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• Spotlight on an office - Denmark

  - by jessica.ebbelaar(at)oracle.com

  Hi, my name is Michael. I work as an Intern at the Danish office in Ballerup. My job is a part-time position beside my bachelor study in International Business at Copenhagen Business School. I joined Oracle end of February last year, and what a thrilling ride it has been! Last year, when I was offered the position, there was no doubt that I wanted to go for it. Back then, I only had little idea about Oracle as a company and what kind of exciting assignments lay ahead of me. My main role is internal communications, i.e. editor of a monthly employee’s news letter; Newszone. It is an interesting task, since it requires that I am updated on the different activities that take place within the Oracle Denmark office. I try to bring interesting articles, which are relevant and interesting news to my colleagues and it allows me to interact with many different persons at the office and to learn from their experience, which give me great inspiration and ideas for the magazine. Besides being the editor of Newszone, I also make sure that other communication flow freely at the Oracle Denmark office. I do this through our LCD screen channels. I update the internal channel with the latest information and important messages for employees, and on the external channel I circulate marketing videos featuring Oracle products and customer reference stories. In addition to this, I have the responsibility acting as a content manager of the Local Communication Denmark site on MyOracle (UCM). These are more or less my usual work assignments. On top of these I take care of various ad hoc assignments such as updating the GCM database, renew newspaper subscriptions etc. The Oracle Denmark office Being part of the local employees club I also assist with arranging social events outside working hours – e.g. evenings at the theater or cinema or by attending many of the sportsactivities;such as our running club, cycling club, food club and book club. These activities have indeed helped me grow my personal network within Oracle.  The office is packed with engaging, high-paced and motivated people who manage to take time off to spend a day attending Corporate Social Responsibility initiatives, one of them being GVD (Global Volunteer Day) with approximately 40 employees attending. This proofs some of the social responsible aspects of Oracle. I was positively surprised on how the office (named O-Zone) is designed. The office is designed into three distinct zones, namely Call zone, Project and Dialogue zone and Quiet zone, having different working environments for different job roles. The other thing which I like is that you do not have your own desk, which means you get to sit next to different people every day, getting new ideas and inspiration as well as getting to know more people in the organization you work in. To sum up: If you are considering pursuing an intern or a career after graduation in Oracle, do it! You will not regret it. It has given me many relevant practical experiences beside my study, and I am sure many great experiences will await you too.   Want to know more about the current vacancies in Denmark? Check http://campus.oracle.com for all of our vacancies.

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• Join our Marketing Intelligence Team in Dublin!

  - by jessica.ebbelaar

  Do you want to work with the brightest minds in the industry? Want to be part of a global team that’s changing the way the world does business? Then Oracle is the place for YOU. Join now as a Marketing Intelligence Representative. You will have the opportunity to develop within the role through working alongside the Business Development, Sales and Marketing teams within Oracle. The Marketing Intelligence Group is viewed as a true talent pool for the Business Development and Sales Teams. Oracle offers a structured training programme for Marketing Intelligence Representatives and Business Development Consultants including our approved sales certified training methodology along with regular product training. Miriam started her career as a Marketing Intelligence Representative six years ago, and shares what she has learned and how her career is progressing. My Career Path at Oracle: June 2005 – October 2005: Profiler in the Marketing Intelligence Team November 2005 - October 2006: Team Leader for MIT November 2006 - February 2008: Business Development Consultant Iberia March 2008 - December 2010: Lead Management Specialist Currently: Sales Program Manager for Iberia & Benelux What did you learn from your role in the Market Intelligence Team Being a Profiler helped me to understand how an organisation works, from the beginning to the end. It is like being in University but being paid! The three key things I learnt in this role are: Knowledge of customers: You are on the phone with over 70 customers daily. Not only does this give you an overview of the IT infrastructure of the customers companies but also how to manage their questions and rejections. Essentially you are learning how to convert their pain and complaints into business opportunities. Knowledge of Oracle: As a Profiler you get an excellent overview of how Oracle works internally, from Marketing to Sales, without forgetting the Operations Team. Knowledge about yourself: As a Profiler I learnt how to work outside of my comfort zone, there is a new challenge almost every day but Oracle are there to support you every step of the way. Oracle really invests in developing the MIT Team and as a Profiler you can expect product and sales training on a monthly basis. How did you progress from MIT to Business Development Group (BDG)? I made sure that my manager knew from the very beginning that I was keen to progress at Oracle and I was set very clear objectives to help me reach my goal.  My manager was very supportive and ensured I received all the training I needed. After I became a Team Leader of Profiling, I moved to an Iberia BDG position. How you feel your experience in MI has helped you in your current role? I truly believe that the MI position gives you a great overview of Oracle and this has really helped me in my current position.  I am the Sales Program Manager for IBERIA & Benelux and in my campaigns I need to target the right companies and the right job specs.  My time in the Market Intelligence team really helped me to understand how to focus and target my campaigns so I know I don’t miss any business opportunities! How would you sum up your Oracle experience? Oracle is a big organisation with big opportunities. With the right skills and with the great training programs that Oracle offer, the only limit is you! If you have any questions related to this article feel free to contact [email protected] You can find all our job opportunities via http://campus.oracle.com. Tags van Technorati: Marketing Intelligence,Benelux,Iberia,Profiler,Business Development,Sales Representatives,BDG,Business Development Group,opportunities,Oracle

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• Deploying an SSL Application to Windows Azure &ndash; The Dark Secret

  - by ToStringTheory

  When working on an application that had been in production for some time, but was about to have a shopping cart added to it, the necessity for SSL certificates came up.  When ordering the certificates through the vendor, the certificate signing request (CSR) was generated through the providers (http://register.com) web interface, and within a day, we had our certificate. At first, I thought that the certification process would be the hard part…  Little did I know that my fun was just beginning… The Problem I’ll be honest, I had never really secured a site before with SSL.  This was a learning experience for me in the first place, but little did I know that I would be learning more than the simple procedure.  I understood a bit about SSL already, the mechanisms in how it works – the secure handshake, CA’s, chains, etc…  What I didn’t realize was the importance of the CSR in the whole process.  Apparently, when the CSR is created, a public key is created at the same time, as well as a private key that is stored locally on the PC that generated the request.  When the certificate comes back and you import it back into IIS (assuming you used IIS to generate the CSR), all of the information is combined together and the SSL certificate is added into your store. Since at the time the certificate had been ordered for our site, the selection to use the online interface to generate the CSR was chosen, the certificate came back to us in 5 separate files: A root certificate – (*.crt file) An intermediate certifcate – (*.crt file) Another intermediate certificate – (*.crt file) The SSL certificate for our site – (*.crt file) The private key for our certificate – (*.key file) Well, in case you don’t know much about Windows Azure and SSL certificates, the first thing you should learn is that certificates can only be uploaded to Azure if they are in a PFX package – securable by a password.  Also, in the case of our SSL certificate, you need to include the Private Key with the file.  As you can see, we didn’t have a PFX file to upload. If you don’t get the simple PFX from your hosting provider, but rather the multiple files, you will soon find out that the process has turned from something that should be simple – to one that borders on a circle of hell… Probably between the fifth and seventh somewhere… The Solution The solution is to take the files that make up the certificates chain and key, and combine them into a file that can be imported into your local computers store, as well as uploaded to Windows Azure.  I can not take the credit for this information, as I simply researched a while before finding out how to do this. Download the OpenSSL for Windows toolkit (Win32 OpenSSL v1.0.1c) Install the OpenSSL for Windows toolkit Download and move all of your certificate files to an easily accessible location (you'll be pointing to them in the command prompt, so I put them in a subdirectory of the OpenSSL installation) Open a command prompt Navigate to the folder where you installed OpenSSL Run the following command: openssl pkcs12 -export –out {outcert.pfx} –inkey {keyfile.key}      –in {sslcert.crt} –certfile {ca1.crt} –certfile (ca2.crt) From this command, you will get a file, outcert.pfx, with the sum total of your ssl certificate (sslcert.crt), private key {keyfile.key}, and as many CA/chain files as you need {ca1.crt, ca2.crt}. Taking this file, you can then import it into your own IIS in one operation, instead of importing each certificate individually.  You can also upload the PFX to Azure, and once you add the SSL certificate links to the cloud project in Visual Studio, your good to go! Conclusion When I first looked around for a solution to this problem, there were not many places online that had the information that I was looking for.  While what I ended up having to do may seem obvious, it isn’t for everyone, and I hope that this can at least help one developer out there solve the problem without hours of work!

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• Script to UPDATE STATISTICS with time window

  - by Bill Graziano

  I recently spent some time troubleshooting odd query plans and came to the conclusion that we needed better statistics.  We’ve been running sp_updatestats but apparently it wasn’t sampling enough of the table to get us what we needed.  I have a pretty limited window at night where I can hammer the disks while this runs.  The script below just calls UPDATE STATITICS on all tables that “need” updating.  It defines need as any table whose statistics are older than the number of days you specify (30 by default).  It also has a throttle so it breaks out of the loop after a set amount of time (60 minutes).  That means it won’t start processing a new table after this time but it might take longer than this to finish what it’s doing.  It always processes the oldest statistics first so it will eventually get to all of them.  It defaults to sample 25% of the table.  I’m not sure that’s a good default but it works for now.  I’ve tested this in SQL Server 2005 and SQL Server 2008.  I liked the way Michelle parameterized her re-index script and I took the same approach. CREATE PROCEDURE dbo.UpdateStatistics ( @timeLimit smallint = 60 ,@debug bit = 0 ,@executeSQL bit = 1 ,@samplePercent tinyint = 25 ,@printSQL bit = 1 ,@minDays tinyint = 30 )AS/******************************************************************* Copyright Bill Graziano 2010*******************************************************************/SET NOCOUNT ON;PRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + 'Launching...'IF OBJECT_ID('tempdb..#status') IS NOT NULL DROP TABLE #status;CREATE TABLE #status( databaseID INT , databaseName NVARCHAR(128) , objectID INT , page_count INT , schemaName NVARCHAR(128) Null , objectName NVARCHAR(128) Null , lastUpdateDate DATETIME , scanDate DATETIME CONSTRAINT PK_status_tmp PRIMARY KEY CLUSTERED(databaseID, objectID));DECLARE @SQL NVARCHAR(MAX);DECLARE @dbName nvarchar(128);DECLARE @databaseID INT;DECLARE @objectID INT;DECLARE @schemaName NVARCHAR(128);DECLARE @objectName NVARCHAR(128);DECLARE @lastUpdateDate DATETIME;DECLARE @startTime DATETIME;SELECT @startTime = GETDATE();DECLARE cDB CURSORREAD_ONLYFOR select [name] from master.sys.databases where database_id > 4OPEN cDBFETCH NEXT FROM cDB INTO @dbNameWHILE (@@fetch_status <> -1)BEGIN IF (@@fetch_status <> -2) BEGIN SELECT @SQL = ' use ' + QUOTENAME(@dbName) + ' select DB_ID() as databaseID , DB_NAME() as databaseName ,t.object_id ,sum(used_page_count) as page_count ,s.[name] as schemaName ,t.[name] AS objectName , COALESCE(d.stats_date, ''1900-01-01'') , GETDATE() as scanDate from sys.dm_db_partition_stats ps join sys.tables t on t.object_id = ps.object_id join sys.schemas s on s.schema_id = t.schema_id join ( SELECT object_id, MIN(stats_date) as stats_date FROM ( select object_id, stats_date(object_id, stats_id) as stats_date from sys.stats) as d GROUP BY object_id ) as d ON d.object_id = t.object_id where ps.row_count > 0 group by s.[name], t.[name], t.object_id, COALESCE(d.stats_date, ''1900-01-01'') ' SET ANSI_WARNINGS OFF; Insert #status EXEC ( @SQL); SET ANSI_WARNINGS ON; END FETCH NEXT FROM cDB INTO @dbNameENDCLOSE cDBDEALLOCATE cDBDECLARE cStats CURSORREAD_ONLYFOR SELECT databaseID , databaseName , objectID , schemaName , objectName , lastUpdateDate FROM #status WHERE DATEDIFF(dd, lastUpdateDate, GETDATE()) >= @minDays ORDER BY lastUpdateDate ASC, page_count desc, [objectName] ASC OPEN cStatsFETCH NEXT FROM cStats INTO @databaseID, @dbName, @objectID, @schemaName, @objectName, @lastUpdateDateWHILE (@@fetch_status <> -1)BEGIN IF (@@fetch_status <> -2) BEGIN IF DATEDIFF(mi, @startTime, GETDATE()) > @timeLimit BEGIN PRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + '*** Time Limit Reached ***'; GOTO __DONE; END SELECT @SQL = 'UPDATE STATISTICS ' + QUOTENAME(@dBName) + '.' + QUOTENAME(@schemaName) + '.' + QUOTENAME(@ObjectName) + ' WITH SAMPLE ' + CAST(@samplePercent AS NVARCHAR(100)) + ' PERCENT;'; IF @printSQL = 1 PRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + @SQL + ' (Last Updated: ' + CAST(@lastUpdateDate AS VARCHAR(100)) + ')' IF @executeSQL = 1 BEGIN EXEC (@SQL); END END FETCH NEXT FROM cStats INTO @databaseID, @dbName, @objectID, @schemaName, @objectName, @lastUpdateDateEND__DONE:CLOSE cStatsDEALLOCATE cStatsPRINT '[ ' + CAST(GETDATE() AS VARCHAR(100)) + ' ] ' + 'Completed.'GO

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• To SYNC or not to SYNC – Part 4

  - by AshishRay

  This is Part 4 of a multi-part blog article where we are discussing various aspects of setting up Data Guard synchronous redo transport (SYNC). In Part 1 of this article, I debunked the myth that Data Guard SYNC is similar to a two-phase commit operation. In Part 2, I discussed the various ways that network latency may or may not impact a Data Guard SYNC configuration. In Part 3, I talked in details regarding why Data Guard SYNC is a good thing, and the distance implications you have to keep in mind. In this final article of the series, I will talk about how you can nicely complement Data Guard SYNC with the ability to failover in seconds. Wait - Did I Say “Seconds”? Did I just say that some customers do Data Guard failover in seconds? Yes, Virginia, there is a Santa Claus. Data Guard has an automatic failover capability, aptly called Fast-Start Failover. Initially available with Oracle Database 10g Release 2 for Data Guard SYNC transport mode (and enhanced in Oracle Database 11g to support Data Guard ASYNC transport mode), this capability, managed by Data Guard Broker, lets your Data Guard configuration automatically failover to a designated standby database. Yes, this means no human intervention is required to do the failover. This process is controlled by a low footprint Data Guard Broker client called Observer, which makes sure that the primary database and the designated standby database are behaving like good kids. If something bad were to happen to the primary database, the Observer, after a configurable threshold period, tells that standby, “Your time has come, you are the chosen one!” The standby dutifully follows the Observer directives by assuming the role of the new primary database. The DBA or the Sys Admin doesn’t need to be involved. And - in case you are following this discussion very closely, and are wondering … “Hmmm … what if the old primary is not really dead, but just network isolated from the Observer or the standby - won’t this lead to a split-brain situation?” The answer is No - It Doesn’t. With respect to why-it-doesn’t, I am sure there are some smart DBAs in the audience who can explain the technical reasons. Otherwise - that will be the material for a future blog post. So - this combination of SYNC and Fast-Start Failover is the nirvana of lights-out, integrated HA and DR, as practiced by some of our advanced customers. They have observed failover times (with no data loss) ranging from single-digit seconds to tens of seconds. With this, they support operations in industry verticals such as manufacturing, retail, telecom, Internet, etc. that have the most demanding availability requirements. One of our leading customers with massive cloud deployment initiatives tells us that they know about server failures only after Data Guard has automatically completed the failover process and the app is back up and running! Needless to mention, Data Guard Broker has the integration hooks for interfaces such as JDBC and OCI, or even for custom apps, to ensure the application gets automatically rerouted to the new primary database after the database level failover completes. Net Net? To sum up this multi-part blog article, Data Guard with SYNC redo transport mode, plus Fast-Start Failover, gives you the ideal triple-combo - that is, it gives you the assurance that for critical outages, you can failover your Oracle databases: very fast without human intervention, and without losing any data. In short, it takes the element of risk out of critical IT operations. It does require you to be more careful with your network and systems planning, but as far as HA is concerned, the benefits outweigh the investment costs. So, this is what we in the MAA Development Team believe in. What do you think? How has your deployment experience been? We look forward to hearing from you!

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 6

  - by MarkPearl

  Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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• what differs a computer scientist/software engineer to regular people who learn programming language and APIs?

  - by Amumu

  In University, we learn and reinvent the wheel a lot to truly learn the programming concepts. For example, we may learn assembly language to understand, what happens inside the box, and how the system operates, when we execute our code. This helps understanding higher level concepts deeper. For example, memory management like in C is just an abstraction of manually managed memory contents and addresses. The problem is, when we're going to work, usually productivity is required more. I could program my own containers, or string class, or date/time (using POSIX with C system call) to do the job, but then, it would take much longer time to use existing STL or Boost library, which abstract all of those thing and very easy to use. This leads to an issue, that a regular person doesn't need to get through all the low level/under the hood stuffs, who learns only one programming language and using language-related APIs. These people may eventually compete with the mainstream graduates from computer science or software engineer and call themselves programmers. At first, I don't think it's valid to call them programmers. I used to think, a real programmer needs to understand the computer deeply (but not at the electronic level). But then I changed my mind. After all, they get the job done and satisfy all the test criteria (logic, performance, security...), and in business environment, who cares if you're an expert and understand how computer works or not. You may get behind the "amateurs" if you spend to much time learning about how things work inside. It is totally valid for those people to call themselves programmers. This makes me confuse. So, after all, programming should be considered an universal skill? Does programming language and concepts matter or the problems we solve matter? For example, many C/C++ vs Java and other high level language, one of the main reason is because C/C++ features performance, as well as accessing low level facility. One of the main reason (in my opinion), is coding in C/C++ seems complex, so people feel good about it (not trolling anyone, just my observation, and my experience as well. Try to google "C hacker syndrome"). While Java on the other hand, made for simplifying programming tasks to help developers concentrate on solving their problems. Based on Java rationale, if the programing language keeps evolve, one day everyone can map their logic directly with natural language. Everyone can program. On that day, maybe real programmers are mathematicians, who could perform most complex logic (including business logic and academic logic) without worrying about installing/configuring compiler, IDEs? What's our job as a computer scientist/software engineer? To solve computer specific problems or to solve problems in general? For example, take a look at this exame: http://cm.baylor.edu/ICPCWiki/attach/Problem%20Resources/2010WorldFinalProblemSet.pdf . The example requires only basic knowledge about the programming language, but focus more on problem solving with the language. In sum, what differs a computer scientist/software engineer to regular people who learn programming language and APIs? A mathematician can be considered a programmer, if he is good enough to use programming language to implement his formula. Can we programmer do this? Probably not for most of us, since we specialize about computer, not math. An electronic engineer, who learns how to use C to program for his devices, can be considered a programmer. If the programming languages keep being simplified, may one day the software engineers, who implements business logic and create softwares, be obsolete? (Not for computer scientist though, since many of the CS topics are scientific, and science won't change, but technology will).

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• A proposal for #DAX Code Formatting #ssas #powerpivot #tabular

  - by Marco Russo (SQLBI)

  I recently published a set of rules for DAX code formatting. The following is an example of what I obtain: CALCULATE (     SUMX (         Orders,         Orders[Amount]     ),     FILTER (         ALL ( Customers ),         CALCULATE (             COUNTROWS ( Sales ),             ALL ( Calendar[Date] )         ) > 42 + 8 – 25 * ( 3 - 1 )             + 2 – 1 + 2 – 1             + CALCULATE (                   2 + 2 – 2                   + 2 - 2               )             – CALCULATE ( 4 )     ) ) The goal is to improve code readability and I look forward to implement a code formatting feature in DAX Studio. The DAX Editor already supports the rules described in the article. I am also considering whether to add a rule specific for ADDCOLUMNS / SUMMARIZE because I would like to see the “pairs” of arguments to define a column in the same row or with a special indentation rule (DAX expression for a column is indented in the line following the column name). EVALUATE CALCULATETABLE (        CALCULATETABLE (         SUMMARIZE (             Audience,             'Date'[Year],             Individuals[Gender],             Individuals[AgeRange],             "Num of Rows", FORMAT (COUNTROWS (Audience), "#,#"),             "Weighted Mean Age",                 SUMX (Audience, Audience[Weight] * Audience[Age]) / SUM (Audience[Weight])         ),         SUMMARIZE (             BridgeIndividualsTargets,             Individuals[ID_Individual]         ),         Audience[Weight] > 0        ),        Targets[Target] = "Maschi",     'Date'[Year] = 2010,     'Date'[MonthName] = "January" ) I would like to get feedback for that – you can use comments here or comments in original article. Thanks!

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• Scenarios for Throwing Exceptions

  - by Joe Mayo

  I recently came across a situation where someone had an opinion that differed from mine of when an exception should be thrown. This particular case was an issue opened on LINQ to Twitter for an Exception on EndSession.  The premise of the issue was that the poster didn’t feel an exception should be raised, regardless of authentication status.  As first, this sounded like a valid point.  However, I went back to review my code and decided not to make any changes. Here's my rationale: 1. The exception doesn’t occur if the user is authenticated when EndAccountSession is called. 2. The exception does occur if the user is not authenticated when EndAccountSession is called. 3. The exception represents the fact that EndAccountSession is not able to fulfill its intended purpose - to end the session.  If a session never existed, then it would not be possible to perform the requested action.  Therefore, an exception is appropriate. To help illustrate how to handle this situation, I've modified the following code in Program.cs in the LinqToTwitterDemo project to illustrate the situation: static void EndSession(ITwitterAuthorizer auth) { using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/")) { try { //Log twitterCtx.Log = Console.Out; var status = twitterCtx.EndAccountSession(); Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } catch (TwitterQueryException tqe) { var webEx = tqe.InnerException as WebException; if (webEx != null) { var webResp = webEx.Response as HttpWebResponse; if (webResp != null && webResp.StatusCode == HttpStatusCode.Unauthorized) Console.WriteLine("Twitter didn't recognize you as having been logged in. Therefore, your request to end session is illogical.\n"); } var status = tqe.Response; Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } } } As expected, LINQ to Twitter wraps the exception in a TwitterQueryException as the InnerException.  The TwitterQueryException serves a very useful purpose through it's Response property.  Notice in the example above that the response has Request and Error proprieties.  These properties correspond to the information that Twitter returns as part of it's response payload.  This is often useful while debugging to help you understand why Twitter was unable to perform the  requested action.  Other times, it's cryptic, but that's another story.  At least you have some way of knowing in your code how to anticipate and handle these situations, along with having extra information to debug with. To sum things up, there are two points to make: when and why an exception should be raised and when to wrap and re-throw an exception in a custom exception type. I felt it was necessary to allow the exception to be raised because the called method was unable to perform the task it was designed for.  I also felt that it is inappropriate for a general library to do anything with exceptions because that could potentially hide a problem from the caller.  A related point is that it should be the exclusive decision of the application that uses the library on what to do with an exception.  Another aspect of this situation is that I wrapped the exception in a custom exception and re-threw.  This is a tough call because I don’t want to hide any stack trace information.  However, the need to make the exception more meaningful by including vital information returned from Twitter swayed me in the direction to design an interface that was as helpful as possible to library consumers.  As shown in the code above, you can dig into the exception and pull out a lot of good information, such as the fact that the underlying HTTP response was a 401 Unauthorized.  In all, trade-offs are seldom perfect for all cases, but combining the fact that the method was unable to perform its intended function, this is a library, and the extra information can be more helpful, it seemed to be the better design. @JoeMayo

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• Blink-Data vs Instinct?

  - by Samantha.Y. Ma

  In his landmark bestseller Blink, well-known author and journalist Malcolm Gladwell explores how human beings everyday make seemingly instantaneous choices --in the blink of an eye--and how we “think without thinking.”  These situations actually aren’t as simple as they seem, he postulates; and throughout the book, Gladwell seeks answers to questions such as: 1.    What makes some people good at thinking on their feet and making quick spontaneous decisions?2.    Why do some people follow their instincts and win, while others consistently seem to stumble into error?3.    Why are some of the best decisions often those that are difficult to explain to others?In Blink, Gladwell introduces us to the psychologist who has learned to predict whether a marriage will last, based on a few minutes of observing a couple; the tennis coach who knows when a player will double-fault before the racket even makes contact with the ball; the antiquities experts who recognize a fake at a glance. Ultimately, Blink reveals that great decision makers aren't those who spend the most time deliberating or analyzing information, but those who focus on key factors among an overwhelming number of variables-- i.e., those who have perfected the art of "thin-slicing.” In Data vs. Instinct: Perfecting Global Sales Performance, a new report sponsored by Oracle, the Economist Intelligence Unit (EIU) explores the roles data and instinct play in decision-making by sales managers and discusses how sales executives can increase sales performance through more effective  territory planning and incentive/compensation strategies.If you are a sales executive, ask yourself this:  “Do you rely on knowledge (data) when you plan out your sales strategy?  If you rely on data, how do you ensure that your data sources are reliable, up-to-date, and complete?  With the emergence of social media and the proliferation of both structured and unstructured data, how do you know that you are applying your information/data correctly and in-context?  Three key findings in the report are:•    Six out of ten executives say they rely more on data than instinct to drive decisions. •    Nearly one half (48 percent) of incentive compensation plans do not achieve the desired results. •    Senior sales executives rely more on current and historical data than on forecast data. Strikingly similar to what Gladwell concludes in Blink, the report’s authors succinctly sum up their findings: "The best outcome is a combination of timely information, insightful predictions, and support data."Applying this insight is crucial to creating a sound sales plan that drives alignment and results.  In the area of sales performance management, “territory programs and incentive compensation continue to present particularly complex challenges in an increasingly globalized market," say the report’s authors. "It behooves companies to get a better handle on translating that data into actionable and effective plans." To help solve this challenge, CRM Oracle Fusion integrates forecasting, quotas, compensation, and territories into a single system.   For example, Oracle Fusion CRM provides a natural integration between territories, which define the sales targets (e.g., collection of accounts) for the sales force, and quotas, which quantify the sales targets. In fact, territory hierarchy is a core analytic dimension to slice and dice sales results, using sales analytics and alerts to help you identify where problems are occurring. This makes territoriesStart tapping into both data and instinct effectively today with Oracle Fusion CRM.   Here is a short video to provide you with a snapshot of how it can help you optimize your sales performance.  

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• Getting the number of fragments which passed the depth test

  - by Etan

  In "modern" environments, the "NV Occlusion Query" extension provides a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension is not available. What is the most performant approach to implement a similar behaviour in the fragment shader? Some of my ideas: Render the object completely in white, then count all the colors together using a two-pass shader where first a vertical line is rendered and for each fragment the shader computes the sum over the whole row. Then, a single vertex is rendered whose fragment sums all the partial sums of the first pass. Doesn't seem to be very efficient. Render the object completely in white over a black background. Downsample recursively, abusing the hardware linear interpolation between textures until being at a reasonably small resolution. This leads to fragments which have a greyscale level depending on the number of white pixels where in their corresponding region. Is this even accurate enough? Use mipmaps and simply read the pixel on the 1x1 level. Again the question of accuracy and if it is even possible using non-power-of-two textures. The problem wit these approaches is, that the pipeline gets stalled which results in major performance issues. Therefore, I'm looking for a more performant way to accomplish my goal. Using the EXT_OCCLUSION_QUERY_BOOLEAN extension Apple introduced EXT_OCCLUSION_QUERY_BOOLEAN in iOS 5.0 for iPad 2. "4.1.6 Occlusion Queries Occlusion queries use query objects to track the number of fragments or samples that pass the depth test. An occlusion query can be started and finished by calling BeginQueryEXT and EndQueryEXT, respectively, with a target of ANY_SAMPLES_PASSED_EXT or ANY_SAMPLES_PASSED_CONSERVATIVE_EXT. When an occlusion query is started with the target ANY_SAMPLES_PASSED_EXT, the samples-boolean state maintained by the GL is set to FALSE. While that occlusion query is active, the samples-boolean state is set to TRUE if any fragment or sample passes the depth test. When the occlusion query finishes, the samples-boolean state of FALSE or TRUE is written to the corresponding query object as the query result value, and the query result for that object is marked as available. If the target of the query is ANY_SAMPLES_PASSED_CONSERVATIVE_EXT, an implementation may choose to use a less precise version of the test which can additionally set the samples-boolean state to TRUE in some other implementation dependent cases." The first sentence hints on a behavior which is exactly what I'm looking for: getting the number of pixels which passed the depth test in an asynchronous manner without much performance loss. However, the rest of the document describes only how to get boolean results. Is it possible to exploit this extension to get the pixel count? Does the hardware support it so that there may be hidden API to get access to the pixel count? Other extensions which could be exploitable would be debugging features like the number of times the fragment shader was invoked (PSInvocations in DirectX - not sure if something simila is available in OpenGL ES). However, this would also result in a pipeline stall.

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• Intern Screening - Software 'Quiz'

  - by Jeremy1026

  I am in charge of selecting a new software development intern for a company that I work with. I wanted to throw a little 'quiz' at the applicants before moving forth with interviews so as to weed out the group a little bit to find some people that can demonstrate some skill. I put together the following quiz to send to applicants, it focuses only on PHP, but that is because that is what about 95% of the work will be done in. I'm hoping to get some feedback on A. if its a good idea to send this to applicants and B. if it can be improved upon. # 1. FizzBuzz # Write a small application that does the following: # Counts from 1 to 100 # For multiples of 3 output "Fizz" # For multiples of 5 output "Buzz" # For multiples of 3 and 5 output "FizzBuzz" # For numbers that are not multiples of 3 nor 5 output the number. <?php ?> # 2. Arrays # Create a multi-dimensional array that contains # keys for 'id', 'lot', 'car_model', 'color', 'price'. # Insert three sets of data into the array. <?php ?> # 3. Comparisons # Without executing the code, tell if the expressions # below will return true or false. <?php if ((strpos("a","abcdefg")) == TRUE) echo "True"; else echo "False"; //True or False? if ((012 / 4) == 3) echo "True"; else echo "False"; //True or False? if (strcasecmp("abc","ABC") == 0) echo "True"; else echo "False"; //True or False? ?> # 4. Bug Checking # The code below is flawed. Fix it so that the code # runs properly without producing any Errors, Warnings # or Notices, and returns the proper value. <?php //Determine how many parts are needed to create a 3D pyramid. function find_3d_pyramid($rows) { //Loop through each row. for ($i = 0; $i < $rows; $i++) { $lastRow++; //Append the latest row to the running total. $total = $total + (pow($lastRow,3)); } //Return the total. return $total; } $i = 3; echo "A pyramid consisting of $i rows will have a total of ".find_3d_pyramid($i)." pieces."; ?> # 5. Quick Examples # Create a small example to complete the task # for each of the following problems. # Create an md5 hash of "Hello World"; # Replace all occurances of "_" with "-" in the string "Welcome_to_the_universe." # Get the current date and time, in the following format, YYYY/MM/DD HH:MM:SS AM/PM # Find the sum, average, and median of the following set of numbers. 1, 3, 5, 6, 7, 9, 10. # Randomly roll a six-sided die 5 times. Store the 5 rolls into an array. <?php ?>

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• Get More Value From Your Oracle Premier Support Investment

  - by Get Proactive Customer Adoption Team

  Untitled Document The Return on Investment in Support Training I’m a typical software user. I’ve been using spreadsheets almost daily for the past 10 years or so. I know how to enter simple formulas, format cells, import files, and I can sort and filter. Sometimes I even use a pivot table. I never attended training. I learnt everything I know on the fly. Sometimes it was intuitive and easy, other times I had to spend minutes and even hours searching for a solution. Yet when I see what some other people can do with their spreadsheets, I know I’m utilizing maybe 15% of the functionality. Pity, one day I really have to sign up for training. Why haven’t I done it yet? Ah, you know, I’m a busy person, I have work to do. And if I need to use a feature that I am unfamiliar with, I’ll spend time on it only when I really need it. Now wait. When I recall how much time I spent trying to figure how things work compared to time I spent doing the productive work, I realize it was not insignificant. I’m unable to sum up all the time I spent ‘learning’ on the fly, but I’m sure it’s been days or even weeks. And after all this time, I’ve mastered 15% of its features. If only I had attended training years ago. That investment would have paid back 10 times! Working with My Oracle Support is no different. Our customers typically use simple search, create service requests, and download patches. They think they know how to use My Oracle Support. And they’re right. They know something but often they’re utilizing only a fragment of My Oracle Support’s potential. For the investment that has been made, using only a small subset of the capabilities offered in My Oracle Support leaves value on the table. There is much more available in My Oracle Support. Dozens of diagnostic tools and proactive health checks will keep verifying your Oracle environments against best practices that Oracle gathers every day thanks to our comprehensive knowledge management process. Automated patch recommendations will help prevent known issues, and upgrade planning and more is included in My Oracle Support. Why are you not utilizing all of these best practices, capabilities and tools? Is it because you don’t have time to invest 2-3 hours of your time to learn about the features? Simply because you think you can learn on the fly like I thought I could? Does learning on the fly how to properly use the Service Request escalation process when you already have critical issue sound like a good idea? My advice is: Invest your time now to learn how My Oracle Support can help you prevent issues on your systems. Learn how to find answers faster and resolve problems more efficiently. Understand how to properly complete a service request. Invest in Support training, offered at no additional cost to Oracle Premier Support customers. It will pay back quicker than you think. It will bring you more value than you think. Discover your advantage with Oracle Premier Support's Proactive Portfolio.

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• Why is x=x++ undefined?

  - by ugoren

  It's undefined because the it modifies x twice between sequence points. The standard says it's undefined, therefore it's undefined. That much I know. But why? My understanding is that forbidding this allows compilers to optimize better. This could have made sense when C was invented, but now seems like a weak argument. If we were to reinvent C today, would we do it this way, or can it be done better? Or maybe there's a deeper problem, that makes it hard to define consistent rules for such expressions, so it's best to forbid them? So suppose we were to reinvent C today. I'd like to suggest simple rules for expressions such as x=x++, which seem to me to work better than the existing rules. I'd like to get your opinion on the suggested rules compared to the existing ones, or other suggestions. Suggested Rules: Between sequence points, order of evaluation is unspecified. Side effects take place immediately. There's no undefined behavior involved. Expressions evaluate to this value or that, but surely won't format your hard disk (strangely, I've never seen an implementation where x=x++ formats the hard disk). Example Expressions x=x++ - Well defined, doesn't change x. First, x is incremented (immediately when x++ is evaluated), then it's old value is stored in x. x++ + ++x - Increments x twice, evaluates to 2*x+2. Though either side may be evaluated first, the result is either x + (x+2) (left side first) or (x+1) + (x+1) (right side first). x = x + (x=3) - Unspecified, x set to either x+3 or 6. If the right side is evaluated first, it's x+3. It's also possible that x=3 is evaluated first, so it's 3+3. In either case, the x=3 assignment happens immediately when x=3 is evaluated, so the value stored is overwritten by the other assignment. x+=(x=3) - Well defined, sets x to 6. You could argue that this is just shorthand for the expression above. But I'd say that += must be executed after x=3, and not in two parts (read x, evaluate x=3, add and store new value). What's the Advantage? Some comments raised this good point. It's not that I'm after the pleasure of using x=x++ in my code. It's a strange and misleading expression. What I want is to be able to understand complicated expressions. Normally, a complicated expression is no more than the sum of its parts. If you understand the parts and the operators combining them, you can understand the whole. C's current behavior seems to deviate from this principle. One assignment plus another assignment suddenly doesn't make two assignments. Today, when I look at x=x++, I can't say what it does. With my suggested rules, I can, by simply examining its components and their relations.

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• Multidimensional multiple-choice knapsack problem: find a feasible solution

  - by Onheiron

  My assignment is to use local search heuristics to solve the Multidimensional multiple-choice knapsack problem, but to do so I first need to find a feasible solution to start with. Here is an example problem with what I tried so far. Problem R1 R2 R3 RESOUCES : 8 8 8 GROUPS: G1: 11.0 3 2 2 12.0 1 1 3 G2: 20.0 1 1 3 5.0 2 3 2 G3: 10.0 2 2 3 30.0 1 1 3 Sorting strategies To find a starting feasible solution for my local search I decided to ignore maximization of gains and just try to fit the resources requirements. I decided to sort the choices (strategies) in each group by comparing their "distance" from the multidimensional space origin, thus calculating SQRT(R1^2 + R2^2 + ... + RN^2). I felt like this was a keen solution as it somehow privileged those choices with resouce usages closer to each other (e.g. R1:2 R2:2 R3:2 < R1:1 R2:2 R3:3) even if the total sum is the same. Doing so and selecting the best choice from each group proved sufficent to find a feasible solution for many[30] different benchmark problems, but of course I knew it was just luck. So I came up with the problem presented above which sorts like this: R1 R2 R3 RESOUCES : 8 8 8 GROUPS: G1: 12.0 1 1 3 < select this 11.0 3 2 2 G2: 20.0 1 1 3 < select this 5.0 2 3 2 G3: 30.0 1 1 3 < select this 10.0 2 2 3 And it is not feasible because the resources consmption is R1:3, R2:3, R3:9. The easy solution is to pick one of the second best choices in group 1 or 2, so I'll need some kind of iteration (local search[?]) to find the starting feasible solution for my local search solution. Here are the options I came up with Option 1: iterate choices I tried to find a way to iterate all the choices with a specific order, something like G1 G2 G3 1 1 1 2 1 1 1 2 1 1 1 2 2 2 1 ... believeng that feasible solutions won't be that far away from the unfeasible one I start with and thus the number of iterations will keep quite low. Does this make any sense? If yes, how can I iterate the choices (grouped combinations) of each group keeping "as near as possibile" to the previous iteration? Option 2: Change the comparation term I tried to think how to find a better variable to sort the choices on. I thought at a measure of how "precious" a resource is based on supply and demand, so that an higer demand of a more precious resource will push you down the list, but this didn't help at all. Also I thought there probably isn't gonna be such a comparsion variable which assures me a feasible solution at first strike. I there such a variable? If not, is there a better sorting criteria anyways? Option 3: implement any known sub-optimal fast solving algorithm Unfortunately I could not find any of such algorithms online. Any suggestion?

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• ORA-4031 Troubleshooting Tool ???

  - by Takeyoshi Sasaki

  ORA-4031 ???????????????????? SGA ????????????(??????)??????????????????????????????????????????????????? ORA-4031 ??????????????????? ORA-4031 Troubleshooting Tool ??????????? ORA-4031 Troubleshooting Tool ?? ORA-4031 Troubleshooting Tool ? ORA-4031 ????????? ORA-4031 ???????????????????????????????????WEB????????????????????????????????My Oracle Support ??????????????????????? ORA-4031 ??????????????????????????????ORA-4031 ?????????????????????????????? ORA-4031 Troubleshooting Tool ???????? My Oracle Support ?????? Diagnostic Tools Catalog ??  ORA-4031 Troubleshooting Tool ???????????????? ORA-4031 Troubleshooting Tool ??????????????? ORA-4031 Troubleshooting Tool ????? ???2??????????????? ORA-4031 ?????????????????????????????ORA-4031 Troubleshooting Tool ????????????????????????????????????????ORA-4031 ???????????????????? ??????????????? ORA-4031???????????? ????????????? ORA-4031 ?????? AWR???????????????????????????????????????????????????????????? ????·???????·???????????? ORA-4031 ?????????? ????????? SR ?????????????????????????? [ADR] ????·??????·?????????? [10g ???] AWR?????(STATSPACK????)???? ?????????? ORA-4031 ????????????????????????????????????????????? ORA-4031 ?????????????? ORA-4031 ??????1?1??????????? ORA-4031 Troubleshooting Tool ???????????(??????????????)???????? ORA-4031 ????????? ???????????????????????????????????????????????? ??????????????????????????????????????1)High Session_Cached_Cursor Setting Causing Excessive Consumption of Shared Pool???SESSION_CACHED_CURSOR ??????????????????????????????????????????????2)Insufficient SGA Free Memory at StartupThis issue could occur if in the init.ora parameters of your Alert log, (shared_pool_size + large_pool_size + java_pool_size + db_keep_cache_size + streams_pool_size + db_cache_size) / sga_target is greater than 90%.????????????????????????? ?????????????? shared_pool_size, large_pool_size, java_pool_size, db_keep_cache_size, streams_pool_size, db_cache_size ????? /sga_target ??? 90% ??????????????????sga_target ??? memory_target ??????????????????????????????????????????????????????????????????? shared_pool_size ???????????????????????????????????????????????????????????????????????(?????????)? sga_target ????????????????????????????????????????????????????????????? ?????????????????????????????????????????????1)In your Alert log,* Look for parameters under "System parameters with non-default values:". If session_cached_cursor * 2000 / shared_pool_size is greater than 10%, then session_cached_cursors are consuming significant shared_pool_size.??? ????????????? "System parameters with non-default values:" ????  session_cached_cursor * 2000 ??? shared_pool_size ? 10% ???????????????????????? ???2) In your Alert log, SGA Utilization (Sum of shared_pool_size, large_pool_size, java_pool_size, db_keep_cache_size, streams_pool_size and db_cache_size over sga_target) is 99%, which might be too high. ??? shared_pool_size, large_pool_size, java_pool_size, db_keep_cache_size, streams_pool_size and db_cache_size ???? sga_target ? 99% ???????????????????? ?????????????????????????????? My Oracle Support ??????????????????????????1)Decrease the parameter SESSION_CACHED_CURSORSSESSION_CACHED_CURSORS ???????????????????????2)Reduce the minimum values for the dynamic SGA components to allow memory manager to make changes as neededSGA ?????????????????(???)?????????????????? 2????????????????????? ORA-4031 Trobuleshooting Tool ????????????????????????????????????????? ORA-4031 Troubleshooting Tool ?????? ORA-4031 ??????????????????????ORA-4031 Troubleshooting Tool ???????????????????????????????????????????????????????ORA-4031 ????????????????????????????ORA-4031 ??????????????? ORA-4031 Troubleshooting Tool ?????????

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• What's the difference between find and findstr commands in Windows?

  - by Prashant Bhate

  In Windows, what are the differences between find and findstr commands? Both seems to search text in files: find c:\>find /? Searches for a text string in a file or files. FIND [/V] [/C] [/N] [/I] [/OFF[LINE]] "string" [[drive:][path]filename[ ...]] /V Displays all lines NOT containing the specified string. /C Displays only the count of lines containing the string. /N Displays line numbers with the displayed lines. /I Ignores the case of characters when searching for the string. /OFF[LINE] Do not skip files with offline attribute set. "string" Specifies the text string to find. [drive:][path]filename Specifies a file or files to search. If a path is not specified, FIND searches the text typed at the prompt or piped from another command. findstr c:\>findstr /? Searches for strings in files. FINDSTR [/B] [/E] [/L] [/R] [/S] [/I] [/X] [/V] [/N] [/M] [/O] [/P] [/F:file] [/C:string] [/G:file] [/D:dir list] [/A:color attributes] [/OFF[LINE]] strings [[drive:][path]filename[ ...]] /B Matches pattern if at the beginning of a line. /E Matches pattern if at the end of a line. /L Uses search strings literally. /R Uses search strings as regular expressions. /S Searches for matching files in the current directory and all subdirectories. /I Specifies that the search is not to be case-sensitive. /X Prints lines that match exactly. /V Prints only lines that do not contain a match. /N Prints the line number before each line that matches. /M Prints only the filename if a file contains a match. /O Prints character offset before each matching line. /P Skip files with non-printable characters. /OFF[LINE] Do not skip files with offline attribute set. /A:attr Specifies color attribute with two hex digits. See "color /?" /F:file Reads file list from the specified file(/ stands for console). /C:string Uses specified string as a literal search string. /G:file Gets search strings from the specified file(/ stands for console). /D:dir Search a semicolon delimited list of directories strings Text to be searched for. [drive:][path]filename Specifies a file or files to search. Use spaces to separate multiple search strings unless the argument is prefixed with /C. For example, 'FINDSTR "hello there" x.y' searches for "hello" or "there" in file x.y. 'FINDSTR /C:"hello there" x.y' searches for "hello there" in file x.y. Regular expression quick reference: . Wildcard: any character * Repeat: zero or more occurances of previous character or class ^ Line position: beginning of line $ Line position: end of line [class] Character class: any one character in set [^class] Inverse class: any one character not in set [x-y] Range: any characters within the specified range \x Escape: literal use of metacharacter x \<xyz Word position: beginning of word xyz\> Word position: end of word For full information on FINDSTR regular expressions refer to the online Command Reference.

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• T-SQL: Compute Subtotals For A Range Of Rows

  - by John Dibling

  MSSQL 2008. I am trying to construct a SQL statement which returns the total of column B for all rows where column A is between 2 known ranges. The range is a sliding window, and should be recomputed as it might be using a loop. Here is an example of what I'm trying to do, much simplified from my actual problem. Suppose I have this data: table: Test Year Sales ----------- ----------- 2000 200 2001 200 2002 200 2003 200 2004 200 2005 200 2006 200 2007 200 2008 200 2009 200 2010 200 2011 200 2012 200 2013 200 2014 200 2015 200 2016 200 2017 200 2018 200 2019 200 I want to construct a query which returns 1 row for every decade in the above table, like this: Desired Results: DecadeEnd TotalSales --------- ---------- 2009 2000 2010 2000 Where the first row is all the sales for the years 2000-2009, the second for years 2010-2019. The DecadeEnd is a sliding window that moves forward by a set ammount for each row in the result set. To illustrate, here is one way I can accomplish this using a loop: declare @startYear int set @startYear = (select top(1) [Year] from Test order by [Year] asc) declare @endYear int set @endYear = (select top(1) [Year] from Test order by [Year] desc) select @startYear, @endYear create table DecadeSummary (DecadeEnd int, TtlSales int) declare @i int -- first decade ends 9 years after the first data point set @i = (@startYear + 9) while @i <= @endYear begin declare @ttlSalesThisDecade int set @ttlSalesThisDecade = (select SUM(Sales) from Test where(Year <= @i and Year >= (@i-9))) insert into DecadeSummary values(@i, @ttlSalesThisDecade) set @i = (@i + 9) end select * from DecadeSummary This returns the data I want: DecadeEnd TtlSales ----------- ----------- 2009 2000 2018 2000 But it is very inefficient. How can I construct such a query?

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• How do I filter out NaN FLOAT values in Teradata SQL?

  - by Paul Hooper

  With the Teradata database, it is possible to load values of NaN, -Inf, and +Inf into FLOAT columns through Java. Unfortunately, once those values get into the tables, they make life difficult when writing SQL that needs to filter them out. There is no IsNaN() function, nor can you "CAST ('NaN' as FLOAT)" and use an equality comparison. What I would like to do is, SELECT SUM(VAL**2) FROM DTM WHERE NOT ABS(VAL) > 1e+21 AND NOT VAL = CAST ('NaN' AS FLOAT) but that fails with error 2620, "The format or data contains a bad character.", specifically on the CAST. I've tried simply "... AND NOT VAL = 'NaN'", which also fails for a similar reason (3535, "A character string failed conversion to a numeric value."). I cannot seem to figure out how to represent NaN within the SQL statement. Even if I could represent NaN successfully in an SQL statement, I would be concerned that the comparison would fail. According to the IEEE 754 spec, NaN = NaN should evaluate to false. What I really seem to need is an IsNaN() function. Yet that function does not seem to exist.

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• Need help with fixing Genetic Algorithm that's not evolving correctly

  - by EnderMB

  I am working on a maze solving application that uses a Genetic Algorithm to evolve a set of genes (within Individuals) to evolve a Population of Individuals that power an Agent through a maze. The majority of the code used appears to be working fine but when the code runs it's not selecting the best Individual's to be in the new Population correctly. When I run the application it outputs the following: Total Fitness: 380.0 - Best Fitness: 11.0 Total Fitness: 406.0 - Best Fitness: 15.0 Total Fitness: 344.0 - Best Fitness: 12.0 Total Fitness: 373.0 - Best Fitness: 11.0 Total Fitness: 415.0 - Best Fitness: 12.0 Total Fitness: 359.0 - Best Fitness: 11.0 Total Fitness: 436.0 - Best Fitness: 13.0 Total Fitness: 390.0 - Best Fitness: 12.0 Total Fitness: 379.0 - Best Fitness: 15.0 Total Fitness: 370.0 - Best Fitness: 11.0 Total Fitness: 361.0 - Best Fitness: 11.0 Total Fitness: 413.0 - Best Fitness: 16.0 As you can clearly see the fitnesses are not improving and neither are the best fitnesses. The main code responsible for this problem is here, and I believe the problem to be within the main method, most likely where the selection methods are called: package GeneticAlgorithm; import GeneticAlgorithm.Individual.Action; import Robot.Robot.Direction; import Maze.Maze; import Robot.Robot; import java.util.ArrayList; import java.util.Random; public class RunGA { protected static ArrayList tmp1, tmp2 = new ArrayList(); // Implementation of Elitism protected static int ELITISM_K = 5; // Population size protected static int POPULATION_SIZE = 50 + ELITISM_K; // Max number of Iterations protected static int MAX_ITERATIONS = 200; // Probability of Mutation protected static double MUTATION_PROB = 0.05; // Probability of Crossover protected static double CROSSOVER_PROB = 0.7; // Instantiate Random object private static Random rand = new Random(); // Instantiate Population of Individuals private Individual[] startPopulation; // Total Fitness of Population private double totalFitness; Robot robot = new Robot(); Maze maze; public void setElitism(int result) { ELITISM_K = result; } public void setPopSize(int result) { POPULATION_SIZE = result + ELITISM_K; } public void setMaxIt(int result) { MAX_ITERATIONS = result; } public void setMutProb(double result) { MUTATION_PROB = result; } public void setCrossoverProb(double result) { CROSSOVER_PROB = result; } /** * Constructor for Population */ public RunGA(Maze maze) { // Create a population of population plus elitism startPopulation = new Individual[POPULATION_SIZE]; // For every individual in population fill with x genes from 0 to 1 for (int i = 0; i < POPULATION_SIZE; i++) { startPopulation[i] = new Individual(); startPopulation[i].randGenes(); } // Evaluate the current population's fitness this.evaluate(maze, startPopulation); } /** * Set Population * @param newPop */ public void setPopulation(Individual[] newPop) { System.arraycopy(newPop, 0, this.startPopulation, 0, POPULATION_SIZE); } /** * Get Population * @return */ public Individual[] getPopulation() { return this.startPopulation; } /** * Evaluate fitness * @return */ public double evaluate(Maze maze, Individual[] newPop) { this.totalFitness = 0.0; ArrayList<Double> fitnesses = new ArrayList<Double>(); for (int i = 0; i < POPULATION_SIZE; i++) { maze = new Maze(8, 8); maze.fillMaze(); fitnesses.add(startPopulation[i].evaluate(maze, newPop)); //this.totalFitness += startPopulation[i].evaluate(maze, newPop); } //totalFitness = (Math.round(totalFitness / POPULATION_SIZE)); StringBuilder sb = new StringBuilder(); for(Double tmp : fitnesses) { sb.append(tmp + ", "); totalFitness += tmp; } // Progress of each Individual //System.out.println(sb.toString()); return this.totalFitness; } /** * Roulette Wheel Selection * @return */ public Individual rouletteWheelSelection() { // Calculate sum of all chromosome fitnesses in population - sum S. double randNum = rand.nextDouble() * this.totalFitness; int i; for (i = 0; i < POPULATION_SIZE && randNum > 0; ++i) { randNum -= startPopulation[i].getFitnessValue(); } return startPopulation[i-1]; } /** * Tournament Selection * @return */ public Individual tournamentSelection() { double randNum = rand.nextDouble() * this.totalFitness; // Get random number of population (add 1 to stop nullpointerexception) int k = rand.nextInt(POPULATION_SIZE) + 1; int i; for (i = 1; i < POPULATION_SIZE && i < k && randNum > 0; ++i) { randNum -= startPopulation[i].getFitnessValue(); } return startPopulation[i-1]; } /** * Finds the best individual * @return */ public Individual findBestIndividual() { int idxMax = 0; double currentMax = 0.0; double currentMin = 1.0; double currentVal; for (int idx = 0; idx < POPULATION_SIZE; ++idx) { currentVal = startPopulation[idx].getFitnessValue(); if (currentMax < currentMin) { currentMax = currentMin = currentVal; idxMax = idx; } if (currentVal > currentMax) { currentMax = currentVal; idxMax = idx; } } // Double check to see if this has the right one //System.out.println(startPopulation[idxMax].getFitnessValue()); // Maximisation return startPopulation[idxMax]; } /** * One Point Crossover * @param firstPerson * @param secondPerson * @return */ public static Individual[] onePointCrossover(Individual firstPerson, Individual secondPerson) { Individual[] newPerson = new Individual[2]; newPerson[0] = new Individual(); newPerson[1] = new Individual(); int size = Individual.SIZE; int randPoint = rand.nextInt(size); int i; for (i = 0; i < randPoint; ++i) { newPerson[0].setGene(i, firstPerson.getGene(i)); newPerson[1].setGene(i, secondPerson.getGene(i)); } for (; i < Individual.SIZE; ++i) { newPerson[0].setGene(i, secondPerson.getGene(i)); newPerson[1].setGene(i, firstPerson.getGene(i)); } return newPerson; } /** * Uniform Crossover * @param firstPerson * @param secondPerson * @return */ public static Individual[] uniformCrossover(Individual firstPerson, Individual secondPerson) { Individual[] newPerson = new Individual[2]; newPerson[0] = new Individual(); newPerson[1] = new Individual(); for(int i = 0; i < Individual.SIZE; ++i) { double r = rand.nextDouble(); if (r > 0.5) { newPerson[0].setGene(i, firstPerson.getGene(i)); newPerson[1].setGene(i, secondPerson.getGene(i)); } else { newPerson[0].setGene(i, secondPerson.getGene(i)); newPerson[1].setGene(i, firstPerson.getGene(i)); } } return newPerson; } public double getTotalFitness() { return totalFitness; } public static void main(String[] args) { // Initialise Environment Maze maze = new Maze(8, 8); maze.fillMaze(); // Instantiate Population //Population pop = new Population(); RunGA pop = new RunGA(maze); // Instantiate Individuals for Population Individual[] newPop = new Individual[POPULATION_SIZE]; // Instantiate two individuals to use for selection Individual[] people = new Individual[2]; Action action = null; Direction direction = null; String result = ""; /*result += "Total Fitness: " + pop.getTotalFitness() + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue();*/ // Print Current Population System.out.println("Total Fitness: " + pop.getTotalFitness() + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue()); // Instantiate counter for selection int count; for (int i = 0; i < MAX_ITERATIONS; i++) { count = 0; // Elitism for (int j = 0; j < ELITISM_K; ++j) { // This one has the best fitness newPop[count] = pop.findBestIndividual(); count++; } // Build New Population (Population size = Steps (28)) while (count < POPULATION_SIZE) { // Roulette Wheel Selection people[0] = pop.rouletteWheelSelection(); people[1] = pop.rouletteWheelSelection(); // Tournament Selection //people[0] = pop.tournamentSelection(); //people[1] = pop.tournamentSelection(); // Crossover if (rand.nextDouble() < CROSSOVER_PROB) { // One Point Crossover //people = onePointCrossover(people[0], people[1]); // Uniform Crossover people = uniformCrossover(people[0], people[1]); } // Mutation if (rand.nextDouble() < MUTATION_PROB) { people[0].mutate(); } if (rand.nextDouble() < MUTATION_PROB) { people[1].mutate(); } // Add to New Population newPop[count] = people[0]; newPop[count+1] = people[1]; count += 2; } // Make new population the current population pop.setPopulation(newPop); // Re-evaluate the current population //pop.evaluate(); pop.evaluate(maze, newPop); // Print results to screen System.out.println("Total Fitness: " + pop.totalFitness + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue()); //result += "\nTotal Fitness: " + pop.totalFitness + " - Best Fitness: " + pop.findBestIndividual().getFitnessValue(); } // Best Individual Individual bestIndiv = pop.findBestIndividual(); //return result; } } I have uploaded the full project to RapidShare if you require the extra files, although if needed I can add the code to them here. This problem has been depressing me for days now and if you guys can help me I will forever be in your debt.

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• Find the "largest" dense sub matrix in a large sparse matrix

  - by BCS

  Given a large sparse matrix (say 10k+ by 1M+) I need to find a subset, not necessarily continuous, of the rows and columns that form a dense matrix (all non-zero elements). I want this sub matrix to be as large as possible (not the largest sum, but the largest number of elements) within some aspect ratio constraints. Are there any known exact or aproxamate solutions to this problem? A quick scan on Google seems to give a lot of close-but-not-exactly results. What terms should I be looking for? edit: Just to clarify; the sub matrix need not be continuous. In fact the row and column order is completely arbitrary so adjacency is completely irrelevant. A thought based on Chad Okere's idea Order the rows from largest count to smallest count (not necessary but might help perf) Select two rows that have a "large" overlap Add all other rows that won't reduce the overlap Record that set Add whatever row reduces the overlap by the least Repeat at #3 until the result gets to small Start over at #2 with a different starting pair Continue until you decide the result is good enough

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• Python recursive function error: "maximum recursion depth exceeded"

  - by user283169

  I solved Problem 10 of Project Euler with the following code, which works through brute force: def isPrime(n): for x in range(2, int(n**0.5)+1): if n % x == 0: return False return True def primeList(n): primes = [] for i in range(2,n): if isPrime(i): primes.append(i) return primes def sumPrimes(primelist): prime_sum = sum(primelist) return prime_sum print (sumPrimes(primeList(2000000))) The three functions work as follows: isPrime checks whether a number is a prime; primeList returns a list containing a set of prime numbers for a certain range with limit 'n', and; sumPrimes sums up the values of all numbers in a list. (This last function isn't needed, but I liked the clarity of it, especially for a beginner like me.) I then wrote a new function, primeListRec, which does exactly the same thing as primeList, to help me better understand recursion: def primeListRec(i, n): primes = [] #print i if (i != n): primes.extend(primeListRec(i+1,n)) if (isPrime(i)): primes.append(i) return primes return primes The above recursive function worked, but only for very small values, like '500'. The function caused my program to crash when I put in '1000'. And when I put in a value like '2000', Python gave me this: RuntimeError: maximum recursion depth exceeded. What did I do wrong with my recursive function? Or is there some specific way to avoid a recursion limit?

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• Python progression path - From apprentice to guru

  - by Morlock

  Hi all, I've been learning, working, and playing with Python for a year and a half now. As a biologist slowly making the turn to bio-informatics, this language has been a the very core of all the major contributions I have made in the lab. (bash and R scripts have helped some too. My C++ capabilities are very not functional yet). I more or less fell in love with the way Python permits me to express beautiful solutions and also with the semantics of the language that allows such a natural flow from thoughts to workable code. What I would like to know from you is your answer to a kind of question I have seldom seen in this or other forums. Let me sum up what I do NOT want to ask first ;) I don't want to know how to QUICKLY learn Python Nor do I want to find out the best way to get acquainted with the language Finally, I don't want to know a 'one trick that does it all' approach. What I do want to know your opinion about, is: What are the steps YOU would recommend to a Python journeyman, from apprenticeship to guru status (feel free to stop wherever your expertise dictates it), in order that one IMPROVES CONSTANTLY, becoming a better and better Python coder, one step at a time. The kind of answers I would enjoy (but feel free to surprise the readership :P ), is formatted more or less like this: Read this (eg: python tutorial), pay attention to that kind of details Code for so manytime/problems/lines of code Then, read this (eg: this or that book), but this time, pay attention to this Tackle a few real-life problems Then, proceed to reading Y. Be sure to grasp these concepts Code for X time Come back to such and such basics or move further to... (you get the point :) This process depicts an iterative Learn/Code cycle, and I really care about knowing your opinion on what exactly one should pay attention to, at various stages, in order to progress CONSTANTLY (with due efforts, of course). If you come from a specific field of expertise, discuss the path you see as appropriate in this field. Thanks a lot for sharing your opinions and good Python coding!

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• LINQ-to-SQL: ExecuteQuery(Type, String) populates one field, but not the other

  - by Daniel Schaffer

  I've written an app that I use as an agent to query data from a database and automatically load it into my distributed web cache. I do this by specifying an sql query and a type in a configuration. The code that actually does the querying looks like this: List<Object> result = null; try { result = dc.ExecuteQuery(elementType, entry.Command).OfType<Object>().ToList(); } catch (Exception ex) { HandleException(ex, WebCacheAgentLogEvent.DatabaseExecutionError); continue; } elementType is a System.Type created from the type specified in the configuration (using Type.GetType()), and entry.Command is the SQL query. The specific entity type I'm having an issue with looks like this: public class FooCount { [Column(Name = "foo_id")] public Int32 FooId { get; set; } [Column(Name = "count")] public Int32 Count { get; set; } } The SQL query looks like this: select foo_id as foo_id, sum(count) as [count] from foo_aggregates group by foo_id order by foo_id For some reason, when the query is executed, the "Count" property ends up populated, but not the "FooId" property. I tried running the query myself, and the correct column names are returned, and the column names match up with what I've specified in my mapping attributes. Help!

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• Kruskal-Wallis test with details on pairwise comparisons

  - by dalloliogm

  The standard stats::kruskal.test module allows to calculate the kruskal-wallis test on a dataset: >>> data(diamonds) >>> kruskal.test.test(price~carat, data=diamonds) Kruskal-Wallis rank sum test data: price by carat by color Kruskal-Wallis chi-squared = 50570.15, df = 272, p-value < 2.2e-16 this is correct, it is giving me a probability that all the groups in the data have the same mean. However, I would like to have the details for each pair comparison, like if diamonds of colors D and E have the same mean price, as some other softwares do (SPSS) when you ask for a Kruskal test. I have found kruskalmc from the package pgirmess which allows me to do what I want to do: > kruskalmc(diamonds$price, diamonds$color) Multiple comparison test after Kruskal-Wallis p.value: 0.05 Comparisons obs.dif critical.dif difference D-E 571.7459 747.4962 FALSE D-F 2237.4309 751.5684 TRUE D-G 2643.1778 726.9854 TRUE D-H 4539.4392 774.4809 TRUE D-I 6002.6286 862.0150 TRUE D-J 8077.2871 1061.7451 TRUE E-F 2809.1767 680.4144 TRUE E-G 3214.9237 653.1587 TRUE E-H 5111.1851 705.6410 TRUE E-I 6574.3744 800.7362 TRUE E-J 8649.0330 1012.6260 TRUE F-G 405.7470 657.8152 FALSE F-H 2302.0083 709.9533 TRUE F-I 3765.1977 804.5390 TRUE F-J 5839.8562 1015.6357 TRUE G-H 1896.2614 683.8760 TRUE G-I 3359.4507 781.6237 TRUE G-J 5434.1093 997.5813 TRUE H-I 1463.1894 825.9834 TRUE H-J 3537.8479 1032.7058 TRUE I-J 2074.6585 1099.8776 TRUE However, this package only allows for one categoric variable (e.g. I can't study the prices clustered by color and by carat, as I can do with kruskal.test), and I don't know anything about the pgirmess package, whether it is maintained or not, or if it is tested. Can you recommend me a package to execute the Kruskal-Wallis test which returns details for every comparison? How would you handle the problem?

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