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  • return the result of a query and the total number of rows in a single function

    - by csotelo
    This is a question as might be focused on working in the best way, if there are other alternatives or is the only way: Using Codeigniter ... I have the typical 2 functions of list records and show total number of records (using the page as an alternative). The problem is that they are rather large. Sample 2 functions in my model: count Rows: function get_all_count() { $this->db->select('u.id_user'); $this->db->from('user u'); if($this->session->userdata('detail') != '1') { $this->db->join('management m', 'm.id_user = u.id_user', 'inner'); $this->db->where('id_detail', $this->session->userdata('detail')); if($this->session->userdata('management') === '1') { $this->db->or_where('detail', 1); } else { $this->db->where("id_profile IN ( SELECT e2.id_profile FROM profile e, profile e2, profile_path p, profile_path p2 WHERE e.id_profile = " . $this->session->userdata('profile') . " AND p2.id_profile = e.id_profile AND p.path LIKE(CONCAT(p2.path,'%')) AND e2.id_profile = p.id_profile )", NULL, FALSE); $this->db->where('MD5(u.id_user) <>', $this->session->userdata('id_user')); } } $this->db->where('u.id_user <>', 1); $this->db->where('flag <>', 3); $query = $this->db->get(); return $query->num_rows(); } results per page function get_all($limit, $offset, $sort = '') { $this->db->select('u.id_user, user, email, flag'); $this->db->from('user u'); if($this->session->userdata('detail') != '1') { $this->db->join('management m', 'm.id_user = u.id_user', 'inner'); $this->db->where('id_detail', $this->session->userdata('detail')); if($this->session->userdata('management') === '1') { $this->db->or_where('detail', 1); } else { $this->db->where("id_profile IN ( SELECT e2.id_profile FROM profile e, profile e2, profile_path p, profile_path p2 WHERE e.id_profile = " . $this->session->userdata('profile') . " AND p2.id_profile = e.id_profile AND p.path LIKE(CONCAT(p2.path,'%')) AND e2.id_profile = p.id_profile )", NULL, FALSE); $this->db->where('MD5(u.id_user) <>', $this->session->userdata('id_user')); } } $this->db->where('u.id_user <>', 1); $this->db->where('flag <>', 3); if($sort) $this->db->order_by($sort); $this->db->limit($limit, $offset); $query = $this->db->get(); return $query->result(); } You see, I repeat the most of the functions, the difference is that only the number of fields and management pages. I wonder if there is any alternative to get as much results as the query in a single function. I have seen many tutorials, and all create 2 functions: one to count and another to show results ... Will there be more optimal?

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  • What amount of PHP memory usage is reasonable for multiple WordPress sites? [closed]

    - by John
    It seems like I've been plagued with memory usage issues most of the time I've been blogging (7 years). I upgraded my hosting to a HostGator VPS and still seem to have issues. I have about a dozen WP 3.4.2 sites running within a single account. Each has a separate installation. I finally installed TPC! Memory Usage within one of my WP installs to see what was going on. The memory usage just standing still is on the order of 40 MB. This seems high, but I don't know. What would be a reasonable memory usage for these WP installs? Do I need to take other things into account, or am I even looking at it the right way?

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  • How do I swap two objects in a GC language without triggering GC?

    - by TenFour04
    I have two array lists. that I want to swap each frame. My question is, does the variable 'temp' need to be a member variable to avoid triggering GC, assuming this method is called on dozens of objects each frame? I'm not creating a new object, just a new reference to an object. public void LateUpdate(){ ArrayList<int> temp = previousFrameCollisions; previousFrameCollisions = currentFrameCollisions; currentFrameCollisions = temp; currentFrameCollisions.clear(); } I've been told there's no reason to make a primitive into a member variable just to avoid GC, so my best guess is that this also applies to object references.

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  • Improving python code

    - by cobie
    I just answered the question on project euler about finding circular primes below 1 million using python. My solution is below. I was able to reduce the running time of the solution from 9 seconds to about 3 seconds. I would like to see what else can be done to the code to reduce its running time further. This is strictly for educational purposes and for fun. import math import time def getPrimes(n): """returns set of all primes below n""" non_primes = [j for j in range(4, n, 2)] # 2 covers all even numbers for i in range(3, n, 2): non_primes.extend([j for j in range(i*2, n, i)]) return set([i for i in range(2, n)]) - set(non_primes) def getCircularPrimes(n): primes = getPrimes(n) is_circ = [] for prime in primes: prime_str = str(prime) iter_count = len(prime_str) - 1 rotated_num = [] while iter_count > 0: prime_str = prime_str[1:] + prime_str[:1] rotated_num.append(int(prime_str)) iter_count -= 1 if primes >= set(rotated_num): is_circ.append(prime) return len(is_circ)

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  • How do I swap two objects in C# (specifically Mono) without triggering GC?

    - by TenFour04
    I have two array lists. that I want to swap each frame. My question is, does the variable 'temp' need to be a member variable to avoid triggering GC, assuming this method is called on dozens of objects each frame? I'm not creating a new object, just a new reference to an object. public void LateUpdate(){ ArrayList<int> temp = previousFrameCollisions; previousFrameCollisions = currentFrameCollisions; currentFrameCollisions = temp; currentFrameCollisions.clear(); } I've been told there's no reason to make a primitive into a member variable just to avoid GC, so my best guess is that this also applies to object references.

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  • How can you identify duplicate CSS rules?

    - by DanMan
    I'm not talking about used/unused here. I have two stylesheets and some rules differ (either in selectors, rules or both) and some are exactly the same. So I'm looking for a way to extract and move those rules, which are the same in both files, into a third stylesheet. In other words: an intersection of two stylesheets. Strangely, I couldn't find a software for this. Would have expected this to be a more common problem. Background, for those who care: I'm converting a desktop website into a mobile one and I've started by duplicating the desktop stylesheet and changing it (throwing stuff out, adding to it).

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  • Minimizing use of paper

    - by Abody97
    I've recently faced this problem in a dynamic programming curriculum, and I honestly have no idea about how to determine the appropriate state. You're given N (1 <= N <= 70) paragraphs and M (1 <= M <= N) figures. Each paragraph i requires PL_i (1 <= PL_i <= 100) lines and references at most one figure. Each figure is referenced exactly once (i.e., no two paragraphs can reference the same figure, and for each figure there's a paragraph that references it.) Each figure requires PF_i (1 <= PF_i <= 100) lines. The task is to distribute those figures and paragraphs on paper in the order they're given, where one paper fits for L lines at most. No paragraph or figure is too large to fit on one paper. If a paragraph x placed on paper x_p references a figure y then y must be placed on either the paper x_p - 1 or x_p or x_p + 1. We have to find the minimum number of lines (and thus pages) to allocate in order to distribute all the figures and paragraphs. Any help would be extremely appreciated. Thanks in advance!

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  • Where can I get the 10k common English dictionary words which Stack overflow uses in related question? [migrated]

    - by itpian.com
    Where can I get the 10k common English dictionary words which Stack overflow uses in related question? Here in SE podcast - http://blog.stackoverflow.com/2008/12/podcast-32/ One of our major performance optimizations for the “related questions” query is removing the top 10,000 most common English dictionary words (as determined by Google search) before submitting the query to the SQL Server 2008 full text engine. It’s shocking how little is left of most posts once you remove the top 10k English dictionary words. This helps limit and narrow the returned results, which makes the query dramatically faster.

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  • linux hardware raid 10 / lvm / virtual machine partition alignment and filesystem optimization

    - by Jason Ward
    I've been reading everything I can find about partition alignment and filesystem optimization (ext4 and xfs) but still don't know enough to be confident in setting up my current configuration. My remaining confusion comes from the LVM layer and if I should use raid parameters on the filesystem in guest os'es. My main questions are: When I use 'pvcreate --dataalignment' do I use the stripe-width as calculated for a filesystem on RAID (128kB for ext4 in my situation), the Stripe size of the RAID set (256kB), something else altogether, or do I not need this? When I create ext2/3/4 or xfs filesystems in guests on the Logical Volumes, should I add the settings for the underlying RAID (e.g. mkfs.ext4 -b 4096 -E stride=64,stripe-width=128)? Does anyone see any glaring errors in my set up below? I'm running some benchmarks now but haven't done enough to start comparing results. I have four drives in RAID 10 on a 3ware 9750-4i controller (more details on the settings below) giving me a 6.0TB device at /dev/sda. Here is my partition table: Model: LSI 9750-4i DISK (scsi) Disk /dev/sda: 5722024MiB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1.00MiB 257MiB 256MiB ext4 BOOTPART boot 2 257MiB 4353MiB 4096MiB linux-swap(v1) 3 4353MiB 266497MiB 262144MiB ext4 4 266497MiB 4460801MiB 4194304MiB Partition 1 is to be the /boot partition for my xen host. Partition 2 is swap. Partition 3 is to be the root (/) for my xen host. Partition 4 is to be (the only) physical volume to be used by LVM (for those who are counting, I left about 1.2TB unallocated for now) For my Xen guests, I usually create a Logical Volume of the needed size and present it to the guests for them to partition as needed. I know there are other ways of handling that but this method works best for my situation. Here's the hardware of interest on my CentOS 6.3 Xen Host: 4x Seagate Barracuda 3TB ST3000DM001 Drives (sector size: 512 logical/4096 physical) 3ware 9750-4i w/BBU (sector size reported: 512 logical/512 physical) All four drives make up a RAID 10 array. Stripe: 256kB Write Cache enabled Read Cache: intelligent StoreSave: Balance Thanks!

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  • Python CGI Premature end of script error depending on script parameters.

    - by nickengland
    I have a python script which should parse a file and produce some output to disk, as well as returning a webpage linking to the outputted files. When run with a file posted from the HTML form I get no HTML output back, just a 500 error page and the error_log contains the line: [Mon Apr 19 15:03:23 2010] [error] [client xxx.xxx.121.79] Premature end of script headers: uploadcml.py, referer: http://xxx.ch.cam.ac.uk:9000/ However, the files which the script should be saving are indeed saved to disk. If I run it without any arguments, the script returns the correct HTML indicating no file was parsed. All the information I have found on the web about Premature end of script headers implies it is due to either a missing header, or lack of permissions on the python script but neither can apply to me. The first lines of the script are: #!/home/nwe23/bin/bin/python import cgitb; cgitb.enable() import cgi import pybel,openbabel import random print "Content-Type: text/html" print so when run, I can see no way for it to fail to output the header, and it DOES output the header when run without a file to parse, but when given a file produces the error(but still parsed the file and saves the output to disk!). Does anyone know how this is happening and what can be done to fix it? I have tried adding wrongly-indented gibberish (such as foobar) at various points in the file, and this results in adding an indent error to the error_log wherever it is, even if its the very last line in the script. The Premature script headers error remains though. Does this mean the script is executing all the way through?

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  • Changes in gcc/persistence of optimization flags gcc/C

    - by gnometorule
    Just curious. Using gcc/gdb under Ubuntu 9.10. Reading a C book that also often gives the disassembly of the object file. When reading in January, my disassembly looks a lot like the book's; now, it's quite different - possibly more optimized (I notice some re-arrangements in the assembly code now that, at least in the files I checked, look optimized). I have used optimization options -O1 - -O3 for gcc between the first and second read, but not before the first. (1) Is the use of optimization options persistent, aka, if you use them once, you'll use them until switching them off? That would be weird (browsed man file and at least did not see anything to that sort). In the unlikely case that it is true, how do you switch them off? (2) Has gcc's assembly changed through any recent upgrade? (3) Does gcc sometimes produce (significantly) different assembly code although same compile options are chosen? Thanks much.

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  • ICC vs GCC - Optimization and CPU architecture

    - by Rayne
    Hi all, I'm interested in knowing how GCC differs from Intel's ICC in terms of the optimization levels and catering to specific processor architecture. I'm using GCC 4.1.2 20070626 and ICC v11.1 for Linux. How does ICC's optimization levels (O1 to O3) differ from GCC, if they differ at all? The ICC is able to cater specifically to different architectures (IA-32, intel64 and IA-64). I've read that GCC has the -march compiler option which I think is similar, but I can't find a list of the options to use. I'm using Intel Xeon X5570, which is 64-bit. Are there any other GCC compiler options I could use that would cater my applications for 64-bit Intel CPUs? Thank you. Regards, Rayne

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  • Query optimization

    - by Lijo
    Hi Team, I am trying to learn SQL query optimization using SQL Server 2005. However, I did not find any practical example where I can improve performance by tweaking query alone. Can you please list some example queries - prior and after optimization? It has to be query tuning – not adding index, not making covering index, not making any alteration to table. No change is supposed to be done on table and index. [ I understand that indexes are important. This is only for learning purpose] It would be great if you can exaplain using temp table instead of refering any sample databases like adventureworks. Expecting your support... Thanks Lijo

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  • small string optimization for vector?

    - by BuschnicK
    I know several (all?) STL implementations implement a "small string" optimization where instead of storing the usual 3 pointers for begin, end and capacity a string will store the actual character data in the memory used for the pointers if sizeof(characters) <= sizeof(pointers). I am in a situation where I have lots of small vectors with an element size <= sizeof(pointer). I cannot use fixed size arrays, since the vectors need to be able to resize dynamically and may potentially grow quite large. However, the median (not mean) size of the vectors will only be 4-12 bytes. So a "small string" optimization adapted to vectors would be quite useful to me. Does such a thing exist? I'm thinking about rolling my own by simply brute force converting a vector to a string, i.e. providing a vector interface to a string. Good idea?

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  • Will spreading your servers load not just consume more recourses

    - by Saif Bechan
    I am running a heavy real-time updating website. The amount of recourses needed per user are quite high, ill give you an example. Setup Every visit The application is php/mysql so on every visit static and dynamic content is loaded. Recourses: apache,php,mysql Every second (no more than a second will just be too long) The website needs to be updated real-time so every second there is an ajax call thats updates the website. Recourses: jQuery,apache,php,mysql Avarage spending for single user (spending one minute and visited 3 pages) Apache: +/- 63 requests / responsess serving static and dynamic content (img,css,js,html) php: +/- 63 requests / responses mysql: +/- 63 requests / responses jquery: +/- 60 requests / responses Optimization I want to optimize this process, but I think that maybe it would be just the same in the end. Before implementing and testing (which will take weeks) I wanted to have some second opinions from you guys. Every visit I want to start off with having nginx in the front and work as a proxy to deliver the static content. Recources: Dynamic: apache,php,mysql Static: nginx This will spread the load on apache a lot. Every Second For the script that loads every second I want to set up Node.js server side javascript with nginx in te front. I want to set it up that jquery makes a request ones a minute, and node.js streams the data to the client every second. Recources: jQuery,nginx,node.js,mysql Avarage spending for single user (spending one minute and visited 3 pages) Nginx: 4 requests / responsess serving mostly static conetent(img,css,js) Apache: 3 requests only the pages php: 3 requests only the pages node.js: 1 request / 60 responses jquery: 1 request / 60 responses mysql: 63 requests / responses Optimization As you can see in the optimisation the load from Apache and PHP are lifted and places on nginx and node.js. These are known for there light footprint and good performance. But I am having my doubts, because there are still 2 programs extra loaded in the memory and they consume cpu. So it it better to have less programs that do the job, or more. Before I am going to spend a lot of time setting this up I would like to know if it will be worth the while.

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  • Drop caches in Linux

    - by BerserkEVA
    I have an embedded Geode-based application server with 512MB RAM and I'm about to try to maximize free memory during applications workload, which uses MySQL database 5.5 with InnoDB quite aggressively. As part of the whole optimization I'd want to introduce echo 1 > /proc/sys/vm/drop_caches sleep 5 echo 0 > /proc/sys/vm/drop_caches in crontab. How often is it safe to execute something like this? Any other observation/suggestion is welcome.

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  • Big O, how do you calculate/approximate it?

    - by Sven
    Most people with a degree in CS will certainly know what Big O stands for. It helps us to measure how (in)efficient an algorithm really is and if you know in what category the problem you are trying to solve lays in you can figure out if it is still possible to squeeze out that little extra performance.* But I'm curious, how do you calculate or approximate the complexity of your algorithms? *: but as they say, don't overdo it, premature optimization is the root of all evil, and optimization without a justified cause should deserve that name as well.

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  • how to see the optimized code in c

    - by sganesh
    I can examine the optimization using profiler, size of the executable file and time to take for the execution. I can get the result of the optimization. But I have these questions, How to get the optimized C code. Which algorithm or method used by C to optimize a code. Thanks in advance.

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  • Does unit testing lead to premature generalization (specifically in the context of C++)?

    - by Martin
    Preliminary notes I'll not go into the distinction of the different kinds of test there are, there are already a few questions on these sites regarding that. I'll take what's there and that says: unit testing in the sense of "testing the smallest isolatable unit of an application" from which this question actually derives The isolation problem What is the smallest isolatable unit of a program. Well, as I see it, it (highly?) depends on what language you are coding in. Micheal Feathers talks about the concept of a seam: [WEwLC, p31] A seam is a place where you can alter behavior in your program without editing in that place. And without going into the details, I understand a seam -- in the context of unit testing -- to be a place in a program where your "test" can interface with your "unit". Examples Unit test -- especially in C++ -- require from the code under test to add more seams that would be strictly called for for a given problem. Example: Adding a virtual interface where non-virtual implementation would have been sufficient Splitting -- generalizing(?) -- a (smallish) class further "just" to facilitate adding a test. Splitting a single-executable project into seemingly "independent" libs, "just" to facilitate compiling them independently for the tests. The question I'll try a few versions that hopefully ask about the same point: Is the way that Unit Tests require one to structure an application's code "only" beneficial for the unit tests or is it actually beneficial to the applications structure. Is the generalization code need to exhibit to be unit-testable useful for anything but the unit tests? Does adding unit tests force one to generalize unnecessarily? Is the shape unit tests force on code "always" also a good shape for the code in general as seen from the problem domain? I remember a rule of thumb that said don't generalize until you need to / until there's a second place that uses the code. With Unit Tests, there's always a second place that uses the code -- namely the unit test. So is this reason enough to generalize?

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  • Does Your Business Really Need a Search Engine Optimization Specialist?

    If you're an individual or an organization planning to employ a search engine optimization professional, you might first want to consider the possibility of doing this work yourself. Certainly, a search engine optimization consultant can boost your site and perhaps help save you time and effort, yet the fact is that SEO is hardly an advanced science, and there are just a handful of authentic professionals within the field. So, if you depend on somebody else to be in charge of your search engine optimization, there's a high probability that the person will not possess a great deal more knowledge than you. And if you lack any knowledge, all the relevant information is easy to obtain.

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  • Performance problems when running Java desktop applications on Citrix Metaframe

    - by demetriusnunes
    We have a desktop Java application running within a Citrix Metaframe server farm and the performance, specially while starting up the app, is very unreliable. Sometimes it takes 15 seconds and sometimes it takes over a minute. It's really unpredicatable. Is there any way to optimize running Java desktop applications within Citrix Metaframe Terminal server sessions to a more reliable performance level? Are there any optimization directed specifically toward Java, such as pre-load JVMs or something like that? Any help would be greatly appreciated.

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  • Options to optimize lotus notes 8.5.X

    - by Jakub
    Has anyone found actually useful optimization methods for the bulky, fat, eclipse giant, nuissance that is Lotus Notes 8.5? I want it to be fast, and not eat up system resources like crazy while I run it ALL day (as it is my company's corporate mail / cal / scheduling solution). I've tried various hacks for the JVM heap size (if I recall correctly). None really bring a performance improvement. I have a dual core cpu, if that helps (I tried going the route of optimizing JAVA for 2 cores in hopes it would work, but seen no speed improvement). Notes is just sooo bloated, anyone have any suggestions to optimize/mod this thing so it is more responsive and less of a resource hog. Note: I don't want to switch to the web version, or the standard stripped down versions, I am aware of those, I just cannot since we don't run those internally for the company.

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  • Fusion 3.1 and Parallels 6 for Win7 x64

    - by Ronnie
    I read in a recent article that Parallels Desktop 6 is faster almost everywhere than VMware Fusion. I was originally using Parallels 4 before passing to VMware due to the frequent Parallels crashes. As now I am using a lot Fusion on my Macbook on a big Win7 x64 virtualized development machine that I find too slow I am wondering if the announced speed up of Parallels V6 is justified to come back to it. As a test I converted my Fusion 3.1 to a trial of Parallels Desktop 6 and my Windows Experience Index passed from 4.7 of Fusion to 4.5 on Parallels 6 so apparently the virtualized machine is not seeing that speed benefit. Is there any optimization to set up on Parallels to increase the WEI or should I stay with Fusion (and in this case this kind of articles is just marketing stuff)?

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