Search Results

Search found 30575 results on 1223 pages for 'number systems'.

Page 170/1223 | < Previous Page | 166 167 168 169 170 171 172 173 174 175 176 177  | Next Page >

• Synergy - easy share of keyboard and mouse between multiple computers

  Did you ever have the urge to share one set of keyboard and mouse between multiple machines? If so, please read on... Using multiple machines Honestly, as a software craftsman it is my daily business to run multiple machines - either physical or virtual - to be able to solve my customers' requirements. Recent hardware equipment allows this very easily. For laptops it's a no-brainer to attach a second or even a third screen in order to extend your native display. This works quite handy and in my case I used to attached two additional screens - one via HD15 connector, the other via HDMI. But... as it's a laptop and therefore a mobile unit there are slight restrictions. Detaching and re-attaching all cables when changing locations is one of them but hardware limitations, too. After all, it's a laptop and not a workstation. I guess, that anyone working in IT (or ICT) has more than one machine at their workplace or their home office and at least I find it quite annoying to have multiple sets of keyboard and mouse conquering my remaining space on my desk. Despite the ugly looks of all those cables and whatsoever 'chaos of distraction' I prefer a more clean solution and working environment. This allows me to actually focus on my work and tasks to do rather than to worry about choosing the right combination of keyboard/mouse. My current workplace is a patch work of various pieces of hardware (approx. 2-3 years): DIY desktop on Ubuntu 12.04 64-bit, Core2 Duo (E7400, 2.8GHz), 4GB RAM, 2x 250GB HDD, nVidia GPU 512MB Dell Inspiron 1525 on Windows 8 64-bit, 4GB RAM, 200GB HDD HP Compaq 6720s on Windows Vista 32-bit, Core2 Duo (T5670, 1.8GHz), 2GB RAM, 160GB HDD Mac mini on Mac OS X 10.7, Core i5 (2.3 GHz), 2GB RAM, 500GB HDD I know... Not the latest and greatest but a decent combination to work with. New system(s) is/are already on the shopping list but I live in the 'wrong' country to buy computer hardware. So, the next trip abroad will provide me with some new stuff. Using multiple operating systems The list of hardware above already names different operating systems, and actually I have only one preference: Linux. But still my job as a software craftsman for Visual FoxPro and .NET development requires other OSes, too. Not a big deal, it's just like this. Additionally to those physical machines, there are a bunch of virtual machines around. Most of them running either Windows XP or Windows 7. Since years I have the practice that each development for one customer is isolated into its own virtual machine and environment. This keeps it clean and version-safe. But as you can easily imagine with that setup there are a couple of constraints referring to keyboard and mouse. Usually, those systems require their own pieces of hardware attached. As stated, I don't like clutter on my desk's surface, so a cross-platform solution has to come in here. In the past, I tried it with various applications, hardware or network protocols like X11, RDP, NX, TeamViewer, RAdmin, KVM switch, etc. but the problem in this case is that they either allow you to remotely connect to the other system or exclusively 'bind' your peripherals to the active system. Not optimal after all. Synergy to the rescue Quote from their website: "Synergy lets you easily share your mouse and keyboard between multiple computers on your desk, and it's Free and Open Source. Just move your mouse off the edge of one computer's screen on to another. You can even share all of your clipboards. All you need is a network connection. Synergy is cross-platform (works on Windows, Mac OS X and Linux)." Yep, that's it! All I need for my setup here... Actually, I couldn't believe it myself that I didn't stumble over synergy earlier but 'Get over it' and there we go. And despite the fact that it is Open Source, no, it's also for free. Donations for the developers are very welcome and recently they introduced Synergy Premium. A possibility to buy so-called premium votes that can be used to put more weight / importance on specific issues or bugs that you would like the developers to look into. Installation and configuration Simply download the installation packages for your systems of choice, run the installer and enter some minor information about your network setup. I chose my desktop machine for the role of the Synergy server and configured my screen setup as follows: The screen setup allows you currently to build or connect up to 15 machines. The number of screens can be higher as those machine might have multiple screens physically attached. Synergy takes this into the overall calculations and simply works as expected. I tried it for fun with a second monitor each connected to both laptops to have a total number of 6 active screens. No flaws after all - stunning! All the other machines are configured as clients like so: Side note: The screenshot was taken on Windows 8 and pasted via clipboard into Gimp running on Ubuntu. Resume Synergy is now definitely in my box of tools for my daily work, and amongst the first pieces of software I install after the operating system. It just simplifies my life and cleans my desk. Never again without Synergy!Now, only waiting for an Android version to integrate my Galaxy Tab 10.1, too. ;-) Please, check out that superb product and enjoy sharing one keyboard, one mouse and one clipboard between your various machines and operating systems.

  Read the article

• eSTEP TechCast - December 2012

  - by Cinzia Mascanzoni

  Join our next eSTEP TechCast will be on Thursday, 06. December 2012, 11:00 - 12:00 GMT (12:00 - 13:00 CET; 15:00 - 16:00 GST) Title: Innovations with Oracle Solaris Cluster 4 In this webcast we will focus at the integration of the cluster software with the IPS packaging system of Solaris 11, which makes installing and updating the software much easier and much more reliable, especially with virtualization technologies involved. Our webcast will also reflect new versions of Oracle Solaris Cluster if they will be announced in the meantime.Call Info: Call-in-toll-free number: 08006948154 (United Kingdom) Call-in-toll-free number: +44-2081181001 (United Kingdom) Show global numbers Conference Code: 803 594 3 Security Passcode: 9876 Webex Info (Oracle Web Conference) Meeting Number: 255 760 510 Meeting Password: tech2011 Playback / Recording / Archive: The webcasts will be recorded and will be available shortly after the event in the eSTEP portal under the Events tab, where you could find also material from already delivered eSTEP TechCasts. Use your email-adress and PIN: eSTEP_2011 to get access. 

  Read the article

• What encryption algorithm/package should I use in a betting game?

  - by user299648

  I have a betting type site where I publish a number (between 0-100) that is encrypted. Then after a period of time, I would review what the number is and prove it with a key to decrypt the encrypted number to prove that I'm not cheating. I also want it to be easily verifiable by an average user. What encryption algorithm/technique/package should I use? I'm no expert on cryptography. There seems to be so many options out there and I'm not sure what to use. python friendly is a plus.

  Read the article

• What is the logic behind this C Program?

  - by iamanimesh19

  Here is a small piece of program (14 lines of program) which counts the number of bits set in a number. Input-Output -- 0--0(0000000), 5--2(0000101), 7--3(0000111) int CountBits (unsigned int x) { static unsigned int mask[] = { 0x55555555, 0x33333333, 0x0F0F0F0F, 0x00FF00FF, 0x0000FFFF } ; int i ; int shift ; /* Number of positions to shift to right*/ for (i =0, shift =1; i < 5; i ++, shift *= 2) x = (x & mask[i ])+ ( ( x >> shift) & mask[i]); return x; } Can someone explain the algorithm used here/why this works?

  Read the article

• xor of sequence of numbers

  - by ArG0NaUt

  You are given with a sequence of natural numbers, you can add any natural number to any number in the sequence such that their xor becomes zero. Your goal is to minimize the sum of added numbers. e.g. Consider the following examples : sequence : 1, 3 answer : 2, adding 2 to 1 we get 3^3=0. sequence : 10, 4, 5, 1 answer: 6, adding 3 to 10 & 3 to 8 we get 13^4^8^1 = 0. sequence : 4, 4 answer : 0, since 4^4 = 0. I tried working on binary representations of sequence number but it got so complex. I want to know if there is any simple and efficient way to solve this problem.

  Read the article

• Implement Fast Inverse Square Root in Javascript?

  - by BBz

  The Fast Inverse Square Root from Quake III seems to use a floating-point trick. As I understand, floating-point representation can have some different implementations. So is it possible to implement the Fast Inverse Square Root in Javascript? Would it return the same result? float Q_rsqrt(float number) { long i; float x2, y; const float threehalfs = 1.5F; x2 = number * 0.5F; y = number; i = * ( long * ) &y; i = 0x5f3759df - ( i >> 1 ); y = * ( float * ) &i; y = y * ( threehalfs - ( x2 * y * y ) ); return y; }

  Read the article

• How Would You Design This Table?

  - by sooprise

  I have to create a table where each row needs to store 50 number values. Each row will always need to store 50 number values. If this was a smaller number of values, I would just make fields for each of the values, but because there are 50, this approach seems a bit cumbersome (but since it will always be 50 values, maybe this is the correct approach?). Is there a way to store an array of values in a field? This seems like a nice solution, but the concept is almost identical to creating a relational database.

  Read the article

• Scuttlebutt Reconciliation from "Efficient Reconciliation and Flow Control for Anti-Entropy Protocols"

  - by Maus

  This question might be more suited to math.stackexchange.com, but here goes: Their Version Reconciliation takes two parts-- first the exchange of digests, and then an exchange of updates. I'll first paraphrase the paper's description of each step. To exchange digests, two peers send one another a set of pairs-- (peer, max_version) for each peer in the network, and then each one responds with a set of deltas. The deltas look like: (peer, key, value, version), for all tuples for which peer's state maps the key to the given value and version, and the version number is greater than the maximum version number peer has seen. This seems to require that each node remember the state of each other node, and the highest version number and ID each node has seen. Question Why must we iterate through all peers to exchange information between p and q?

  Read the article

• which way should I look at visits by region in Google Analytics?

  - by Drai

  I need to generate a report for only the Americas in Google Analytics. When I create an advanced segment that includes Continent Exactly Matching Americas I get one number, If I create the segment that includes sub-Continent region Includes America I get a slightly different number, And if I look at all visits but choose Demographicslocationand segment by sub-continent region I get yet a 3rd number! (Note: this is because it also includes Caribbean) All are only different by around 1% of traffic. What is the most accurate way to do this, or should I just pick a way and be consistent?

  Read the article

• What "version naming convention" do you use?

  - by rjstelling

  Are different version naming conventions suited to different projects? What do you use and why? Personally, I prefer a build number in hexadecimal (e.g 11BCF), this should be incremented very regularly. And then for customers a simple 3 digit version number, i.e. 1.1.3. 1.2.3 (11BCF) <- Build number, should correspond with a revision in source control ^ ^ ^ | | | | | +--- Minor bugs, spelling mistakes, etc. | +----- Minor features, major bug fixes, etc. +------- Major version, UX changes, file format changes, etc.

  Read the article

• Creating meaningful and engaging quests

  - by user384918

  Kill X number of monsters. Gather Y number of items (usually by killing X number of monsters). Deliver this NPC's package to this other NPC who is far far away. etc. Yeah. These quests are easy to implement, easy to complete, but also very boring after the first few times. It's kind of disingenuous to call them quests really; they're more like chores or errands. What ideas for quests have people seen that were well designed, immersive, and rewarding? What specific things did the developers do that made it so? What are some ideas you would use (or have used) to make quests more interesting?

  Read the article

• How can I estimate the entropy of a password?

  - by Wug

  Having read various resources about password strength I'm trying to create an algorithm that will provide a rough estimation of how much entropy a password has. I'm trying to create an algorithm that's as comprehensive as possible. At this point I only have pseudocode, but the algorithm covers the following: password length repeated characters patterns (logical) different character spaces (LC, UC, Numeric, Special, Extended) dictionary attacks It does NOT cover the following, and SHOULD cover it WELL (though not perfectly): ordering (passwords can be strictly ordered by output of this algorithm) patterns (spatial) Can anyone provide some insight on what this algorithm might be weak to? Specifically, can anyone think of situations where feeding a password to the algorithm would OVERESTIMATE its strength? Underestimations are less of an issue. The algorithm: // the password to test password = ? length = length(password) // unique character counts from password (duplicates discarded) uqlca = number of unique lowercase alphabetic characters in password uquca = number of uppercase alphabetic characters uqd = number of unique digits uqsp = number of unique special characters (anything with a key on the keyboard) uqxc = number of unique special special characters (alt codes, extended-ascii stuff) // algorithm parameters, total sizes of alphabet spaces Nlca = total possible number of lowercase letters (26) Nuca = total uppercase letters (26) Nd = total digits (10) Nsp = total special characters (32 or something) Nxc = total extended ascii characters that dont fit into other categorys (idk, 50?) // algorithm parameters, pw strength growth rates as percentages (per character) flca = entropy growth factor for lowercase letters (.25 is probably a good value) fuca = EGF for uppercase letters (.4 is probably good) fd = EGF for digits (.4 is probably good) fsp = EGF for special chars (.5 is probably good) fxc = EGF for extended ascii chars (.75 is probably good) // repetition factors. few unique letters == low factor, many unique == high rflca = (1 - (1 - flca) ^ uqlca) rfuca = (1 - (1 - fuca) ^ uquca) rfd = (1 - (1 - fd ) ^ uqd ) rfsp = (1 - (1 - fsp ) ^ uqsp ) rfxc = (1 - (1 - fxc ) ^ uqxc ) // digit strengths strength = ( rflca * Nlca + rfuca * Nuca + rfd * Nd + rfsp * Nsp + rfxc * Nxc ) ^ length entropybits = log_base_2(strength) A few inputs and their desired and actual entropy_bits outputs: INPUT DESIRED ACTUAL aaa very pathetic 8.1 aaaaaaaaa pathetic 24.7 abcdefghi weak 31.2 H0ley$Mol3y_ strong 72.2 s^fU¬5ü;y34G< wtf 88.9 [a^36]* pathetic 97.2 [a^20]A[a^15]* strong 146.8 xkcd1** medium 79.3 xkcd2** wtf 160.5 * these 2 passwords use shortened notation, where [a^N] expands to N a's. ** xkcd1 = "Tr0ub4dor&3", xkcd2 = "correct horse battery staple" The algorithm does realize (correctly) that increasing the alphabet size (even by one digit) vastly strengthens long passwords, as shown by the difference in entropy_bits for the 6th and 7th passwords, which both consist of 36 a's, but the second's 21st a is capitalized. However, they do not account for the fact that having a password of 36 a's is not a good idea, it's easily broken with a weak password cracker (and anyone who watches you type it will see it) and the algorithm doesn't reflect that. It does, however, reflect the fact that xkcd1 is a weak password compared to xkcd2, despite having greater complexity density (is this even a thing?). How can I improve this algorithm? Addendum 1 Dictionary attacks and pattern based attacks seem to be the big thing, so I'll take a stab at addressing those. I could perform a comprehensive search through the password for words from a word list and replace words with tokens unique to the words they represent. Word-tokens would then be treated as characters and have their own weight system, and would add their own weights to the password. I'd need a few new algorithm parameters (I'll call them lw, Nw ~= 2^11, fw ~= .5, and rfw) and I'd factor the weight into the password as I would any of the other weights. This word search could be specially modified to match both lowercase and uppercase letters as well as common character substitutions, like that of E with 3. If I didn't add extra weight to such matched words, the algorithm would underestimate their strength by a bit or two per word, which is OK. Otherwise, a general rule would be, for each non-perfect character match, give the word a bonus bit. I could then perform simple pattern checks, such as searches for runs of repeated characters and derivative tests (take the difference between each character), which would identify patterns such as 'aaaaa' and '12345', and replace each detected pattern with a pattern token, unique to the pattern and length. The algorithmic parameters (specifically, entropy per pattern) could be generated on the fly based on the pattern. At this point, I'd take the length of the password. Each word token and pattern token would count as one character; each token would replace the characters they symbolically represented. I made up some sort of pattern notation, but it includes the pattern length l, the pattern order o, and the base element b. This information could be used to compute some arbitrary weight for each pattern. I'd do something better in actual code. Modified Example: Password: 1234kitty$$$$$herpderp Tokenized: 1 2 3 4 k i t t y $ $ $ $ $ h e r p d e r p Words Filtered: 1 2 3 4 @W5783 $ $ $ $ $ @W9001 @W9002 Patterns Filtered: @P[l=4,o=1,b='1'] @W5783 @P[l=5,o=0,b='$'] @W9001 @W9002 Breakdown: 3 small, unique words and 2 patterns Entropy: about 45 bits, as per modified algorithm Password: correcthorsebatterystaple Tokenized: c o r r e c t h o r s e b a t t e r y s t a p l e Words Filtered: @W6783 @W7923 @W1535 @W2285 Breakdown: 4 small, unique words and no patterns Entropy: 43 bits, as per modified algorithm The exact semantics of how entropy is calculated from patterns is up for discussion. I was thinking something like: entropy(b) * l * (o + 1) // o will be either zero or one The modified algorithm would find flaws with and reduce the strength of each password in the original table, with the exception of s^fU¬5ü;y34G<, which contains no words or patterns.

  Read the article

• Html5 games, what is the standard dimension to use?

  - by aoi

  I am trying to make html5 games to be played on the browser(not offline apps), and I am trying to support the maximum number of platforms, hence I need to know what dimension should I use for the game canvas so that it works in the most number of places. Also is there anyway to "scale" a large game to fit in the tiny size of iphone(around 320x356px I think). By "scale" I don't mean to actually resize just the canvas, as because that can mess up the coordinate based calculations, and for a large number of objects, re-positioning based on canvas size can be a real hassle.

  Read the article

• If you should only have one assertion per test; how to test multiple inputs?

  - by speg

  I'm trying to build up some test cases, and have read that you should try and limit the number of assertions per test case. So my question is, what is the best way to go about testing a function w/ multiple inputs. For example, I have a function that parses a string from the user and returns the number of minutes. The string can be in the form "5w6h2d1m", where w, h, d, m correspond to the number of weeks, hours, days, and minutes. If I wanted to follow the '1 assertion per test rule' I'd have to make multiple tests for each variation of input? That seems silly so instead I just have something like: self.assertEqual(parse_date('5m'), 5) self.assertEqual(parse_date('5h'), 300) self.assertEqual(parse_date('5d') ,7200) self.assertEqual(parse_date('1d4h20m'), 1700) In the one test case. Is there a better way?

  Read the article

• Now Every Thursday Morning - Silverlight TV

  It has been 7 weeks since Silverlight TV kicked off its first episode with Keith Smith. Since then we have posted a total of 12 shows on a variety of topics. Here are some interesting numbers from the show: 12 The number of episodes we have aired in since the debut. 145 The number of comments our viewers have left on Channel 9 703 How many followers @SilverlightTv has on Twitter 333,000 + The number of views Silverlight TV has had in 7 weeks! Thank you so much for watching! ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

  Read the article

• How do I count Internal Logical Files (ILF) and External Inputs (EI) for a dynamic form entry page?

  - by DmytroL

  Assuming I have an applicant information entry screen, the number and types of fields on which can be defined by the system administrator, how do I go about counting the number of Internal Logical Files (ILFs) and Data Element Types (DETs) for the related data functions? So far I have come up with something like this: ILF #1 (control information): Field Metadata, 1 RET, ~3 DET (name, type, mandatory) ILF #2 (business data): Applicant Data, most likely 1 RET, but how many DET? Of course I could count it as 2 DET (Field ref, Value), but I am not sure that would be correct And when it comes to an External Input (EI), say, "Add New Applicant", things become even more complicated, because the number of DET corresponding to the user-editable fields is totally dependent on the control information in ILF #1, and I am out of ideas here... Anyone fancy to help with that? Thanks in advance!

  Read the article

• Is 500 million lines of code even remotely possible? [on hold]

  - by kmote

  The New York Times is reporting that the Healthcare.gov website contains "about 500 million lines of software code." This number, attributed to "one specialist", and widely repeated across the interwebs, seems incredibly far-fetched (even assuming a large fraction of that number includes standard libraries). If this is an accurate estimate, it would truly be staggering (as this fascinating infographic vividly reveals). I realize StackExchange:Programmers isn't Snopes.com, but I'd like to find out if anyone here believes this is even remotely possible. I'd like to know if there is a plausible system of accounting (using examples from publicly available data, if possible) that could lead someone to conclude that such an estimate is within the realm of reason. How could a codebase (by any measure) sum up to such an exhorbitant number of code lines?

  Read the article

• Failed to allocate memory - What is it trying to say?

  - by asprin

  In my early days of programming I often used to get memory related fatal errors in the following format: Fatal error: Allowed memory size of <some big number> bytes exhausted (tried to allocate <some small number> bytes) in /path/to/filename.php on line <some line number> I'm a little embarrassed to state that even though I have figured out how to solve them and take steps to avoid them altogether, I'm still not quite sure what exactly does the message translate to in simple words. For example, if I get a message such as: Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 4000 bytes) in ........ on line 34 As things stand at the moment, I assume it to be stating that the script consumes 67108864 bytes of data, but only 4000 bytes are available during runtime. Am I right in my assumption? If not, what's the correct interpretation?

  Read the article

• What techniques can I use to render very large numbers of objects more efficiently in OpenGL?

  - by Luke

  You can think of my application as drawing a very large ball-and-stick diagram (or graph). At times, this graph can get very large, where the number of elements even outnumbers the pixels on the screen. Currently I am simply passing all of my textures (as GL_POINTS) and lines to the graphics card using VBO's. When the number of elements outnumbers the number of pixels, is this the most efficient way to do this? Or should I do some calculations on the CPU side before handing everything over to the GPU? If it matters, I do use GL_DEPTH_TEST and GL_ALPHA_TEST. I do some alpha blending, but probably not enough to make a huge performance difference. My scene can be static at times, but the user has control over a typical arc-ball camera and can pan, rotate, or zoom. It is during these operations that performance degradation is noticeable.

  Read the article

• What encryption algorithm/package should I use in a betting game type situation?

  - by user299648

  I have a betting type site where I publish a number (between 0-100) that is encrypted. Then after a period of time, I would review what the number is and prove it with a key to decrypt the encrypted number to prove that I'm not cheating. I also want it to be easily verifiable by an average user. What encryption algorithm/technique/package should I use? I'm no expert on cryptography. There seems to be so many options out there and I'm not sure what to use. python friendly is a plus.

  Read the article

• PHP error log does not display script names nor does it display the errors' line numbers [migrated]

  - by gnxtech3

  I think the title is self-explanatory, and my Google-fu isn't bringing up anything useful. I'm working on a new host, and my php error log only displays the error itself, not which script is the offender, nor which line number the error is occurring on. Makes it a tad difficult to debug, especially since there's only 1 error in the script. More info: I'm not using a custom error handler that I'm aware of. This is a standard Wordpress install. The error was [27-Aug-2012 19:22:36 UTC] PHP NOTICE: Trying to get property of non-object. Just no script name or line number in the error I found that Wordpress' error logging contained the information to debug the problem, but that doesn't explain why the log didn't contain line number or script.

  Read the article

• ????: PostgreSQL??Oracle RAC????

  - by Kumiko Fujita

  ?????????????????????????????????????????????????????????????????????????? ????????????????????????? * * * ?????????????????????????????????????DBMS??????????????????????????????DBMS????????????????????????????????????????????? 1. ???? ?????????????????????????????????????????????????????????????????????1?????? ???????????????? ?????????????????????????????DB???????OSS?PostgreSQL?????AP?????DB??????????????????? ???????? ?????10?????????????GB????????????????????????????DB?????????????????????????? ?????????????3,500?????????24????????????????????????????????????? ??AP?????????????????????????????????????????DB??PostgreSQL??????????????????PostgreSQL ????????????????????Vacuum????????????????????????????????????????????????????? ??????????????????PostgreSQL?OSS??????????????????????????????????????????????????DB MS??????Oracle Database 11gR2???????????????????????500GB???????????????????????????Partitioning ???????? Oracle Database Enterprise Edition?????????????????????????????????????????????? ????SAN?????Active/Standby???HA????????????????? 2. ????? 2.1. ???? PostgreSQL??????Oracle??????????????????????????????????????????????????????TEXT????? ????????????????????Oracle??????????????????????????PostgreSQL??csv???????Oracle Database?SQL*Loa der????????????? ??????????????????????????????DB??????????????Windows?Liunx??????????????????????? ????????????????????????????????????????????????? ?????????????PostgreSQL?NULL?????''????????????Oracle Database???????????????????????? ?????????? table { border-collapse: collapse; } th { border: solid 1px #666666; color: #000000; background-color: #ff9999; } td { border: solid 1px #666666; color: #000000; background-color: #ffffff; } ???? PostgreSQL Oracle Database ??? CHAR(n) CHAR(n),CLOB VARCHAR(n) VARCHAR2(n),CLOB TEXT CLOB ??? NUMERIC NUMBER INTEGER NUMBER SMALLINT NUMBER BIGINT NUMBER REAL NUMBER DOUBLE PRECISION NUMBER ??? DATE DATE TIMESTAMP TIMESTAMP ????? Bytea BLOB LOB BFILE/SecureFiles ??? OID ROWID 2.2. ????? ?????????????PostgreSQL?Oracle Database??????????SQL???????????????????????????????????Postg reSQL?LIMIT?OFFSET??Oracle Database?????????????????????? LIMIT,OFFSET???SELECT?????? /* PostgreSQL LIMIT,OFFSET */ SELECT ??? FROM ????? ORDER BY ???? LIMIT 2 OFFSET 5; /* Oracle Database????? */ SELECT ??? FROM (SELECT ???, ROWNUM line_no FROM (SELECT??? FROM ????? OREDR BY ???? ) ) WHERE line_no BETWEEN 6 AND 7; ??????????????????????????????????????????????????????????????????????????? ?????????????????? ????????????????????????????????????????????????Oracle Database??????????????????????Oracle Database????WHERE??????????????????????????????????????????????????????WHERE?????????????????????? 3. ???? ???????????????????????30%~40%????????????????????80%????????????????????? ?ITpro???:???????4????? ??????????????????????????????????? ·?????·??????????????????????????? ·????????????????????????????? ????????????????????????????????????????? 3.1. ??????? ????????????????????????????????????????·??????????????????????????????????? ???????????????????????????????????????????????????????·?????????????????? ???????????????????????????? (1)???????????????????? (2)???????????????????????????????????????????? (3)??????????????? (4)???????????????????????????????? ???????????·???????????????????????????????????????????????????????????????? ????????????????????? ????????·?? table { border-collapse: collapse; } th { border: solid 1px #666666; color: #000000; background-color: #ff9999; } td { border: solid 1px #666666; color: #000000; background-color: #ffffff; } ?? ?? ?? (1) ?????????? ????????????·???????????????????????? (2) ???????????????????? ?????????????????????????????? (3) ?????4????????????????? ???????????????????????DB????????? (4) ??????????(3)???????? ???????????????????????? ?????????????????????GB???????????????????????????????????????????(3)?????????? ??????? ??????????????????????????????????????????????csv??????????SQL*Loader?Oracle Database?????????????????????Oracle Database???????????????????????????INSERT????????????? ???????????????????????????????????????????????????????????????????????????? ?????????????????????? 3.2. ????? ???????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 3.3. ????? ??????????????????????????????????????????????????????????????????????????? ??????????????????????? DBMS????????????????????????SQL??????????????????????????????????????????????????PostgreSQL?Oracle Database???????????MVCC?????????????????????????Read Committed??????????????????????????????????????????????????????????????????????????????????? ????????????????DBMS?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 4. ??? PostgreSQL??Oracle Database?????????????????????????????? ????????????·????????????????????????????????????? ??????4???????????????????????·??????????????????? ???????????????????????????????????????????????? ?????????????????????????????????????????????DBMS???????????????????DBMS???????? ?????SQL?????????????????????????????DB???????????????????????????? ???????????????????????????DBMS?????????????????????????????????????????????????????? ??????????????????????????????

  Read the article

• Intermittent wired network issues in 14.04

  - by Tommy Brunn

  Since yesterday, my wired network connection has been dropping for a couple of seconds every 30 seconds or so. To my knowledge, I had not made any changes to my network. Output of ifconfig -a: ? ~ ifconfig -a eth0 Link encap:Ethernet HWaddr 6c:f0:49:b9:b1:7f inet addr:192.168.0.16 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::6ef0:49ff:feb9:b17f/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:11597 errors:0 dropped:0 overruns:0 frame:0 TX packets:9783 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:10101682 (10.1 MB) TX bytes:1215142 (1.2 MB) Interrupt:48 Base address:0x8000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:96691 errors:0 dropped:0 overruns:0 frame:0 TX packets:96691 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:13594355 (13.5 MB) TX bytes:13594355 (13.5 MB) lspci |grep Ethernet: 04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 03) Pinging my router: ? ~ ping 192.168.0.1 PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data. 64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=0.435 ms 64 bytes from 192.168.0.1: icmp_seq=2 ttl=64 time=0.571 ms ping: sendmsg: Network is unreachable ping: sendmsg: Network is unreachable ping: sendmsg: Network is unreachable ping: sendmsg: Network is unreachable ping: sendmsg: Network is unreachable 64 bytes from 192.168.0.1: icmp_seq=8 ttl=64 time=1.03 ms And the output of route: ? ~ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default 192.168.0.1 0.0.0.0 UG 0 0 0 eth0 192.168.0.0 * 255.255.255.0 U 1 0 0 eth0 Some messages from /var/logs/syslog: ? ~ tail -f /var/log/syslog Jun 6 10:37:34 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:37:34 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:37:37 lolbox dnsmasq[1138]: Maximum number of concurrent DNS queries reached (max: 150) Jun 6 10:37:37 lolbox dnsmasq[1362]: Maximum number of concurrent DNS queries reached (max: 150) Jun 6 10:37:39 lolbox dhclient: XMT: Solicit on eth0, interval 8660ms. Jun 6 10:37:39 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:37:39 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:37:47 lolbox dhclient: XMT: Solicit on eth0, interval 16820ms. Jun 6 10:37:47 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:37:47 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:38:04 lolbox dhclient: XMT: Solicit on eth0, interval 34410ms. Jun 6 10:38:04 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:38:04 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:38:16 lolbox NetworkManager[862]: <warn> (eth0): DHCPv6 request timed out. Jun 6 10:38:16 lolbox NetworkManager[862]: <info> (eth0): canceled DHCP transaction, DHCP client pid 13045 Jun 6 10:38:16 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 4 of 5 (IPv6 Configure Timeout) scheduled... Jun 6 10:38:16 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 4 of 5 (IPv6 Configure Timeout) started... Jun 6 10:38:16 lolbox NetworkManager[862]: <info> (eth0): device state change: activated -> failed (reason 'ip-config-unavailable') [100 120 5] Jun 6 10:38:16 lolbox NetworkManager[862]: <info> NetworkManager state is now DISCONNECTED Jun 6 10:38:16 lolbox NetworkManager[862]: <warn> Activation (eth0) failed for connection 'Wired connection 1' Jun 6 10:38:16 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 4 of 5 (IPv6 Configure Timeout) complete. Jun 6 10:38:16 lolbox NetworkManager[862]: <info> (eth0): device state change: failed -> disconnected (reason 'none') [120 30 0] Jun 6 10:38:16 lolbox NetworkManager[862]: <info> (eth0): deactivating device (reason 'none') [0] Jun 6 10:37:34 lolbox whoopsie[1133]: online Jun 6 10:38:16 lolbox whoopsie[1133]: offline Jun 6 10:38:16 lolbox dbus[485]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper) Jun 6 10:38:16 lolbox dbus[485]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher' Jun 6 10:38:16 lolbox NetworkManager[862]: <info> (eth0): canceled DHCP transaction, DHCP client pid 13044 Jun 6 10:38:16 lolbox NetworkManager[862]: <warn> DNS: plugin dnsmasq update failed Jun 6 10:38:16 lolbox NetworkManager[862]: <info> Removing DNS information from /sbin/resolvconf Jun 6 10:38:16 lolbox avahi-daemon[619]: Withdrawing address record for fe80::6ef0:49ff:feb9:b17f on eth0. Jun 6 10:38:16 lolbox avahi-daemon[619]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:38:16 lolbox avahi-daemon[619]: Interface eth0.IPv6 no longer relevant for mDNS. Jun 6 10:38:16 lolbox avahi-daemon[619]: Withdrawing address record for 192.168.0.16 on eth0. Jun 6 10:38:16 lolbox avahi-daemon[619]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.0.16. Jun 6 10:38:16 lolbox avahi-daemon[619]: Interface eth0.IPv4 no longer relevant for mDNS. Jun 6 10:38:16 lolbox dnsmasq[1362]: setting upstream servers from DBus Jun 6 10:38:17 lolbox avahi-daemon[619]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:38:17 lolbox avahi-daemon[619]: New relevant interface eth0.IPv6 for mDNS. Jun 6 10:38:17 lolbox avahi-daemon[619]: Registering new address record for fe80::6ef0:49ff:feb9:b17f on eth0.*. Jun 6 10:38:18 lolbox dnsmasq[1138]: no servers found in /var/run/dnsmasq/resolv.conf, will retry Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Auto-activating connection 'Wired connection 1'. Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) starting connection 'Wired connection 1' Jun 6 10:38:18 lolbox NetworkManager[862]: <info> (eth0): device state change: disconnected -> prepare (reason 'none') [30 40 0] Jun 6 10:38:18 lolbox NetworkManager[862]: <info> NetworkManager state is now CONNECTING Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) scheduled... Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) started... Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) scheduled... Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) complete. Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) starting... Jun 6 10:38:18 lolbox NetworkManager[862]: <info> (eth0): device state change: prepare -> config (reason 'none') [40 50 0] Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) successful. Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) scheduled. Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) complete. Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) started... Jun 6 10:38:18 lolbox NetworkManager[862]: <info> (eth0): device state change: config -> ip-config (reason 'none') [50 70 0] Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds) Jun 6 10:38:18 lolbox NetworkManager[862]: <info> dhclient started with pid 13160 Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Beginning DHCPv6 transaction (timeout in 45 seconds) Jun 6 10:38:18 lolbox NetworkManager[862]: <info> dhclient started with pid 13161 Jun 6 10:38:18 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) complete. Jun 6 10:38:18 lolbox avahi-daemon[619]: Withdrawing address record for fe80::6ef0:49ff:feb9:b17f on eth0. Jun 6 10:38:18 lolbox avahi-daemon[619]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:38:18 lolbox avahi-daemon[619]: Interface eth0.IPv6 no longer relevant for mDNS. Jun 6 10:38:18 lolbox dhclient: Internet Systems Consortium DHCP Client 4.2.4 Jun 6 10:38:18 lolbox dhclient: Copyright 2004-2012 Internet Systems Consortium. Jun 6 10:38:18 lolbox dhclient: All rights reserved. Jun 6 10:38:18 lolbox dhclient: For info, please visit https://www.isc.org/software/dhcp/ Jun 6 10:38:18 lolbox dhclient: Jun 6 10:38:19 lolbox dhclient: Internet Systems Consortium DHCP Client 4.2.4 Jun 6 10:38:19 lolbox dhclient: Copyright 2004-2012 Internet Systems Consortium. Jun 6 10:38:19 lolbox dhclient: All rights reserved. Jun 6 10:38:19 lolbox dhclient: For info, please visit https://www.isc.org/software/dhcp/ Jun 6 10:38:19 lolbox dhclient: Jun 6 10:38:19 lolbox NetworkManager[862]: <info> (eth0): DHCPv4 state changed nbi -> preinit Jun 6 10:38:19 lolbox dhclient: Bound to *:546 Jun 6 10:38:19 lolbox dhclient: Listening on Socket/eth0 Jun 6 10:38:19 lolbox dhclient: Sending on Socket/eth0 Jun 6 10:38:19 lolbox NetworkManager[862]: <info> (eth0): DHCPv6 state changed nbi -> preinit6 Jun 6 10:38:19 lolbox dhclient: Listening on LPF/eth0/6c:f0:49:b9:b1:7f Jun 6 10:38:19 lolbox dhclient: Sending on LPF/eth0/6c:f0:49:b9:b1:7f Jun 6 10:38:19 lolbox dhclient: Sending on Socket/fallback Jun 6 10:38:19 lolbox dhclient: DHCPREQUEST of 192.168.0.16 on eth0 to 255.255.255.255 port 67 (xid=0x3fc9376d) Jun 6 10:38:19 lolbox dhclient: XMT: Solicit on eth0, interval 1020ms. Jun 6 10:38:19 lolbox dhclient: send_packet6: Cannot assign requested address Jun 6 10:38:19 lolbox dhclient: dhc6: send_packet6() sent -1 of 77 bytes Jun 6 10:38:20 lolbox dhclient: DHCPACK of 192.168.0.16 from 192.168.0.1 Jun 6 10:38:20 lolbox dhclient: bound to 192.168.0.16 -- renewal in 41481 seconds. Jun 6 10:38:20 lolbox NetworkManager[862]: <info> (eth0): DHCPv4 state changed preinit -> reboot Jun 6 10:38:20 lolbox NetworkManager[862]: <info> address 192.168.0.16 Jun 6 10:38:20 lolbox NetworkManager[862]: <info> prefix 24 (255.255.255.0) Jun 6 10:38:20 lolbox NetworkManager[862]: <info> gateway 192.168.0.1 Jun 6 10:38:20 lolbox NetworkManager[862]: <info> nameserver '83.255.245.11' Jun 6 10:38:20 lolbox NetworkManager[862]: <info> nameserver '193.150.193.150' Jun 6 10:38:20 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Configure Commit) scheduled... Jun 6 10:38:20 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Commit) started... Jun 6 10:38:20 lolbox avahi-daemon[619]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.0.16. Jun 6 10:38:20 lolbox avahi-daemon[619]: New relevant interface eth0.IPv4 for mDNS. Jun 6 10:38:20 lolbox avahi-daemon[619]: Registering new address record for 192.168.0.16 on eth0.IPv4. Jun 6 10:38:20 lolbox dhclient: XMT: Solicit on eth0, interval 2110ms. Jun 6 10:38:20 lolbox dhclient: send_packet6: Cannot assign requested address Jun 6 10:38:20 lolbox dhclient: dhc6: send_packet6() sent -1 of 77 bytes Jun 6 10:38:20 lolbox avahi-daemon[619]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:38:20 lolbox avahi-daemon[619]: New relevant interface eth0.IPv6 for mDNS. Jun 6 10:38:20 lolbox avahi-daemon[619]: Registering new address record for fe80::6ef0:49ff:feb9:b17f on eth0.*. Jun 6 10:38:21 lolbox NetworkManager[862]: <info> (eth0): device state change: ip-config -> secondaries (reason 'none') [70 90 0] Jun 6 10:38:21 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Commit) complete. Jun 6 10:38:21 lolbox NetworkManager[862]: <info> (eth0): device state change: secondaries -> activated (reason 'none') [90 100 0] Jun 6 10:38:21 lolbox NetworkManager[862]: <info> NetworkManager state is now CONNECTED_GLOBAL Jun 6 10:38:21 lolbox NetworkManager[862]: <info> Policy set 'Wired connection 1' (eth0) as default for IPv4 routing and DNS. Jun 6 10:38:21 lolbox NetworkManager[862]: <info> Writing DNS information to /sbin/resolvconf Jun 6 10:38:21 lolbox dnsmasq[1362]: setting upstream servers from DBus Jun 6 10:38:21 lolbox dnsmasq[1362]: using nameserver 127.0.0.1#53 Jun 6 10:38:21 lolbox dnsmasq[1362]: using nameserver 193.150.193.150#53 Jun 6 10:38:21 lolbox dnsmasq[1362]: using nameserver 83.255.245.11#53 Jun 6 10:38:21 lolbox NetworkManager[862]: <info> Activation (eth0) successful, device activated. Jun 6 10:38:21 lolbox whoopsie[1133]: message repeated 2 times: [ offline] Jun 6 10:38:21 lolbox whoopsie[1133]: online Jun 6 10:38:21 lolbox ntpdate[13217]: Can't find host ntp.ubuntu.com: Name or service not known (-2) Jun 6 10:38:21 lolbox ntpdate[13217]: no servers can be used, exiting Jun 6 10:38:22 lolbox dnsmasq[1138]: reading /var/run/dnsmasq/resolv.conf Jun 6 10:38:22 lolbox dnsmasq[1138]: using nameserver 127.0.1.1#53 Jun 6 10:38:22 lolbox dhclient: XMT: Solicit on eth0, interval 4080ms. Jun 6 10:38:22 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:38:22 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:38:26 lolbox dhclient: XMT: Solicit on eth0, interval 8450ms. Jun 6 10:38:26 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:38:26 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:38:35 lolbox dhclient: XMT: Solicit on eth0, interval 16630ms. Jun 6 10:38:35 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:38:35 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:38:51 lolbox dhclient: XMT: Solicit on eth0, interval 34860ms. Jun 6 10:38:51 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:38:51 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:38:58 lolbox dnsmasq[1138]: Maximum number of concurrent DNS queries reached (max: 150) Jun 6 10:38:58 lolbox dnsmasq[1362]: Maximum number of concurrent DNS queries reached (max: 150) Jun 6 10:39:04 lolbox NetworkManager[862]: <warn> (eth0): DHCPv6 request timed out. Jun 6 10:39:04 lolbox NetworkManager[862]: <info> (eth0): canceled DHCP transaction, DHCP client pid 13161 Jun 6 10:39:04 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 4 of 5 (IPv6 Configure Timeout) scheduled... Jun 6 10:39:04 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 4 of 5 (IPv6 Configure Timeout) started... Jun 6 10:39:04 lolbox NetworkManager[862]: <info> (eth0): device state change: activated -> failed (reason 'ip-config-unavailable') [100 120 5] Jun 6 10:39:04 lolbox NetworkManager[862]: <info> NetworkManager state is now DISCONNECTED Jun 6 10:39:04 lolbox NetworkManager[862]: <warn> Activation (eth0) failed for connection 'Wired connection 1' Jun 6 10:38:22 lolbox whoopsie[1133]: online Jun 6 10:39:04 lolbox whoopsie[1133]: offline Jun 6 10:39:04 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 4 of 5 (IPv6 Configure Timeout) complete. Jun 6 10:39:04 lolbox dbus[485]: [system] Activating service name='org.freedesktop.nm_dispatcher' (using servicehelper) Jun 6 10:39:04 lolbox NetworkManager[862]: <info> (eth0): device state change: failed -> disconnected (reason 'none') [120 30 0] Jun 6 10:39:04 lolbox NetworkManager[862]: <info> (eth0): deactivating device (reason 'none') [0] Jun 6 10:39:04 lolbox dbus[485]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher' Jun 6 10:39:04 lolbox NetworkManager[862]: <info> (eth0): canceled DHCP transaction, DHCP client pid 13160 Jun 6 10:39:04 lolbox avahi-daemon[619]: Withdrawing address record for fe80::6ef0:49ff:feb9:b17f on eth0. Jun 6 10:39:04 lolbox avahi-daemon[619]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:39:04 lolbox avahi-daemon[619]: Interface eth0.IPv6 no longer relevant for mDNS. Jun 6 10:39:04 lolbox avahi-daemon[619]: Withdrawing address record for 192.168.0.16 on eth0. Jun 6 10:39:04 lolbox avahi-daemon[619]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.0.16. Jun 6 10:39:04 lolbox avahi-daemon[619]: Interface eth0.IPv4 no longer relevant for mDNS. Jun 6 10:39:04 lolbox NetworkManager[862]: <warn> DNS: plugin dnsmasq update failed Jun 6 10:39:04 lolbox NetworkManager[862]: <info> Removing DNS information from /sbin/resolvconf Jun 6 10:39:04 lolbox dnsmasq[1362]: setting upstream servers from DBus Jun 6 10:39:05 lolbox avahi-daemon[619]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:39:05 lolbox avahi-daemon[619]: New relevant interface eth0.IPv6 for mDNS. Jun 6 10:39:05 lolbox avahi-daemon[619]: Registering new address record for fe80::6ef0:49ff:feb9:b17f on eth0.*. Jun 6 10:39:06 lolbox dnsmasq[1138]: no servers found in /var/run/dnsmasq/resolv.conf, will retry Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Auto-activating connection 'Wired connection 1'. Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) starting connection 'Wired connection 1' Jun 6 10:39:07 lolbox NetworkManager[862]: <info> (eth0): device state change: disconnected -> prepare (reason 'none') [30 40 0] Jun 6 10:39:07 lolbox NetworkManager[862]: <info> NetworkManager state is now CONNECTING Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) scheduled... Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) started... Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) scheduled... Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 1 of 5 (Device Prepare) complete. Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) starting... Jun 6 10:39:07 lolbox NetworkManager[862]: <info> (eth0): device state change: prepare -> config (reason 'none') [40 50 0] Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) successful. Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) scheduled. Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 2 of 5 (Device Configure) complete. Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) started... Jun 6 10:39:07 lolbox NetworkManager[862]: <info> (eth0): device state change: config -> ip-config (reason 'none') [50 70 0] Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds) Jun 6 10:39:07 lolbox NetworkManager[862]: <info> dhclient started with pid 13270 Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Beginning DHCPv6 transaction (timeout in 45 seconds) Jun 6 10:39:07 lolbox NetworkManager[862]: <info> dhclient started with pid 13271 Jun 6 10:39:07 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 3 of 5 (IP Configure Start) complete. Jun 6 10:39:07 lolbox avahi-daemon[619]: Withdrawing address record for fe80::6ef0:49ff:feb9:b17f on eth0. Jun 6 10:39:07 lolbox avahi-daemon[619]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:39:07 lolbox avahi-daemon[619]: Interface eth0.IPv6 no longer relevant for mDNS. Jun 6 10:39:07 lolbox dhclient: Internet Systems Consortium DHCP Client 4.2.4 Jun 6 10:39:07 lolbox dhclient: Copyright 2004-2012 Internet Systems Consortium. Jun 6 10:39:07 lolbox dhclient: All rights reserved. Jun 6 10:39:07 lolbox dhclient: For info, please visit https://www.isc.org/software/dhcp/ Jun 6 10:39:07 lolbox dhclient: Jun 6 10:39:08 lolbox dhclient: Internet Systems Consortium DHCP Client 4.2.4 Jun 6 10:39:08 lolbox dhclient: Copyright 2004-2012 Internet Systems Consortium. Jun 6 10:39:08 lolbox dhclient: All rights reserved. Jun 6 10:39:08 lolbox dhclient: For info, please visit https://www.isc.org/software/dhcp/ Jun 6 10:39:08 lolbox dhclient: Jun 6 10:39:08 lolbox dhclient: Bound to *:546 Jun 6 10:39:08 lolbox dhclient: Listening on Socket/eth0 Jun 6 10:39:08 lolbox dhclient: Sending on Socket/eth0 Jun 6 10:39:08 lolbox kernel: [ 1446.098590] type=1400 audit(1402043948.002:75): apparmor="DENIED" operation="signal" profile="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=13273 comm="nm-dhcp-client." requested_mask="send" denied_mask="send" signal=term peer="/sbin/dhclient" Jun 6 10:39:08 lolbox kernel: [ 1446.098599] type=1400 audit(1402043948.002:76): apparmor="DENIED" operation="signal" profile="/sbin/dhclient" pid=13273 comm="nm-dhcp-client." requested_mask="receive" denied_mask="receive" signal=term peer="/usr/lib/NetworkManager/nm-dhcp-client.action" Jun 6 10:39:08 lolbox NetworkManager[862]: <info> (eth0): DHCPv4 state changed nbi -> preinit Jun 6 10:39:08 lolbox dhclient: Listening on LPF/eth0/6c:f0:49:b9:b1:7f Jun 6 10:39:08 lolbox dhclient: Sending on LPF/eth0/6c:f0:49:b9:b1:7f Jun 6 10:39:08 lolbox dhclient: Sending on Socket/fallback Jun 6 10:39:08 lolbox dhclient: DHCPREQUEST of 192.168.0.16 on eth0 to 255.255.255.255 port 67 (xid=0x3e0183b9) Jun 6 10:39:08 lolbox dhclient: XMT: Solicit on eth0, interval 1050ms. Jun 6 10:39:08 lolbox dhclient: send_packet6: Cannot assign requested address Jun 6 10:39:08 lolbox dhclient: dhc6: send_packet6() sent -1 of 77 bytes Jun 6 10:39:09 lolbox dhclient: DHCPACK of 192.168.0.16 from 192.168.0.1 Jun 6 10:39:09 lolbox dhclient: bound to 192.168.0.16 -- renewal in 35498 seconds. Jun 6 10:39:09 lolbox NetworkManager[862]: <info> (eth0): DHCPv4 state changed preinit -> reboot Jun 6 10:39:09 lolbox NetworkManager[862]: <info> address 192.168.0.16 Jun 6 10:39:09 lolbox NetworkManager[862]: <info> prefix 24 (255.255.255.0) Jun 6 10:39:09 lolbox NetworkManager[862]: <info> gateway 192.168.0.1 Jun 6 10:39:09 lolbox NetworkManager[862]: <info> nameserver '83.255.245.11' Jun 6 10:39:09 lolbox NetworkManager[862]: <info> nameserver '193.150.193.150' Jun 6 10:39:09 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Configure Commit) scheduled... Jun 6 10:39:09 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Commit) started... Jun 6 10:39:09 lolbox avahi-daemon[619]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.0.16. Jun 6 10:39:09 lolbox avahi-daemon[619]: New relevant interface eth0.IPv4 for mDNS. Jun 6 10:39:09 lolbox avahi-daemon[619]: Registering new address record for 192.168.0.16 on eth0.IPv4. Jun 6 10:39:09 lolbox avahi-daemon[619]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::6ef0:49ff:feb9:b17f. Jun 6 10:39:09 lolbox avahi-daemon[619]: New relevant interface eth0.IPv6 for mDNS. Jun 6 10:39:09 lolbox avahi-daemon[619]: Registering new address record for fe80::6ef0:49ff:feb9:b17f on eth0.*. Jun 6 10:39:10 lolbox dhclient: XMT: Solicit on eth0, interval 2180ms. Jun 6 10:39:10 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:39:10 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:39:10 lolbox NetworkManager[862]: <info> (eth0): device state change: ip-config -> secondaries (reason 'none') [70 90 0] Jun 6 10:39:10 lolbox NetworkManager[862]: <info> Activation (eth0) Stage 5 of 5 (IPv4 Commit) complete. Jun 6 10:39:10 lolbox NetworkManager[862]: <info> (eth0): device state change: secondaries -> activated (reason 'none') [90 100 0] Jun 6 10:39:10 lolbox NetworkManager[862]: <info> NetworkManager state is now CONNECTED_GLOBAL Jun 6 10:39:10 lolbox NetworkManager[862]: <info> Policy set 'Wired connection 1' (eth0) as default for IPv4 routing and DNS. Jun 6 10:39:10 lolbox NetworkManager[862]: <info> Writing DNS information to /sbin/resolvconf Jun 6 10:39:10 lolbox dnsmasq[1362]: setting upstream servers from DBus Jun 6 10:39:10 lolbox dnsmasq[1362]: using nameserver 127.0.0.1#53 Jun 6 10:39:10 lolbox dnsmasq[1362]: using nameserver 193.150.193.150#53 Jun 6 10:39:10 lolbox dnsmasq[1362]: using nameserver 83.255.245.11#53 Jun 6 10:39:10 lolbox NetworkManager[862]: <info> Activation (eth0) successful, device activated. Jun 6 10:39:10 lolbox whoopsie[1133]: message repeated 2 times: [ offline] Jun 6 10:39:10 lolbox whoopsie[1133]: online Jun 6 10:39:10 lolbox ntpdate[13339]: Can't find host ntp.ubuntu.com: Name or service not known (-2) Jun 6 10:39:10 lolbox ntpdate[13339]: no servers can be used, exiting Jun 6 10:39:11 lolbox dnsmasq[1138]: reading /var/run/dnsmasq/resolv.conf Jun 6 10:39:11 lolbox dnsmasq[1138]: using nameserver 127.0.1.1#53 Jun 6 10:39:12 lolbox dhclient: XMT: Solicit on eth0, interval 4350ms. Jun 6 10:39:12 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:39:12 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:39:16 lolbox dhclient: XMT: Solicit on eth0, interval 8740ms. Jun 6 10:39:16 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:39:16 lolbox dhclient: IA_NA status code NoAddrsAvail. Jun 6 10:39:17 lolbox dnsmasq[1138]: Maximum number of concurrent DNS queries reached (max: 150) Jun 6 10:39:17 lolbox dnsmasq[1362]: Maximum number of concurrent DNS queries reached (max: 150) Jun 6 10:39:25 lolbox dhclient: XMT: Solicit on eth0, interval 17610ms. Jun 6 10:39:25 lolbox dhclient: RCV: Advertise message on eth0 from fe80::120d:7fff:fe97:9d54. Jun 6 10:39:25 lolbox dhclient: IA_NA status code NoAddrsAvail.

  Read the article

• jQuery: How do I insert an html string an arbitrary number of times (i.e. not with an each() function)?

  - by Sam Bivins

  I just need to take a certain html query object and append it to an html element a lot of times. I have this: var box = $("<div class='box'>&nbsp</div>"); $("#firstbox").after(box); and it works fine, but it just adds one 'box' after the #firstbox element. I'd like to do something like this: var box = $("<div class='box'>&nbsp</div>"); $("#firstbox").after(box * 6000); so that it will insert 6000 copies of that 'box' html, but this is not working. This is I'm sure the easiest thing to do, but I can't seem to find how to multiply actions like this without using the each() function, which doesn't apply here because I don't have 6000 of anything on my page. Thanks.

  Read the article

• Sorting Algorithms

  - by MarkPearl

  General Every time I go back to university I find myself wading through sorting algorithms and their implementation in C++. Up to now I haven’t really appreciated their true value. However as I discovered this last week with Dictionaries in C# – having a knowledge of some basic programming principles can greatly improve the performance of a system and make one think twice about how to tackle a problem. I’m going to cover briefly in this post the following: Selection Sort Insertion Sort Shellsort Quicksort Mergesort Heapsort (not complete) Selection Sort Array based selection sort is a simple approach to sorting an unsorted array. Simply put, it repeats two basic steps to achieve a sorted collection. It starts with a collection of data and repeatedly parses it, each time sorting out one element and reducing the size of the next iteration of parsed data by one. So the first iteration would go something like this… Go through the entire array of data and find the lowest value Place the value at the front of the array The second iteration would go something like this… Go through the array from position two (position one has already been sorted with the smallest value) and find the next lowest value in the array. Place the value at the second position in the array This process would be completed until the entire array had been sorted. A positive about selection sort is that it does not make many item movements. In fact, in a worst case scenario every items is only moved once. Selection sort is however a comparison intensive sort. If you had 10 items in a collection, just to parse the collection you would have 10+9+8+7+6+5+4+3+2=54 comparisons to sort regardless of how sorted the collection was to start with. If you think about it, if you applied selection sort to a collection already sorted, you would still perform relatively the same number of iterations as if it was not sorted at all. Many of the following algorithms try and reduce the number of comparisons if the list is already sorted – leaving one with a best case and worst case scenario for comparisons. Likewise different approaches have different levels of item movement. Depending on what is more expensive, one may give priority to one approach compared to another based on what is more expensive, a comparison or a item move. Insertion Sort Insertion sort tries to reduce the number of key comparisons it performs compared to selection sort by not “doing anything” if things are sorted. Assume you had an collection of numbers in the following order… 10 18 25 30 23 17 45 35 There are 8 elements in the list. If we were to start at the front of the list – 10 18 25 & 30 are already sorted. Element 5 (23) however is smaller than element 4 (30) and so needs to be repositioned. We do this by copying the value at element 5 to a temporary holder, and then begin shifting the elements before it up one. So… Element 5 would be copied to a temporary holder 10 18 25 30 23 17 45 35 – T 23 Element 4 would shift to Element 5 10 18 25 30 30 17 45 35 – T 23 Element 3 would shift to Element 4 10 18 25 25 30 17 45 35 – T 23 Element 2 (18) is smaller than the temporary holder so we put the temporary holder value into Element 3. 10 18 23 25 30 17 45 35 – T 23   We now have a sorted list up to element 6. And so we would repeat the same process by moving element 6 to a temporary value and then shifting everything up by one from element 2 to element 5. As you can see, one major setback for this technique is the shifting values up one – this is because up to now we have been considering the collection to be an array. If however the collection was a linked list, we would not need to shift values up, but merely remove the link from the unsorted value and “reinsert” it in a sorted position. Which would reduce the number of transactions performed on the collection. So.. Insertion sort seems to perform better than selection sort – however an implementation is slightly more complicated. This is typical with most sorting algorithms – generally, greater performance leads to greater complexity. Also, insertion sort performs better if a collection of data is already sorted. If for instance you were handed a sorted collection of size n, then only n number of comparisons would need to be performed to verify that it is sorted. It’s important to note that insertion sort (array based) performs a number item moves – every time an item is “out of place” several items before it get shifted up. Shellsort – Diminishing Increment Sort So up to now we have covered Selection Sort & Insertion Sort. Selection Sort makes many comparisons and insertion sort (with an array) has the potential of making many item movements. Shellsort is an approach that takes the normal insertion sort and tries to reduce the number of item movements. In Shellsort, elements in a collection are viewed as sub-collections of a particular size. Each sub-collection is sorted so that the elements that are far apart move closer to their final position. Suppose we had a collection of 15 elements… 10 20 15 45 36 48 7 60 18 50 2 19 43 30 55 First we may view the collection as 7 sub-collections and sort each sublist, lets say at intervals of 7 10 60 55 – 20 18 – 15 50 – 45 2 – 36 19 – 48 43 – 7 30 10 55 60 – 18 20 – 15 50 – 2 45 – 19 36 – 43 48 – 7 30 (Sorted) We then sort each sublist at a smaller inter – lets say 4 10 55 60 18 – 20 15 50 2 – 45 19 36 43 – 48 7 30 10 18 55 60 – 2 15 20 50 – 19 36 43 45 – 7 30 48 (Sorted) We then sort elements at a distance of 1 (i.e. we apply a normal insertion sort) 10 18 55 60 2 15 20 50 19 36 43 45 7 30 48 2 7 10 15 18 19 20 30 36 43 45 48 50 55 (Sorted) The important thing with shellsort is deciding on the increment sequence of each sub-collection. From what I can tell, there isn’t any definitive method and depending on the order of your elements, different increment sequences may perform better than others. There are however certain increment sequences that you may want to avoid. An even based increment sequence (e.g. 2 4 8 16 32 …) should typically be avoided because it does not allow for even elements to be compared with odd elements until the final sort phase – which in a way would negate many of the benefits of using sub-collections. The performance on the number of comparisons and item movements of Shellsort is hard to determine, however it is considered to be considerably better than the normal insertion sort. Quicksort Quicksort uses a divide and conquer approach to sort a collection of items. The collection is divided into two sub-collections – and the two sub-collections are sorted and combined into one list in such a way that the combined list is sorted. The algorithm is in general pseudo code below… Divide the collection into two sub-collections Quicksort the lower sub-collection Quicksort the upper sub-collection Combine the lower & upper sub-collection together As hinted at above, quicksort uses recursion in its implementation. The real trick with quicksort is to get the lower and upper sub-collections to be of equal size. The size of a sub-collection is determined by what value the pivot is. Once a pivot is determined, one would partition to sub-collections and then repeat the process on each sub collection until you reach the base case. With quicksort, the work is done when dividing the sub-collections into lower & upper collections. The actual combining of the lower & upper sub-collections at the end is relatively simple since every element in the lower sub-collection is smaller than the smallest element in the upper sub-collection. Mergesort With quicksort, the average-case complexity was O(nlog2n) however the worst case complexity was still O(N*N). Mergesort improves on quicksort by always having a complexity of O(nlog2n) regardless of the best or worst case. So how does it do this? Mergesort makes use of the divide and conquer approach to partition a collection into two sub-collections. It then sorts each sub-collection and combines the sorted sub-collections into one sorted collection. The general algorithm for mergesort is as follows… Divide the collection into two sub-collections Mergesort the first sub-collection Mergesort the second sub-collection Merge the first sub-collection and the second sub-collection As you can see.. it still pretty much looks like quicksort – so lets see where it differs… Firstly, mergesort differs from quicksort in how it partitions the sub-collections. Instead of having a pivot – merge sort partitions each sub-collection based on size so that the first and second sub-collection of relatively the same size. This dividing keeps getting repeated until the sub-collections are the size of a single element. If a sub-collection is one element in size – it is now sorted! So the trick is how do we put all these sub-collections together so that they maintain their sorted order. Sorted sub-collections are merged into a sorted collection by comparing the elements of the sub-collection and then adjusting the sorted collection. Lets have a look at a few examples… Assume 2 sub-collections with 1 element each 10 & 20 Compare the first element of the first sub-collection with the first element of the second sub-collection. Take the smallest of the two and place it as the first element in the sorted collection. In this scenario 10 is smaller than 20 so 10 is taken from sub-collection 1 leaving that sub-collection empty, which means by default the next smallest element is in sub-collection 2 (20). So the sorted collection would be 10 20 Lets assume 2 sub-collections with 2 elements each 10 20 & 15 19 So… again we would Compare 10 with 15 – 10 is the winner so we add it to our sorted collection (10) leaving us with 20 & 15 19 Compare 20 with 15 – 15 is the winner so we add it to our sorted collection (10 15) leaving us with 20 & 19 Compare 20 with 19 – 19 is the winner so we add it to our sorted collection (10 15 19) leaving us with 20 & _ 20 is by default the winner so our sorted collection is 10 15 19 20. Make sense? Heapsort (still needs to be completed) So by now I am tired of sorting algorithms and trying to remember why they were so important. I think every year I go through this stuff I wonder to myself why are we made to learn about selection sort and insertion sort if they are so bad – why didn’t we just skip to Mergesort & Quicksort. I guess the only explanation I have for this is that sometimes you learn things so that you can implement them in future – and other times you learn things so that you know it isn’t the best way of implementing things and that you don’t need to implement it in future. Anyhow… luckily this is going to be the last one of my sorts for today. The first step in heapsort is to convert a collection of data into a heap. After the data is converted into a heap, sorting begins… So what is the definition of a heap? If we have to convert a collection of data into a heap, how do we know when it is a heap and when it is not? The definition of a heap is as follows: A heap is a list in which each element contains a key, such that the key in the element at position k in the list is at least as large as the key in the element at position 2k +1 (if it exists) and 2k + 2 (if it exists). Does that make sense? At first glance I’m thinking what the heck??? But then after re-reading my notes I see that we are doing something different – up to now we have really looked at data as an array or sequential collection of data that we need to sort – a heap represents data in a slightly different way – although the data is stored in a sequential collection, for a sequential collection of data to be in a valid heap – it is “semi sorted”. Let me try and explain a bit further with an example… Example 1 of Potential Heap Data Assume we had a collection of numbers as follows 1[1] 2[2] 3[3] 4[4] 5[5] 6[6] For this to be a valid heap element with value of 1 at position [1] needs to be greater or equal to the element at position [3] (2k +1) and position [4] (2k +2). So in the above example, the collection of numbers is not in a valid heap. Example 2 of Potential Heap Data Lets look at another collection of numbers as follows 6[1] 5[2] 4[3] 3[4] 2[5] 1[6] Is this a valid heap? Well… element with the value 6 at position 1 must be greater or equal to the element at position [3] and position [4]. Is 6 > 4 and 6 > 3? Yes it is. Lets look at element 5 as position 2. It must be greater than the values at [4] & [5]. Is 5 > 3 and 5 > 2? Yes it is. If you continued to examine this second collection of data you would find that it is in a valid heap based on the definition of a heap.

  Read the article

< Previous Page | 166 167 168 169 170 171 172 173 174 175 176 177  | Next Page >