. Please address your answer as if you were speaking to someone who lacks a deep understanding of MVC even if that means replying with an article on some basics/prerequisites that are required. Thanks, Trey Carroll

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• Calculate car filled up times

  - by Ivan

  Here is the question: The driving distance between Perth and Adelaide is 1996 miles. On the average, the fuel consumption of a 2.0 litre 4 cylinder car is 8 litres per 100 kilometres. The fuel tank capacity of such a car is 60 litres. Design and implement a JAVA program that prompts for the fuel consumption and fuel tank capacity of the aforementioned car. The program then displays the minimum number of times the car’s fuel tank has to be filled up to drive from Perth to Adelaide. Note that 62 miles is equal to 100 kilometres. What data will you use to test that your algorithm works correctly? Here is what I've done so far: import java.util.Scanner;// public class Ex4{ public static void main( String args[] ){ Scanner input = new Scanner( System.in ); double distance, consumption, capacity, time; distance = Math.sqrt(1996/62*100); consumption = Math.sqrt(8/100); capacity = 60; time = Math.sqrt(distance*consumption/capacity); System.out.println("The car's fuel tank need to be filled up:" + time + "times"); } } I can compile it but the problem is that the result is always 0.0, can anyone help me what's wrong with it ?

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• Can someone look over the curriculum for this major & give me your thoughts? Computing & Security Te

  - by scottsharpejr

  My goal is to become a good web developer. I'm interested in learning how to build complex websites as well as how to write web applications. I want skills that will enable me to write apps for <--insert hottest web trend here-- (Facebook & iphone apps for example) This is one of my goals as far as Tech. is concerned. I'd also like to have a brod knowledge of different areas of IT. I'm looking into majoring in "Computing & Security Technology". The program is offered by Drexel in conjunction with my CC. It's a 4 year degree. Can someone take a look @ the pdf below. It outlines every course I must take. http://www.drexelatbcc.org/academics/PDF/CST_CT.pdf For degree requirments w/ links to course descriptiongs see drexel.edu/catalog/degree/ct.htm With electives I can go up to Web Development 4. Based on my goals of Web development & wanting a well rounding education in information technology, what do you think of the curriculum? How will I fare entering the job market with this degree? My goals here are a little different. I'd like to work for 2 to 3 companies over the course of 6-7 years. Working with and learning different areas of IT. I'd like to stay with a company an average of 2-3 years before moving on. My end goal is to go into business for myself (IT related). I appreciate any and all advice the community here can give me! :) Could someone also explain to me their interpretation of this major? thanks! P.S. I already know XHTML & CSS. I am just now starting to experiment with PHP.

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• PostgreSQL: BYTEA vs OID+Large Object?

  - by mlaverd

  I started an application with Hibernate 3.2 and PostgreSQL 8.4. I have some byte[] fields that were mapped as @Basic (= PG bytea) and others that got mapped as @Lob (=PG Large Object). Why the inconsistency? Because I was a Hibernate noob. Now, those fields are max 4 Kb (but average is 2-3 kb). The PostgreSQL documentation mentioned that the LOs are good when the fields are big, but I didn't see what 'big' meant. I have upgraded to PostgreSQL 9.0 with Hibernate 3.6 and I was stuck to change the annotation to @Type(type="org.hibernate.type.PrimitiveByteArrayBlobType"). This bug has brought forward a potential compatibility issue, and I eventually found out that Large Objects are a pain to deal with, compared to a normal field. So I am thinking of changing all of it to bytea. But I am concerned that bytea fields are encoded in Hex, so there is some overhead in encoding and decoding, and this would hurt the performance. Are there good benchmarks about the performance of both of these? Anybody has made the switch and saw a difference?

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• Database Design Question regaurding duplicate information.

  - by galford13x

  I have a database that contains a history of product sales. For example the following table CREATE TABLE SalesHistoryTable ( OrderID, // Order Number Unique to all orders ProductID, // Product ID can be used as a Key to look up product info in another table Price, // Price of the product per unit at the time of the order Quantity, // quantity of the product for the order Total, // total cost of the order for the product. (Price * Quantity) Date, // Date of the order StoreID, // The store that created the Order PRIMARY KEY(OrderID)); The table will eventually have millions of transactions. From this, profiles can be created for products in different geographical regions (based on the StoreID). Creating these profiles can be very time consuming as a database query. For example. SELECT ProductID, StoreID, SUM(Total) AS Total, SUM(Quantity) QTY, SUM(Total)/SUM(Quantity) AS AvgPrice FROM SalesHistoryTable GROUP BY ProductID, StoreID; The above query could be used to get the Information based on products for any particular store. You could then determine which store has sold the most, has made the most money, and on average sells for the most/least. This would be very costly to use as a normal query run anytime. What are some design descisions in order to allow these types of queries to run faster assuming storage size isn’t an issue. For example, I could create another Table with duplicate information. Store ID (Key), Product ID, TotalCost, QTY, AvgPrice And provide a trigger so that when a new order is received, the entry for that store is updated in a new table. The cost for the update is almost nothing. What should be considered when given the above scenario?

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• Bored with CS. What can I study that will make an impact?

  - by Eric Martinez

  So I'm going to an average university, majoring in CS. I haven't learned a damn thing and am in my third year. I've come to be really bored with studying CS. Initially, I was kind of misinformed and thought majoring in CS would make me a good "product creator". I make my money combining programming and business/marketing. But I have always done programming for the love of the art. I find things like algorithms interesting and want to be able to use CS to solve real world problems. I like the idea of bioinformatics and other hybrid studies. I'm not good enough, yet I hope, to really make a significant effort in those areas but I aspire to be. What are some other fields, open problems, and otherwise cool stuff to apply CS knowledge to in the real world? I'm really looking for something that will motivate me and re-excite me to continue studying CS. Edit: Like someone mentioned below. I am very interesting in the idea of being able to use computer science to help answer fundamental questions of life and the universe. But I'm not sure what is possible or how to begin.

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• Problem with JMX query of Coherence node MBeans visible in JConsole

  - by Quinn Taylor

  I'm using JMX to build a custom tool for monitoring remote Coherence clusters at work. I'm able to connect just fine and query MBeans directly, and I've acquired nearly all the information I need. However, I've run into a snag when trying to query MBeans for specific caches within a cluster, which is where I can find stats about total number of gets/puts, average time for each, etc. The MBeans I'm trying to access programatically are visible when I connect to the remote process using JConsole, and have names like this: Coherence:type=Cache,service=SequenceQueue,name=SEQ%GENERATOR,nodeId=1,tier=back It would make it more flexible if I can dynamically grab all type=Cache MBeans for a particular node ID without specifying all the caches. I'm trying to query them like this: QueryExp specifiedNodeId = Query.eq(Query.attr("nodeId"), Query.value(nodeId)); QueryExp typeIsCache = Query.eq(Query.attr("type"), Query.value("Cache")); QueryExp cacheNodes = Query.and(specifiedNodeId, typeIsCache); ObjectName coherence = new ObjectName("Coherence:*"); Set<ObjectName> cacheMBeans = mBeanServer.queryMBeans(coherence, cacheNodes); However, regardless of whether I use queryMBeans() or queryNames(), the query returns a Set containing... ...0 objects if I pass the arguments shown above ...0 objects if I pass null for the first argument ...all MBeans in the Coherence:* domain (112) if I pass null for the second argument ...every single MBean (128) if I pass null for both arguments The first two results are the unexpected ones, and suggest a problem in the QueryExp I'm passing, but I can't figure out what the problem is. I even tried just passing typeIsCache or specifiedNodeId for the second parameter (with either coherence or null as the first parameter) and I always get 0 results. I'm pretty green with JMX — any insight on what the problem is? (FYI, the monitoring tool will be run on Java 5, so things like JMX 2.0 won't help me at this point.)

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• Submitting R jobs using PBS

  - by Tony

  I am submitting a job using qsub that runs parallelized R. My intention is to have R programme running on 4 different cores rather than 8 cores. Here are some of my settings in PBS file: #PBS -l nodes=1:ppn=4 .... time R --no-save < program1.R > program1.log I am issuing the command "ta job_id" and I'm seeing that 4 cores are listed. However, the job occupies a large amount of memory(31944900k used vs 32949628k total). If I were to use 8 cores, the jobs got hang due to memory limitation. top - 21:03:53 up 77 days, 11:54, 0 users, load average: 3.99, 3.75, 3.37 Tasks: 207 total, 5 running, 202 sleeping, 0 stopped, 0 zombie Cpu(s): 30.4%us, 1.6%sy, 0.0%ni, 66.8%id, 0.0%wa, 0.0%hi, 1.2%si, 0.0%st Mem: 32949628k total, 31944900k used, 1004728k free, 269812k buffers Swap: 2097136k total, 8360k used, 2088776k free, 6030856k cached Here is a snapshot when issuing command ta job_id PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1794 x 25 0 6247m 6.0g 1780 R 99.2 19.1 8:14.37 R 1795 x 25 0 6332m 6.1g 1780 R 99.2 19.4 8:14.37 R 1796 x 25 0 6242m 6.0g 1784 R 99.2 19.1 8:14.37 R 1797 x 25 0 6322m 6.1g 1780 R 99.2 19.4 8:14.33 R 1714 x 18 0 65932 1504 1248 S 0.0 0.0 0:00.00 bash 1761 x 18 0 63840 1244 1052 S 0.0 0.0 0:00.00 20016.hpc 1783 x 18 0 133m 7096 1128 S 0.0 0.0 0:00.00 python 1786 x 18 0 137m 46m 2688 S 0.0 0.1 0:02.06 R How can I prevent other users to use the other 4 cores? I like to mask somehow that my job is using 8 cores with 4 cores idling. Could anyone kindly help me out on this? Can this be solved using pbs? Many Thanks

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• What's the fastest way to bulk insert a lot of data in SQL Server (C# client)

  - by Andrew

  I am hitting some performance bottlenecks with my C# client inserting bulk data into a SQL Server 2005 database and I'm looking for ways in which to speed up the process. I am already using the SqlClient.SqlBulkCopy (which is based on TDS) to speed up the data transfer across the wire which helped a lot, but I'm still looking for more. I have a simple table that looks like this: CREATE TABLE [BulkData]( [ContainerId] [int] NOT NULL, [BinId] [smallint] NOT NULL, [Sequence] [smallint] NOT NULL, [ItemId] [int] NOT NULL, [Left] [smallint] NOT NULL, [Top] [smallint] NOT NULL, [Right] [smallint] NOT NULL, [Bottom] [smallint] NOT NULL, CONSTRAINT [PKBulkData] PRIMARY KEY CLUSTERED ( [ContainerIdId] ASC, [BinId] ASC, [Sequence] ASC )) I'm inserting data in chunks that average about 300 rows where ContainerId and BinId are constant in each chunk and the Sequence value is 0-n and the values are pre-sorted based on the primary key. The %Disk time performance counter spends a lot of time at 100% so it is clear that disk IO is the main issue but the speeds I'm getting are several orders of magnitude below a raw file copy. Does it help any if I: Drop the Primary key while I am doing the inserting and recreate it later Do inserts into a temporary table with the same schema and periodically transfer them into the main table to keep the size of the table where insertions are happening small Anything else? -- Based on the responses I have gotten, let me clarify a little bit: Portman: I'm using a clustered index because when the data is all imported I will need to access data sequentially in that order. I don't particularly need the index to be there while importing the data. Is there any advantage to having a nonclustered PK index while doing the inserts as opposed to dropping the constraint entirely for import? Chopeen: The data is being generated remotely on many other machines (my SQL server can only handle about 10 currently, but I would love to be able to add more). It's not practical to run the entire process on the local machine because it would then have to process 50 times as much input data to generate the output. Jason: I am not doing any concurrent queries against the table during the import process, I will try dropping the primary key and see if that helps. ~ Andrew

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• Is there a way to avoid spaghetti code over the years?

  - by Yoni Roit

  I've had several programming jobs. Each one with 20-50 developers, project going on for 3-5 years. Every time it's the same. Some programmers are bright, some are average. Everyone has their CS degree, everyone read design patterns. Intentions are good, people are trying hard to write good code but still after a couple of years the code turns into spaghetti. Changes in module A suddenly break module B. There are always these parts of code that no one can understand except for the person who wrote it. Changing infrastructure is impossible and backwards compatibility issues prevent good features to get in. Half of the time you just want to rewrite everything from scratch. And people more experienced than me treat this as normal. Is it? Does it have to be? What can I do to avoid this or should I accept it as a fact of life? Edit: Guys, I am impressed with the amount and quality of responses here. This site and its community rock!

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• DAL Layer : EF 4.0 or Normal Data access layer with Stored Procedure

  - by Harryboy

  Hello Experts, Application : I am working on one mid-large size application which will be used as a product, we need to decide on our DAL layer. Application UI is in Silverlight and DAL layer is going to be behind service layer. We are also moving ahead with domain model, so our DB tables and domain classes are not having same structure. So patterns like Data Mapper and Repository will definitely come into picture. I need to design DAL Layer considering below mentioned factors in priority manner Speed of Development with above average performance Maintenance Future support and stability of the technology Performance Limitation : 1) As we need to strictly go ahead with microsoft, we can not use NHibernate or any other ORM except EF 4.0 2) We can use any code generation tool (Should be Open source or very cheap) but it should only generate code in .Net, so there would not be any licensing issue on per copy basis. Questions I read so many articles about EF 4.0, on outset it looks like that it is still lacking in features from NHibernate but it is considerably better then EF 1.0 So, Do you people feel that we should go ahead with EF 4.0 or we should stick to ADO .Net and use any code geneartion tool like code smith or any other you feel best Also i need to answer questions like what time it will take to port application from EF 4.0 to ADO .Net if in future we stuck up with EF 4.0 for some features or we are having serious performance issue. In reverse case if we go ahead and choose ADO .Net then what time it will take to swith to EF 4.0 Lastly..as i was going through the article i found the code only approach (with POCO classes) seems to be best suited for our requirement as switching is really easy from one technology to other. Please share your thoughts on the same and please guide on the above questions

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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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• Teach Markup or use a WYSIWYG editor?

  - by Atomiton

  When it comes to WYSIWYG editors WYSI rarely WYG. The problem I always have is when people paste in formatted text from word. Ideally, what I'm looking for is a way for people to input text into the document while at the same time teaching them structure... I just don't know if that's a realistic goal ( compared to cut n' paste ) I'm curious if people have found using something other than WYSIWYG editors ( take SO, for example ) has worked for REAL WORLD USERS. I'm not talking about programmers, developers and experience internet users... I'm talking about your average user. I'd be interested in best practices when it comes to getting users to enter content... and I'd love it if someone could point me to some good editors/examples. there are lots of choices when it comes to WYSIWYG ( ckEditor, FreeTextBox, TinyMCE ) but I don't hear a lot about SO-like techniques. Does adding that small barrier scares users away? Is it too difficult to teach people to mark up their text? Is it easier to teach them html? Is a BBCode implementation a good idea? What are some Pros/Cons to wysiwyg/markup. What approach have others used?

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• ASP.NET webservice API security.

  - by Tejaswi Yerukalapudi

  Hi, I have an iPhone app accessing an ASP.NET Webservice for data. Since I'm building both the ASP.NET end and the iPhone part of the app, and we'll shortly be publishing it in the Appstore, I'd like to know what security checks I need to make. The basic flow of the program (without divulging too much info about it) is as follows - . Login (Enter Username, pass on the app) . Primary screen where the data is loaded from a webservice and presented . And post data back after a few updates by the user I'm using POST to send the data to the Webservice via HTTPS. I'm sanitizing the inputs, checking for length of the inputs, but that's the limit of my knowledge as far as security goes. Any other tips are greatly appreciated! Edit: I should probably add that our service needs to be subscribed to separately and the iPhone component of it cannot be used alone. So the average user will not have login credentials. And the app itself has healthcare data in it, so I'd rather not have anyone trying attacks from my login page. Thanks, Teja.

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• Help with MySQL Join Statement

  - by JasonS

  Hi, I just built a website and have realised that I need to have a top 3 highest rated albums.. I haven't built in something that keeps track of the ratings. Ratings are stored separately. Can someone show me how to put these together please. SELECT id, name FROM albums LIMIT 3 SELECT rating FROM ratings WHERE url=CONCAT('albums/show/', album.id) Let me just flesh it out a bit. I need to get back the following: From the albums table. id, name. From the ratings table I need to get back the average rating. ROUND((rating+rating+rating) / total ratings) The ratings. Users can rate everything on my website so I have a generic ratings table. The rating is stored with the url of the page it applies to. Hence, to get album ratings I need to have 'albums/show/{album_id}'. In hind sight I should have had a type and id field but it is a bit late now with a lunch iminient. Any help is much appreciated.

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• Search implementation dilemma: full text vs. plain SQL

  - by Ethan

  I have a MySQL/Rails app that needs search. Here's some info about the data: Users search within their own data only, so searches are narrowed down by user_id to begin with. Each user will have up to about five thousand records (they accumulate over time). I wrote out a typical user's records to a text file. The file size is 2.9 MB. Search has to cover two columns: title and body. title is a varchar(255) column. body is column type text. This will be lightly used. If I average a few searches per second that would be surprising. It's running an a 500 MB CentOS 5 VPS machine. I don't want relevance ranking or any kind of fuzziness. Searches should be for exact strings and reliably return all records containing the string. Simple date order -- newest to oldest. I'm using the InnoDB table type. I'm looking at plain SQL search (through the searchlogic gem) or full text search using Sphinx and the Thinking Sphinx gem. Sphinx is very fast and Thinking Sphinx is cool, but it adds complexity, a daemon to maintain, cron jobs to maintain the index. Can I get away with plain SQL search for a small scale app?

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• Discover periodic patterns in a large data-set

  - by Miner

  I have a large sequence of tuples on disk in the form (t1, k1) (t2, k2) ... (tn, kn) ti is a monotonically increasing timestamp and ki is a key (assume a fixed length string if needed). Neither ti nor ki are guaranteed to be unique. However, the number of unique tis and kis is huge (millions). n itself is very large (100 Million+) and the size of k (approx 500 bytes) makes it impossible to store everything in memory. I would like to find out periodic occurrences of keys in this sequence. For example, if I have the sequence (1, a) (2, b) (3, c) (4, b) (5, a) (6, b) (7, d) (8, b) (9, a) (10, b) The algorithm should emit (a, 4) and (b, 2). That is a occurs with a period of 4 and b occurs with a period of 2. If I build a hash of all keys and store the average of the difference between consecutive timestamps of each key and a std deviation of the same, I might be able to make a pass, and report only the ones that have an acceptable std deviation(ideally, 0). However, it requires one bucket per unique key, whereas in practice, I might have very few really periodic patterns. Any better ways?

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• Using outer query result in a subquery in postgresql

  - by brad

  I have two tables points and contacts and I'm trying to get the average points.score per contact grouped on a monthly basis. Note that points and contacts aren't related, I just want the sum of points created in a month divided by the number of contacts that existed in that month. So, I need to sum points grouped by the created_at month, and I need to take the count of contacts FOR THAT MONTH ONLY. It's that last part that's tricking me up. I'm not sure how I can use a column from an outer query in the subquery. I tried something like this: SELECT SUM(score) AS points_sum, EXTRACT(month FROM created_at) AS month, date_trunc('MONTH', created_at) + INTERVAL '1 month' AS next_month, (SELECT COUNT(id) FROM contacts WHERE contacts.created_at <= next_month) as contact_count FROM points GROUP BY month, next_month ORDER BY month So, I'm extracting the actual month that my points are being summed, and at the same time, getting the beginning of the next_month so that I can say "Get me the count of contacts where their created at is < next_month" But it complains that column next_month doesn't exist This is understandable as the subquery knows nothing about the outer query. Qualifying with points.next_month doesn't work either. So can someone point me in the right direction of how to achieve this? Tables: Points score | created_at 10 | "2011-11-15 21:44:00.363423" 11 | "2011-10-15 21:44:00.69667" 12 | "2011-09-15 21:44:00.773289" 13 | "2011-08-15 21:44:00.848838" 14 | "2011-07-15 21:44:00.924152" Contacts id | created_at 6 | "2011-07-15 21:43:17.534777" 5 | "2011-08-15 21:43:17.520828" 4 | "2011-09-15 21:43:17.506452" 3 | "2011-10-15 21:43:17.491848" 1 | "2011-11-15 21:42:54.759225" sum, month and next_month (without the subselect) sum | month | next_month 14 | 7 | "2011-08-01 00:00:00" 13 | 8 | "2011-09-01 00:00:00" 12 | 9 | "2011-10-01 00:00:00" 11 | 10 | "2011-11-01 00:00:00" 10 | 11 | "2011-12-01 00:00:00"

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• Maintaining a pool of DAO Class instances vs doing new operator

  - by Fazal

  we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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• Django aggregate query generating SQL error

  - by meepmeep

  I'm using Django 1.1.1 on a SQL Server 2005 db using the latest sqlserver_ado library. models.py includes: class Project(models.Model): name = models.CharField(max_length=50) class Thing(models.Model): project = models.ForeignKey(Project) reference = models.CharField(max_length=50) class ThingMonth(models.Model): thing = models.ForeignKey(Thing) timestamp = models.DateTimeField() ThingMonthValue = models.FloatField() class Meta: db_table = u'ThingMonthSummary' In a view, I have retrieved a queryset called 'things' which contains 25 Things: things = Thing.objects.select_related().filter(project=1).order_by('reference') I then want to do an aggregate query to get the average ThingMonthValue for the first 20 of those Things for a certain period, and the same value for the last 5. For the first 20 I do: averageThingMonthValue = ThingMonth.objects.filter(turbine__in=things[:20],timestamp__range="2009-01-01 00:00","2010-03-00:00")).aggregate(Avg('ThingMonthValue'))['ThingMonthValue__avg'] This works fine, and returns the desired value. For the last 5 I do: averageThingMonthValue = ThingMonth.objects.filter(turbine__in=things[20:],timestamp__range="2009-01-01 00:00","2010-03-00:00")).aggregate(Avg('ThingMonthValue'))['ThingMonthValue__avg'] But for this I get an SQL error: 'Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.' The SQL query being used by django reads: SELECT AVG([ThingMonthSummary].[ThingMonthValue]) AS [ThingMonthValue__avg] FROM [ThingMonthSummary] WHERE ([ThingMonthSummary].[thing_id] IN (SELECT _row_num, [id] FROM ( SELECT ROW_NUMBER() OVER ( ORDER BY [AAAA].[id] ASC) as _row_num, [AAAA].[id] FROM ( SELECT U0.[id] FROM [Thing] U0 WHERE U0.[project_id] = 1 ) AS [AAAA]) as QQQ where 20 < _row_num) AND [ThingMonthSummary].[timestamp] BETWEEN '01/01/09 00:00:00' and '03/01/10 00:00:00') Any idea why it works for one slice of the Things and not the second? I've checked and the two slices do contain the desired Things correctly.

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• how can I speed up insertion of many rows to a table via ADO.NET?

  - by jcollum

  I have a table that has 5 columns: AcctId (int), Address1 (varchar), Address2 (varchar), Person1 (varchar), Person2 (varchar) . I'm generating random data to insert into this table via a C# console application. I've tried doing this random data insert via SQL-Server and decided it was not a good solution -- SQL is not good at random on an each-row basis. Generating the random data -- 975k rows of it -- takes a minimal amount of time. It's in a List of custom objects. I need to take this random data and update many rows in the database with the new random data. I tried updating the rows one at a time, very slow because of the repeated searching of the List object in code. So I think the best approach is to put all the randomized data into a table in the database, then update all the other tables that use this data. I.e. UPDATE t SET t.Address1=d.Address1 FROM Table1 t INNER JOIN RandomizedData d ON d.AcctId = t.Acct_ID. The database is very un-normalized so this Acct data is sprinkled all over the place. I've got no control of the normalization. So, having decided to insert all of the randomized data into a single table, I set out to create insert scripts: USE TheDatabase Insert tmp_RandomizedData SELECT 1,'4392 EIGHTH AVE','','JENNIFER CARTER','BARBARA CARTER' UNION ALL SELECT 2,'2168 MAIN ST','HNGR F','DANIEL HERNANDEZ','SUSAN MARTIN' // etc another 98 times... // FYI, this is not real data! I'm building this INSERT script in batches of 100. It's taking on average 175 ms to run each insert. Does this seem like a long time? It's going to take about 35 mins to run the whole insert. The table doesn't have a primary key or any indexes. I was planning on adding those after all the data in inserted (thinking that that would be faster). Is there a better way to do this?

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• Speeding up a soap powered website

  - by ChrisRamakers

  Hi all, We're currently looking into doing some performance tweaking on a website which relies heavily on a Soap webservice. But ... our servers are located in Belgium and the webservice we connect to is locate in San Francisco so it's a long distance connection to say the least. Our website is PHP powered, using PHP's built in SoapClient class. On average a call to the webservice takes 0.7 seconds and we are doing about 3-5 requests per page. All possible request/response caching is already implemented so we are now looking at other ways to improved the connection speed. This is the code which instantiates the SoapClient, what i'm looking for now is other ways/methods to improve speed on single requestes. Anyone has idea's or suggestions? private function _createClient() { try { $wsdl = sprintf($this->config->wsUrl.'?wsdl', $this->wsdl); $client = new SoapClient($wsdl, array( 'soap_version' => SOAP_1_1, 'encoding' => 'utf-8', 'connection_timeout' => 5, 'cache_wsdl' => 1, 'trace' => 1, 'features' => SOAP_SINGLE_ELEMENT_ARRAYS )); $header_tags = array('username' => new SOAPVar($this->config->wsUsername, XSD_STRING, null, null, null, $this->ns), 'password' => new SOAPVar(md5($this->config->wsPassword), XSD_STRING, null, null, null, $this->ns)); $header_body = new SOAPVar($header_tags, SOAP_ENC_OBJECT); $header = new SOAPHeader($this->ns, 'AuthHeaderElement', $header_body); $client->__setSoapHeaders($header); } catch (SoapFault $e){ controller('Error')->error($id.': Webservice connection error '.$e->getCode()); exit; } $this->client = $client; return $this->client; }

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• R: How to remove outliers from a smoother in ggplot2?

  - by John

  I have the following data set that I am trying to plot with ggplot2, it is a time series of three experiments A1, B1 and C1 and each experiment had three replicates. I am trying to add a stat which detects and removes outliers before returning a smoother (mean and variance?). I have written my own outlier function (not shown) but I expect there is already a function to do this, I just have not found it. I've looked at stat_sum_df("median_hilow", geom = "smooth") from some examples in the ggplot2 book, but I didn't understand the help doc from Hmisc to see if it removes outliers or not. Is there a function to remove outliers like this in ggplot, or where would I amend my code below to add my own function? library (ggplot2) data = data.frame (day = c(1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7), od = c( 0.1,1.0,0.5,0.7 ,0.13,0.33,0.54,0.76 ,0.1,0.35,0.54,0.73 ,1.3,1.5,1.75,1.7 ,1.3,1.3,1.0,1.6 ,1.7,1.6,1.75,1.7 ,2.1,2.3,2.5,2.7 ,2.5,2.6,2.6,2.8 ,2.3,2.5,2.8,3.8), series_id = c( "A1", "A1", "A1","A1", "A1", "A1", "A1","A1", "A1", "A1", "A1","A1", "B1", "B1","B1", "B1", "B1", "B1","B1", "B1", "B1", "B1","B1", "B1", "C1","C1", "C1", "C1", "C1","C1", "C1", "C1", "C1","C1", "C1", "C1"), replicate = c( "A1.1","A1.1","A1.1","A1.1", "A1.2","A1.2","A1.2","A1.2", "A1.3","A1.3","A1.3","A1.3", "B1.1","B1.1","B1.1","B1.1", "B1.2","B1.2","B1.2","B1.2", "B1.3","B1.3","B1.3","B1.3", "C1.1","C1.1","C1.1","C1.1", "C1.2","C1.2","C1.2","C1.2", "C1.3","C1.3","C1.3","C1.3")) > data day od series_id replicate 1 1 0.10 A1 A1.1 2 3 1.00 A1 A1.1 3 5 0.50 A1 A1.1 4 7 0.70 A1 A1.1 5 1 0.13 A1 A1.2 6 3 0.33 A1 A1.2 7 5 0.54 A1 A1.2 8 7 0.76 A1 A1.2 9 1 0.10 A1 A1.3 10 3 0.35 A1 A1.3 11 5 0.54 A1 A1.3 12 7 0.73 A1 A1.3 13 1 1.30 B1 B1.1 This is what I have so far and is working nicely, but outliers are not removed: r <- ggplot(data = data, aes(x = day, y = od)) r + geom_point(aes(group = replicate, color = series_id)) + # add points geom_line(aes(group = replicate, color = series_id)) + # add lines geom_smooth(aes(group = series_id)) # add smoother, average of each replicate

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