Search Results

Search found 22292 results on 892 pages for 'image optimization'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 197/892 | < Previous Page | 193 194 195 196 197 198 199 200 201 202 203 204  | Next Page >

  • "Anagram solver" based on statistics rather than a dictionary/table?

    - by James M.
    My problem is conceptually similar to solving anagrams, except I can't just use a dictionary lookup. I am trying to find plausible words rather than real words. I have created an N-gram model (for now, N=2) based on the letters in a bunch of text. Now, given a random sequence of letters, I would like to permute them into the most likely sequence according to the transition probabilities. I thought I would need the Viterbi algorithm when I started this, but as I look deeper, the Viterbi algorithm optimizes a sequence of hidden random variables based on the observed output. I am trying to optimize the output sequence. Is there a well-known algorithm for this that I can read about? Or am I on the right track with Viterbi and I'm just not seeing how to apply it?

    Read the article

  • How to insert zeros between bits in a bitmap?

    - by anatolyg
    I have some performance-heavy code that performs bit manipulations. It can be reduced to the following well-defined problem: Given a 13-bit bitmap, construct a 26-bit bitmap that contains the original bits spaced at even positions. To illustrate: 0000000000000000000abcdefghijklm (input, 32 bits) 0000000a0b0c0d0e0f0g0h0i0j0k0l0m (output, 32 bits) I currently have it implemented in the following way in C: if (input & (1 << 12)) output |= 1 << 24; if (input & (1 << 11)) output |= 1 << 22; if (input & (1 << 10)) output |= 1 << 20; ... My compiler (MS Visual Studio) turned this into the following: test eax,1000h jne 0064F5EC or edx,1000000h ... (repeated 13 times with minor differences in constants) I wonder whether i can make it any faster. I would like to have my code written in C, but switching to assembly language is possible. Can i use some MMX/SSE instructions to process all bits at once? Maybe i can use multiplication? (multiply by 0x11111111 or some other magical constant) Would it be better to use condition-set instruction (SETcc) instead of conditional-jump instruction? If yes, how can i make the compiler produce such code for me? Any other idea how to make it faster? Any idea how to do the inverse bitmap transformation (i have to implement it too, bit it's less critical)?

    Read the article

  • Optimizing an embedded SELECT query in mySQL

    - by Crazy Serb
    Ok, here's a query that I am running right now on a table that has 45,000 records and is 65MB in size... and is just about to get bigger and bigger (so I gotta think of the future performance as well here): SELECT count(payment_id) as signup_count, sum(amount) as signup_amount FROM payments p WHERE tm_completed BETWEEN '2009-05-01' AND '2009-05-30' AND completed > 0 AND tm_completed IS NOT NULL AND member_id NOT IN (SELECT p2.member_id FROM payments p2 WHERE p2.completed=1 AND p2.tm_completed < '2009-05-01' AND p2.tm_completed IS NOT NULL GROUP BY p2.member_id) And as you might or might not imagine - it chokes the mysql server to a standstill... What it does is - it simply pulls the number of new users who signed up, have at least one "completed" payment, tm_completed is not empty (as it is only populated for completed payments), and (the embedded Select) that member has never had a "completed" payment before - meaning he's a new member (just because the system does rebills and whatnot, and this is the only way to sort of differentiate between an existing member who just got rebilled and a new member who got billed for the first time). Now, is there any possible way to optimize this query to use less resources or something, and to stop taking my mysql resources down on their knees...? Am I missing any info to clarify this any further? Let me know... EDIT: Here are the indexes already on that table: PRIMARY PRIMARY 46757 payment_id member_id INDEX 23378 member_id payer_id INDEX 11689 payer_id coupon_id INDEX 1 coupon_id tm_added INDEX 46757 tm_added, product_id tm_completed INDEX 46757 tm_completed, product_id

    Read the article

  • "variable tracking" is eating my compile time!

    - by wowus
    I have an auto-generated file which looks something like this... static void do_SomeFunc1(void* parameter) { // Do stuff. } // Continues on for another 4000 functions... void dispatch(int id, void* parameter) { switch(id) { case ::SomeClass1::id: return do_SomeFunc1(parameter); case ::SomeClass2::id: return do_SomeFunc2(parameter); // This continues for the next 4000 cases... } } When I build it like this, the build time is enormous. If I inline all the functions automagically into their respective cases using my script, the build time is cut in half. GCC 4.5.0 says ~50% of the build time is being taken up by "variable tracking" when I use -ftime-report. What does this mean and how can I speed compilation while still maintaining the superior cache locality of pulling out the functions from the switch? EDIT: Interestingly enough, the build time has exploded only on debug builds, as per the following profiling information of the whole project (which isn't just the file in question, but still a good metric; the file in question takes the most time to build): Debug: 8 minutes 50 seconds Release: 4 minutes, 25 seconds

    Read the article

  • Is SQL DATEDIFF(year, ..., ...) an Expensive Computation?

    - by rlb.usa
    I'm trying to optimize up some horrendously complicated SQL queries because it takes too long to finish. In my queries, I have dynamically created SQL statements with lots of the same functions, so I created a temporary table where each function is only called once instead of many, many times - this cut my execution time by 3/4. So my question is, can I expect to see much of a difference if say, 1,000 datediff computations are narrowed to 100?

    Read the article

  • Where is the bottleneck in this code?

    - by Mikhail
    I have the following tight loop that makes up the serial bottle neck of my code. Ideally I would parallelize the function that calls this but that is not possible. //n is about 60 for (int k = 0;k < n;k++) { double fone = z[k*n+i+1]; double fzer = z[k*n+i]; z[k*n+i+1]= s*fzer+c*fone; z[k*n+i] = c*fzer-s*fone; } Are there any optimizations that can be made such as vectorization or some evil inline that can help this code? I am looking into finding eigen solutions of tridiagonal matrices. http://www.cimat.mx/~posada/OptDoglegGraph/DocLogisticDogleg/projects/adjustedrecipes/tqli.cpp.html

    Read the article

  • most efficient method of turning multiple 1D arrays into columns of a 2D array

    - by Ty W
    As I was writing a for loop earlier today, I thought that there must be a neater way of doing this... so I figured I'd ask. I looked briefly for a duplicate question but didn't see anything obvious. The Problem: Given N arrays of length M, turn them into a M-row by N-column 2D array Example: $id = [1,5,2,8,6] $name = [a,b,c,d,e] $result = [[1,a], [5,b], [2,c], [8,d], [6,e]] My Solution: Pretty straight forward and probably not optimal, but it does work: <?php // $row is returned from a DB query // $row['<var>'] is a comma separated string of values $categories = array(); $ids = explode(",", $row['ids']); $names = explode(",", $row['names']); $titles = explode(",", $row['titles']); for($i = 0; $i < count($ids); $i++) { $categories[] = array("id" => $ids[$i], "name" => $names[$i], "title" => $titles[$i]); } ?> note: I didn't put the name = value bit in the spec, but it'd be awesome if there was some way to keep that as well.

    Read the article

  • Does the order of columns in a query matter?

    - by James Simpson
    When selecting columns from a MySQL table, is performance affected by the order that you select the columns as compared to their order in the table (not considering indexes that may cover the columns)? For example, you have a table with rows uid, name, bday, and you have the following query. SELECT uid, name, bday FROM table Does MySQL see the following query any differently and thus cause any sort of performance hit? SELECT uid, bday, name FROM table

    Read the article

  • approximating log10[x^k0 + k1]

    - by Yale Zhang
    Greetings. I'm trying to approximate the function Log10[x^k0 + k1], where .21 < k0 < 21, 0 < k1 < ~2000, and x is integer < 2^14. k0 & k1 are constant. For practical purposes, you can assume k0 = 2.12, k1 = 2660. The desired accuracy is 5*10^-4 relative error. This function is virtually identical to Log[x], except near 0, where it differs a lot. I already have came up with a SIMD implementation that is ~1.15x faster than a simple lookup table, but would like to improve it if possible, which I think is very hard due to lack of efficient instructions. My SIMD implementation uses 16bit fixed point arithmetic to evaluate a 3rd degree polynomial (I use least squares fit). The polynomial uses different coefficients for different input ranges. There are 8 ranges, and range i spans (64)2^i to (64)2^(i + 1). The rational behind this is the derivatives of Log[x] drop rapidly with x, meaning a polynomial will fit it more accurately since polynomials are an exact fit for functions that have a derivative of 0 beyond a certain order. SIMD table lookups are done very efficiently with a single _mm_shuffle_epi8(). I use SSE's float to int conversion to get the exponent and significand used for the fixed point approximation. I also software pipelined the loop to get ~1.25x speedup, so further code optimizations are probably unlikely. What I'm asking is if there's a more efficient approximation at a higher level? For example: Can this function be decomposed into functions with a limited domain like log2((2^x) * significand) = x + log2(significand) hence eliminating the need to deal with different ranges (table lookups). The main problem I think is adding the k1 term kills all those nice log properties that we know and love, making it not possible. Or is it? Iterative method? don't think so because the Newton method for log[x] is already a complicated expression Exploiting locality of neighboring pixels? - if the range of the 8 inputs fall in the same approximation range, then I can look up a single coefficient, instead of looking up separate coefficients for each element. Thus, I can use this as a fast common case, and use a slower, general code path when it isn't. But for my data, the range needs to be ~2000 before this property hold 70% of the time, which doesn't seem to make this method competitive. Please, give me some opinion, especially if you're an applied mathematician, even if you say it can't be done. Thanks.

    Read the article

  • Is this implementation truely tail-recursive?

    - by CFP
    Hello everyone! I've come up with the following code to compute in a tail-recursive way the result of an expression such as 3 4 * 1 + cos 8 * (aka 8*cos(1+(3*4))) The code is in OCaml. I'm using a list refto emulate a stack. type token = Num of float | Fun of (float->float) | Op of (float->float->float);; let pop l = let top = (List.hd !l) in l := List.tl (!l); top;; let push x l = l := (x::!l);; let empty l = (l = []);; let pile = ref [];; let eval data = let stack = ref data in let rec _eval cont = match (pop stack) with | Num(n) -> cont n; | Fun(f) -> _eval (fun x -> cont (f x)); | Op(op) -> _eval (fun x -> cont (op x (_eval (fun y->y)))); in _eval (fun x->x) ;; eval [Fun(fun x -> x**2.); Op(fun x y -> x+.y); Num(1.); Num(3.)];; I've used continuations to ensure tail-recursion, but since my stack implements some sort of a tree, and therefore provides quite a bad interface to what should be handled as a disjoint union type, the call to my function to evaluate the left branch with an identity continuation somehow irks a little. Yet it's working perfectly, but I have the feeling than in calling the _eval (fun y->y) bit, there must be something wrong happening, since it doesn't seem that this call can replace the previous one in the stack structure... Am I misunderstanding something here? I mean, I understand that with only the first call to _eval there wouldn't be any problem optimizing the calls, but here it seems to me that evaluation the _eval (fun y->y) will require to be stacked up, and therefore will fill the stack, possibly leading to an overflow... Thanks!

    Read the article

  • Data Access from single table in sql server 2005 is too slow

    - by Muhammad Kashif Nadeem
    Following is the script of table. Accessing data from this table is too slow. SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Emails]( [id] [int] IDENTITY(1,1) NOT NULL, [datecreated] [datetime] NULL CONSTRAINT [DF_Emails_datecreated] DEFAULT (getdate()), [UID] [nvarchar](250) COLLATE Latin1_General_CI_AS NULL, [From] [nvarchar](100) COLLATE Latin1_General_CI_AS NULL, [To] [nvarchar](100) COLLATE Latin1_General_CI_AS NULL, [Subject] [nvarchar](max) COLLATE Latin1_General_CI_AS NULL, [Body] [nvarchar](max) COLLATE Latin1_General_CI_AS NULL, [HTML] [nvarchar](max) COLLATE Latin1_General_CI_AS NULL, [AttachmentCount] [int] NULL, [Dated] [datetime] NULL ) ON [PRIMARY] Following query takes 50 seconds to fetch data. select id, datecreated, UID, [From], [To], Subject, AttachmentCount, Dated from emails If I include Body and Html in select then time is event worse. indexes are on: id unique clustered From Non unique non clustered To Non unique non clustered Tabls has currently 180000+ records. There might be 100,000 records each month so this will become more slow as time will pass. Does splitting data into two table will solve the problem? What other indexes should be there?

    Read the article

  • How to make html image clickable inside a TextView

    - by Gonan
    I have the following text in a string in the resources file: <a href="mailto:[email protected]">&lt;img src="mail_big" /&gt;</a> It shows the image fine (I implemented ImageGetter) but it is not clickable. I have tried adding the Linkify thingy but I don't think it's meant for this case, and so it doesn't work. The setMovementMethod doesn't work either. I have tried different combinations of the above: <a href="mailto:[email protected]">&lt;img src="mail_big" /&gt;hello</a> Here, even the "hello" part is not clickable (neither blue nor underlined). <a href="mailto:[email protected]"><img src="mail_big" /></a> This doesn't even show the image. &lt;a href="mailto:[email protected]"&gt;&lt;img src="mail_big" /&gt;&lt;/a&gt; If I just write the email, without the <a> tag it works perfectly, but I would like to use the image of an envelope that the user can click on. It's not possible to use an imagebutton because this text is in the middle of a string and so I can't split it. Any ideas? Thanks! EDIT: I found a solution or rather found how to do it correctly. All I had to do was adding the setMovementMethod call before the call to setText in the TextView and ALSO, and COMPLETELY NECESSARY, remove the attribute "android:autoLink="all" from the layout. Apparently, parsing mails and urls in a string is mutually exclusive to interpreting the link tags in a string. So one or the other but not both. Finally my layout is just a TextView with nothing special, just width and height. The activity is like this: TextView tv = (TextView)findViewById(R.id.about_text); tv.setMovementMethod(LinkMovementMethod.getInstance()); tv.setText(Html.fromHtml(getString(R.string.about_content), new ImageGetter(), null)); And the string is like this: <string name="about_content"><a href="mailto:[email protected]"><img src="mail" /></a></string>

    Read the article

  • How to store static content across branches in a single location in version control

    - by Shravan
    [Just a random thought] I have a pdf doc that is downloaded when the user clicks on 'help' on my website. Now, this is a pretty huge document and is saved in version control (SVN) and is thus copied for all branches that exist in SVN. This is static content and something that developers are not working on, and does not change often. Is there a more efficient way to store it (that would not hamper local deployments) that would make SVN checkouts and updates relatively faster. I know the benefit we get is not huge, this is something that came to my head none the less.

    Read the article

  • How to display an image when aAsynch post back is happening

    - by Nasser Hajloo
    I have an Ajaxable application which has some UpdateProgress for each postBack events. everything is good and working great. I want to display another Indicator in my SiteMapPath bar which shows a post back is happening no matter what. For example when user clicks on a button an UpdateProgress display an Indicator Image in central part of application. I want to display another image ( for every postbacks not only for one) in top of application toolbar. Currently I use a simple Flag out ther and I want to use an indicator instead of that flag when ever a postback happens Thank you in advance

    Read the article

  • unroll nested for loops in C++

    - by Hristo
    How would I unroll the following nested loops? for(k = begin; k != end; ++k) { for(j = 0; j < Emax; ++j) { for(i = 0; i < N; ++i) { if (j >= E[i]) continue; array[k] += foo(i, tr[k][i], ex[j][i]); } } } I tried the following, but my output isn't the same, and it should be: for(k = begin; k != end; ++k) { for(j = 0; j < Emax; ++j) { for(i = 0; i+4 < N; i+=4) { if (j >= E[i]) continue; array[k] += foo(i, tr[k][i], ex[j][i]); array[k] += foo(i+1, tr[k][i+1], ex[j][i+1]); array[k] += foo(i+2, tr[k][i+2], ex[j][i+2]); array[k] += foo(i+3, tr[k][i+3], ex[j][i+3]); } if (i < N) { for (; i < N; ++i) { if (j >= E[i]) continue; array[k] += foo(i, tr[k][i], ex[j][i]); } } } } I will be running this code in parallel using Intel's TBB so that it takes advantage of multiple cores. After this is finished running, another function prints out what is in array[] and right now, with my unrolling, the output isn't identical. Any help is appreciated. Thanks, Hristo

    Read the article

  • Using new Image().src for click tracking

    - by razass
    I am attempting to figure out why this click tracker isn't working. The code was written by another developer so I am not entirely sure if this ever did work. function trackSponsor(o, p) { (new Image()).src = PATH_BASE + 'click/' + p + '/' + o + "?_cache=" + (+(new Date())); return false; } From what I can gather is that when this function is called it 'creates a new image' to fire a php script asynchronously. According to Firebug, the request is made however it is 'aborted' ~30ms in. The odd thing is that it will 'sometimes' work as in 1 in every 10+ regardless of the browser. I would much rather fix this so that it works instead of re-writing it as an ajax request. Any help is appreciated. Thanks in advance.

    Read the article

  • What does ER_WARN_FIELD_RESOLVED mean?

    - by VolkerK
    When SHOW WARNINGS after a EXPLAIN EXTENDED shows a Note 1276 Field or reference 'test.foo.bar' of SELECT #2 was resolved in SELECT #1 what exactly does that mean and what impact does it have? In my case it prevents mysql from using what seems to be a perfectly good index. But it's not about fixing that specific query (as it is an irrelevant test). I found http://dev.mysql.com/doc/refman/5.0/en/error-messages-server.html butError: 1276 SQLSTATE: HY000 (ER_WARN_FIELD_RESOLVED) Message: Field or reference '%s%s%s%s%s' of SELECT #%d was resolved in SELECT #%d isn't much of an explaination.

    Read the article

  • How to place images on top of each other in java

    - by Haxed
    Hi, I have a background image of a road, which I have displayed on a JFrame using an ImageIcon. I want to put a car on top of that background image at a certain (x,y) location. I tried using another ImageIcon and the background does not appear when I run the program , however the car does. import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; public class Gui extends JFrame { private ImageIcon northcar = new ImageIcon("src/north.gif"); private ImageIcon usIcon = new ImageIcon("src/trafficLight.jpg"); public Gui() { add(new JLabel(usIcon)); // background image does not appear after the i added the northcar label add(new JLabel(northcar)); // this picture can be seen } public static void main(String[] args) { Gui frame = new Gui(); frame.setTitle("TestImageIcon"); frame.setLocationRelativeTo(null); // Center the frame frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setBounds(0, 0, 650, 650); frame.setVisible(true); } } I heard about using a canvas but have no clue. Any ideas ? Many Thanks

    Read the article

  • Nodes set of the same type with if-test. Make it less.

    - by Kalinin
    How to make the code more beautiful (compact)? <xsl:template match="part"> <table class="part"> <xsl:if test="name != ''"> <tr> <td>????????</td><td><xsl:value-of select="name"/></td> </tr> </xsl:if> <xsl:if test="model != ''"> <tr> <td>??????</td><td><xsl:value-of select="model"/></td> </tr> </xsl:if> <xsl:if test="year != ''"> <tr> <td>???</td><td><xsl:value-of select="year"/></td> </tr> </xsl:if> <xsl:if test="glass_type != ''"> <tr> <td>???</td><td><xsl:value-of select="glass_type"/></td> </tr> </xsl:if> <xsl:if test="scancode != ''"> <tr> <td>???????</td><td><xsl:value-of select="scancode"/></td> </tr> </xsl:if> <xsl:if test="eurocode != ''"> <tr> <td>???????</td><td><xsl:value-of select="eurocode"/></td> </tr> </xsl:if> <xsl:if test="coment != ''"> <tr> <td>???????????</td><td><xsl:value-of select="coment"/></td> </tr> </xsl:if> <xsl:if test="glass_size != ''"> <tr> <td>??????</td><td><xsl:value-of select="glass_size"/></td> </tr> </xsl:if> <xsl:if test="vendor != ''"> <tr> <td>?????????????</td><td><xsl:value-of select="vendor"/></td> </tr> </xsl:if> <xsl:if test="trademark != ''"> <tr> <td>???????? ?????</td><td><xsl:value-of select="trademark"/></td> </tr> </xsl:if> <xsl:if test="fprice != ''"> <tr> <td>????</td><td><xsl:value-of select="fprice"/></td> </tr> </xsl:if> </table> </xsl:template> Update: i wrote: <my:translations xmlns:my="my:my"> <w e="name" r="????????"/> <w e="model" r="??????"/> <w e="year" r="???"/> <w e="glass_type" r="???"/> <w e="scancode" r="???????"/> <w e="eurocode" r="???????"/> <w e="comment" r="???????????"/> <w e="glass_size" r="??????"/> <w e="vendor" r="?????????????"/> <w e="trademark" r="???????? ?????"/> <w e="fprice" r="????"/> </my:translations> <xsl:value-of select="//w/@r"/> And have no result from this code. Is it normal? And how can i get new element w?

    Read the article

  • Mysql - help me optimize this query (improved question)

    - by sandeepan-nath
    About the system: - There are tutors who create classes and packs - A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below. Following is the concerned query SELECT SUM(DISTINCT( t.tag LIKE "%Dictatorship%" )) AS key_1_total_matches, SUM(DISTINCT( t.tag LIKE "%democracy%" )) AS key_2_total_matches, COUNT(DISTINCT( od.id_od )) AS tutor_popularity, CASE WHEN ( IF(( wc.id_wc > 0 ), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'classes_published', CASE WHEN ( IF(( lp.id_lp > 0 ), ( lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'packs_published', td . *, u . * FROM tutor_details AS td JOIN users AS u ON u.id_user = td.id_user LEFT JOIN learning_packs_tag_relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN learning_packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN learning_packs_categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN learning_packs_categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN learning_pack_content AS lpct ON ( lp.id_lp = lpct.id_lp ) LEFT JOIN webclasses_tag_relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN webclasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN learning_packs_categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN learning_packs_categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN order_details AS od ON td.id_tutor = od.id_author LEFT JOIN orders AS o ON od.id_order = o.id_order LEFT JOIN tutors_tag_relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor JOIN tags AS t ON ( t.id_tag = ttagrels.id_tag ) OR ( t.id_tag = lptagrels.id_tag ) OR ( t.id_tag = wtagrels.id_tag ) WHERE ( u.country = 'IE' OR u.country IN ( 'INT' ) ) AND CASE WHEN ( ( t.id_tag = lptagrels.id_tag ) AND ( lp.id_lp 0 ) ) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( ( t.id_tag = wtagrels.id_tag ) AND ( wc.id_wc 0 ) ) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( od.id_od 0 ) THEN od.id_author = td.id_tutor AND o.order_status = 'paid' AND CASE WHEN ( od.id_wc 0 ) THEN od.can_attend_class = 1 ELSE 1 END ELSE 1 END GROUP BY td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 ORDER BY tutor_popularity DESC, u.surname ASC, u.name ASC LIMIT 0, 20 The problem The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query rises alarmingly for heavier data and for the current data I have it is like 25 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable. It is possible that some of the delay is being caused because all the possible fields have not yet been indexed. The tag field of tags table is indexed. Is there something faulty with the query? What can be the reason behind 20+ seconds of execution time? How tags work in this system? When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc. When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc. tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table. The explain query output:- Please see this screenshot - http://www.test.examvillage.com/Explain_query.jpg

    Read the article

  • MySQL won't use index for query?

    - by Jack Sleight
    I have this table: CREATE TABLE `point` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `siteid` INT(11) NOT NULL, `lft` INT(11) DEFAULT NULL, `rgt` INT(11) DEFAULT NULL, `level` SMALLINT(6) DEFAULT NULL, PRIMARY KEY (`id`), KEY `point_siteid_site_id` (`siteid`), CONSTRAINT `point_siteid_site_id` FOREIGN KEY (`siteid`) REFERENCES `site` (`id`) ON DELETE CASCADE ) ENGINE=INNODB AUTO_INCREMENT=35 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci And this query: SELECT * FROM `point` WHERE siteid = 1; Which results in this EXPLAIN information: +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ | 1 | SIMPLE | point | ALL | point_siteid_site_id | NULL | NULL | NULL | 6 | Using where | +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ Question is, why isn't the query using the point_siteid_site_id index?

    Read the article

  • Filtering with joined tables

    - by viraptor
    I'm trying to get some query performance improved, but the generated query does not look the way I expect it to. The results are retrieved using: query = session.query(SomeModel). options(joinedload_all('foo.bar')). options(joinedload_all('foo.baz')). options(joinedload('quux.other')) What I want to do is filter on the table joined via 'first', but this way doesn't work: query = query.filter(FooModel.address == '1.2.3.4') It results in a clause like this attached to the query: WHERE foos.address = '1.2.3.4' Which doesn't do the filtering in a proper way, since the generated joins attach tables foos_1 and foos_2. If I try that query manually but change the filtering clause to: WHERE foos_1.address = '1.2.3.4' AND foos_2.address = '1.2.3.4' It works fine. The question is of course - how can I achieve this with sqlalchemy itself?

    Read the article

  • Will the compiler optimize escaping an inner loop?

    - by BCS
    The code I have looks like this (all uses of done shown): bool done = false; for(int i = 0; i < big; i++) { ... for(int j = 0; j < wow; j++) { ... if(foo(i,j)) { done = true; break; } ... } if(done) break; ... } will any compilers convert it to this: for(int i = 0; i < big; i++) { ... for(int j = 0; j < wow; j++) { ... if(foo(i,j)) goto __done; // same as a labeled break if we had it ... } ... } __done:;

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 193 194 195 196 197 198 199 200 201 202 203 204  | Next Page >