Search Results

Search found 27144 results on 1086 pages for 'tail call optimization'.

Page 115/1086 | < Previous Page | 111 112 113 114 115 116 117 118 119 120 121 122  | Next Page >

• In PHP is faster to get a value from an if statement or from an array?

  - by Vittorio Vittori

  Maybe this is a stupid question but what is faster? <?php function getCss1 ($id = 0) { if ($id == 1) { return 'red'; } else if ($id == 2) { return 'yellow'; } else if ($id == 3) { return 'green'; } else if ($id == 4) { return 'blue'; } else if ($id == 5) { return 'orange'; } else { return 'grey'; } } function getCss2 ($id = 0) { $css[] = 'grey'; $css[] = 'red'; $css[] = 'yellow'; $css[] = 'green'; $css[] = 'blue'; $css[] = 'orange'; return $css[$id]; } echo getCss1(3); echo getCss2(3); ?> I suspect is faster the if statement but I prefere to ask!

  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

• Why is doing a top(1) on an indexed column in SQL Server slow?

  - by reinier

  I'm puzzled by the following. I have a DB with around 10 million rows, and (among other indices) on 1 column (campaignid_int) is an index. Now I have 700k rows where the campaignid is indeed 3835 For all these rows, the connectionid is the same. I just want to find out this connectionid. use messaging_db; SELECT TOP (1) connectionid FROM outgoing_messages WITH (NOLOCK) WHERE (campaignid_int = 3835) Now this query takes approx 30 seconds to perform! I (with my small db knowledge) would expect that it would take any of the rows, and return me that connectionid If I test this same query for a campaign which only has 1 entry, it goes really fast. So the index works. How would I tackle this and why does this not work? edit: estimated execution plan: select (0%) - top (0%) - clustered index scan (100%)

  Read the article

• MySQL Paritioning performance

  - by Imran Pathan

  Measured performance on key partitioned tables and normal tables separately. But we couldn't find any performance improvement with partitioning. Queries are pruned. Using MySQL 5.1.47 on RHEL 4. Table details: UserUsage - Will have entries for user mobile number and data usage for each date. Mobile number and Date as PRI KEY. UserProfile - Queries prev table and stores summary for each mobile number. Mobile number PRI KEY. CREATE TABLE `UserUsage` ( `Msisdn` decimal(20,0) NOT NULL, `Date` date NOT NULL, . . PRIMARY KEY USING BTREE (`Msisdn`,`Date`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 PARTITION BY KEY(Msisdn) PARTITIONS 50; CREATE TABLE `UserProfile` ( `Msisdn` decimal(20,0) NOT NULL, . . PRIMARY KEY (`Msisdn`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 PARTITION BY KEY(Msisdn) PARTITIONS 50; Second table is updated by query select and order by date in first table in a perl program, query is select * from UserUsage where Msisdn=number order by Date desc limit 7 [Process data in perl] update UserProfile values(....) where Msisdn=number explain partition for select, shows row being scanned in a particular partition only. Is something wrong with partition design or queries as partitioning is taking almost same or more time compared to normal tables?

  Read the article

• How can I Query only __key__ on a Google Appengine PolyModel child?

  - by Gabriel

  So the situation is: I want to optimize my code some for doing counting of records. So I have a parent Model class Base, a PolyModel class Entry, and a child class of Entry Article: How would I query Article.key so I can reduce the query load but only get the Article count. My first thought was to use: q = db.GqlQuery("SELECT __key__ from Article where base = :1", i_base) but it turns out GqlQuery doesn't like that because articles are actually stored in a table called Entry. Would it be possible to Query the class attribute? something like: q = db.GqlQuery("select __key__ from Entry where base = :1 and :2 in class", i_base, 'Article') neither of which work. Turns out the answer is even easier. But I am going to finish this question because I looked everywhere for this. q = db.GqlQuery("select __key__ from Entry where base = :1 and class = :2", i_base, 'Article')

  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

• Why is Javascript's Math.floor the slowest way to calculate floor in Javascript?

  - by z5h

  I'm generally not a fan of microbenchmarks. But this one has a very interesting result. http://ernestdelgado.com/archive/benchmark-on-the-floor/ It suggests that Math.floor is the SLOWEST way to calculate floor in Javascript. ~~n, n|n, n&n all being faster. This seems pretty shocking as I would expect that people implementing Javascript in today's modern browsers would be some pretty smart people. Does floor do something important that the other methods fail to do? Is there any reason to use it?

  Read the article

• Splitting tables by field to optimize MySQL?

  - by AK

  Do splitting fields into multiple tables ever yield faster queries? Consider the following two scenarios: Table1 ----------- int PersonID text Value1 float Value2 or Table1 ----------- int PersonID text Value1 Table2 ----------- int PersonID float Value2 If Value1 and Value2 are always being displayed together, I imagine Table1 is always faster because the second schema would require two SELECT statements. But are there any situations where you would choose the second? If the number of records were expected to be really large?

  Read the article

• Constructor being called again?

  - by Halo

  I have this constructor; public UmlDiagramEntity(ReportElement reportElement, int pageIndex, Controller controller) { super(reportElement.getX1(), reportElement.getY1(), reportElement.getX2(), reportElement.getY2()); setLayout(null); this.pageIndex = pageIndex; this.controller = controller; reportElements = reportElement.getInternalReportElements(); components = new ArrayList<AbstractEntity>(); changedComponentIndex = -1; PageListener p = new PageListener(); this.addMouseMotionListener(p); this.addMouseListener(p); setPage(); } And I have an update method in the same class; @Override public void update(ReportElement reportElement) { if (changedComponentIndex == -1) { super.update(reportElement); } else { reportElements = reportElement.getInternalReportElements(); if (components.size() == reportElements.size()) { if (!isCommitted) { if (reportElement.getType() == ReportElementType.UmlRelation) { if (checkInvolvementAndSet(changedComponentIndex)) { anchorEntity(changedComponentIndex); } else { resistChanges(changedComponentIndex); } return; } } ..................goes on When I follow the flow from the debugger, I see that when update is called, somewhere in the method, the program goes into the constructor and executes it all over again (super, pageIndex, etc.). Why does it go to the constructor :D I didn't tell it to go there. I can make a deeper analysis and see where it goes to the constructor if you want. By the way, changedComponentIndex is a static variable.

  Read the article

• Alternate User select interface in django admin to reduce page size on large site?

  - by David Eyk

  I have a Django-based site with roughly 300,000 User objects. Admin pages for objects with a ForeignKey field to User take a very long time to load as the resulting form is about 6MB in size. Of course, the resulting dropdown isn't particularly useful, either. Are there any off-the-shelf replacements for handling this case? I've been googling for a snippet or a blog entry, but haven't found anything yet. I'd like to have a smaller download size and a more usable interface.

  Read the article

• SEO Google - Navigation Title vs. Page Heading

  - by louism

  Hi, i was wondering if anyone knows if theres a connection between what a navigation item is named and the page heading it goes to - does this have an impact on SEO? so for example, if i had in my navigation menu an item called About Us, but when you click it you come to a page with the heading Learn Who We Are (i.e. wrapped in [h1] heading tags) because there isnt an exact one-to-one match, is that a bad thing in terms of SEO? thanks

  Read the article

• Optimize slow ranking query

  - by Juan Pablo Califano

  I need to optimize a query for a ranking that is taking forever (the query itself works, but I know it's awful and I've just tried it with a good number of records and it gives a timeout). I'll briefly explain the model. I have 3 tables: player, team and player_team. I have players, that can belong to a team. Obvious as it sounds, players are stored in the player table and teams in team. In my app, each player can switch teams at any time, and a log has to be mantained. However, a player is considered to belong to only one team at a given time. The current team of a player is the last one he's joined. The structure of player and team is not relevant, I think. I have an id column PK in each. In player_team I have: id (PK) player_id (FK -> player.id) team_id (FK -> team.id) Now, each team is assigned a point for each player that has joined. So, now, I want to get a ranking of the first N teams with the biggest number of players. My first idea was to get first the current players from player_team (that is one record top for each player; this record must be the player's current team). I failed to find a simple way to do it (tried GROUP BY player_team.player_id HAVING player_team.id = MAX(player_team.id), but that didn't cut it. I tried a number of querys that didn't work, but managed to get this working. SELECT COUNT(*) AS total, pt.team_id, p.facebook_uid AS owner_uid, t.color FROM player_team pt JOIN player p ON (p.id = pt.player_id) JOIN team t ON (t.id = pt.team_id) WHERE pt.id IN ( SELECT max(J.id) FROM player_team J GROUP BY J.player_id ) GROUP BY pt.team_id ORDER BY total DESC LIMIT 50 As I said, it works but looks very bad and performs worse, so I'm sure there must be a better way to go. Anyone has any ideas for optimizing this? I'm using mysql, by the way. Thanks in advance Adding the explain. (Sorry, not sure how to format it properly) id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t ALL PRIMARY NULL NULL NULL 5000 Using temporary; Using filesort 1 PRIMARY pt ref FKplayer_pt77082,FKplayer_pt265938,new_index FKplayer_pt77082 4 t.id 30 Using where 1 PRIMARY p eq_ref PRIMARY PRIMARY 4 pt.player_id 1 2 DEPENDENT SUBQUERY J index NULL new_index 8 NULL 150000 Using index

  Read the article

• Optimizing BeautifulSoup (Python) code

  - by user283405

  I have code that uses the BeautifulSoup library for parsing, but it is very slow. The code is written in such a way that threads cannot be used. Can anyone help me with this? I am using BeautifulSoup for parsing and than save into a DB. If I comment out the save statement, it still takes a long time, so there is no problem with the database. def parse(self,text): soup = BeautifulSoup(text) arr = soup.findAll('tbody') for i in range(0,len(arr)-1): data=Data() soup2 = BeautifulSoup(str(arr[i])) arr2 = soup2.findAll('td') c=0 for j in arr2: if str(j).find("<a href=") > 0: data.sourceURL = self.getAttributeValue(str(j),'<a href="') else: if c == 2: data.Hits=j.renderContents() #and few others... c = c+1 data.save() Any suggestions? Note: I already ask this question here but that was closed due to incomplete information.

  Read the article

• Avoid the use of loops (for) with R

  - by albergali

  Hi, I'm working with R and I have a code like this: i<-1 j<-1 for (i in 1:10) for (j in 1:100) if (data[i] == paths[j,1]) cluster[i,4] <- paths[j,2] where : data is a vector with 100 rows and 1 column paths is a matrix with 100 rows and 5 columns cluster is a matrix with 100 rows and 5 columns My question is: how could I avoid the use of "for" loops to iterate through the matrix? I don't know whether apply functions (lapply, tapply...) are useful in this case. This is a problem when j=10000 for example, because execution time is very long. Thank you

  Read the article

• Drawbacks of Dynamic Query in Sqlserver 2005 ?

  - by KuldipMCA

  I have using the many dynamic Query in my database for the procedures because my filter is not fix so i have taken @filter as parameter and pass in the procedure. Declare @query as varchar(8000) Declare @Filter as varchar(1000) set @query = 'Select * from Person.Address where 1=1 and ' + @Filter exec(@query) Like that my filter contain any Field from the table for comparison. It will affect my performance or not ? is there any alternate way to achieve this type of things

  Read the article

• Resize an image and maintain quality?

  - by JasonS

  Hi, I have a problem with resizing images. What happens is that if you upload a file larger than the stated parameters, the image is cropped, then saved at 100% quality. So if I upload a large jpeg which is 272Kb. The image is cropped by 100 odd pixels. The file size then goes up to 1.2Mb. We are saving images at a 100% quality. I assume that this is what is causing the problem. The image is exported from Photoshop at 30% quality which reduces the file size. Resaving the image at 100% quality creates the same image but I assume with a lot of redundant file data. Has anyone encountered this before? Does anyone have a solution? This is what we are using. $source_im = imagecreatefromjpeg ($file); $dest_im = imagecreatetruecolor ($newsize_x, $newsize_y); imagecopyresampled ( $dest_im, $source_im, 0, 0, $offset_x, $offset_y, $newsize_x, $newsize_y, $sourceWidth, $sourceHeight ); imagedestroy ($source_im); if ($greyscale) { $dest_im = $this->imageconvertgreyscale ($dest_im); } imagejpeg($dest_im, $save_to_file, $quality); break;

  Read the article

• Which fieldtype is best for storing PRICE values?

  - by BerggreenDK

  Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

  Read the article

• Fast format conversion open source library

  - by KindDragon

  Can someone advise me open source format conversion library? Optimized for SSE, SSE2. Formats for conversion: I420, YUY2, RGB(16-bit, 32-bit). I found only VirtualDub Kasumi library.

  Read the article

• Feedback on Optimizing C# NET Code Block

  - by Brett Powell

  I just spent quite a few hours reading up on TCP servers and my desired protocol I was trying to implement, and finally got everything working great. I noticed the code looks like absolute bollocks (is the the correct usage? Im not a brit) and would like some feedback on optimizing it, mostly for reuse and readability. The packet formats are always int, int, int, string, string. try { BinaryReader reader = new BinaryReader(clientStream); int packetsize = reader.ReadInt32(); int requestid = reader.ReadInt32(); int serverdata = reader.ReadInt32(); Console.WriteLine("Packet Size: {0} RequestID: {1} ServerData: {2}", packetsize, requestid, serverdata); List<byte> str = new List<byte>(); byte nextByte = reader.ReadByte(); while (nextByte != 0) { str.Add(nextByte); nextByte = reader.ReadByte(); } // Password Sent to be Authenticated string string1 = Encoding.UTF8.GetString(str.ToArray()); str.Clear(); nextByte = reader.ReadByte(); while (nextByte != 0) { str.Add(nextByte); nextByte = reader.ReadByte(); } // NULL string string string2 = Encoding.UTF8.GetString(str.ToArray()); Console.WriteLine("String1: {0} String2: {1}", string1, string2); // Reply to Authentication Request MemoryStream stream = new MemoryStream(); BinaryWriter writer = new BinaryWriter(stream); writer.Write((int)(1)); // Packet Size writer.Write((int)(requestid)); // Mirror RequestID if Authenticated, -1 if Failed byte[] buffer = stream.ToArray(); clientStream.Write(buffer, 0, buffer.Length); clientStream.Flush(); } I am going to be dealing with other packet types as well that are formatted the same (int/int/int/str/str), but different values. I could probably create a packet class, but this is a bit outside my scope of knowledge for how to apply it to this scenario. If it makes any difference, this is the Protocol I am implementing. http://developer.valvesoftware.com/wiki/Source_RCON_Protocol

  Read the article

• OpenGL Performance Questions

  - by Daniel

  This subject, as with any optimisation problem, gets hit on a lot, but I just couldn't find what I (think) I want. A lot of tutorials, and even SO questions have similar tips; generally covering: Use GL face culling (the OpenGL function, not the scene logic) Only send 1 matrix to the GPU (projectionModelView combination), therefore decreasing the MVP calculations from per vertex to once per model (as it should be). Use interleaved Vertices Minimize as many GL calls as possible, batch where appropriate And possibly a few/many others. I am (for curiosity reasons) rendering 28 million triangles in my application using several vertex buffers. I have tried all the above techniques (to the best of my knowledge), and received almost no performance change. Whilst I am receiving around 40FPS in my implementation, which is by no means problematic, I am still curious as to where these optimisation 'tips' actually come into use? My CPU is idling around 20-50% during rendering, therefore I assume I am GPU bound for increasing performance. Note: I am looking into gDEBugger at the moment Cross posted at Game Development

  Read the article

• Should Python import statements always be at the top of a module?

  - by Adam J. Forster

  PEP 08 states: Imports are always put at the top of the file, just after any module comments and docstrings, and before module globals and constants. However if the class/method/function that I am importing is only used in rare cases, surely it is more efficient to do the import when it is needed? Isn't this: class SomeClass(object): def not_often_called(self) from datetime import datetime self.datetime = datetime.now() more efficient than this? from datetime import datetime class SomeClass(object): def not_often_called(self) self.datetime = datetime.now()

  Read the article

• Vector [] vs copying

  - by sak

  What is faster and/or generally better? vector<myType> myVec; int i; myType current; for( i = 0; i < 1000000; i ++ ) { current = myVec[ i ]; doSomethingWith( current ); doAlotMoreWith( current ); messAroundWith( current ); checkSomeValuesOf( current ); } or vector<myType> myVec; int i; for( i = 0; i < 1000000; i ++ ) { doSomethingWith( myVec[ i ] ); doAlotMoreWith( myVec[ i ] ); messAroundWith( myVec[ i ] ); checkSomeValuesOf( myVec[ i ] ); } I'm currently using the first solution. There are really millions of calls per second and every single bit comparison/move is performance-problematic.

  Read the article

• Python Profiling In Windows, How do you ignore Builtin Functions

  - by Tim McJilton

  I have not been capable of finding this anywhere online. I was looking to find out using a profiler how to better optimize my code, and when sorting by which functions use up the most time cumulatively, things like str(), print, and other similar widely used functions eat up much of the profile. What is the best way to profile a python program to get the user-defined functions only to see what areas of their code they can optimize? I hope that makes sense, any light you can shed on this subject would be very appreciated.

  Read the article

• How to increase query speed without using full-text search?

  - by andre matos

  This is my simple query; By searching selectnothing I'm sure I'll have no hits. SELECT nome_t FROM myTable WHERE nome_t ILIKE '%selectnothing%'; This is the EXPLAIN ANALYZE VERBOSE Seq Scan on myTable (cost=0.00..15259.04 rows=37 width=29) (actual time=2153.061..2153.061 rows=0 loops=1) Output: nome_t Filter: (nome_t ~~* '%selectnothing%'::text) Total runtime: 2153.116 ms myTable has around 350k rows and the table definition is something like: CREATE TABLE myTable ( nome_t text NOT NULL, ) I have an index on nome_t as stated below: CREATE INDEX idx_m_nome_t ON myTable USING btree (nome_t); Although this is clearly a good candidate for Fulltext search I would like to rule that option out for now. This query is meant to be run from a web application and currently it's taking around 2 seconds which is obviously too much; Is there anything I can do, like using other index methods, to improve the speed of this query?

  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

< Previous Page | 111 112 113 114 115 116 117 118 119 120 121 122  | Next Page >