Search Results

Search found 15401 results on 617 pages for 'memory optimization'.

Page 52/617 | < Previous Page | 48 49 50 51 52 53 54 55 56 57 58 59  | Next Page >

  • Should i really use integer primary IDs?

    - by arthurprs
    For example, i always generate an auto-increment field for the users table, but i also specifies an UNIQUE index on their usernames. There is situations that i first need to get the userId for a given username and then execute the desired query. Or use a JOIN in the desired query. It's 2 trips to the database or a JOIN vs. a varchar index The above is just an example There is a real performance benefit on INT over small VARCHAR indexes? Thanks in advance!

    Read the article

  • Is possible to reuse subqueries?

    - by Gothmog
    Hello, I'm having some problems trying to perform a query. I have two tables, one with elements information, and another one with records related with the elements of the first table. The idea is to get in the same row the element information plus several records information. Structure could be explain like this: table [ id, name ] [1, '1'], [2, '2'] table2 [ id, type, value ] [1, 1, '2009-12-02'] [1, 2, '2010-01-03'] [1, 4, '2010-01-03'] [2, 1, '2010-01-02'] [2, 2, '2010-01-02'] [2, 2, '2010-01-03'] [2, 3, '2010-01-07'] [2, 4, '2010-01-07'] And this is want I would like to achieve: result [id, name, Column1, Column2, Column3, Column4] [1, '1', '2009-12-02', '2010-01-03', , '2010-01-03'] [2, '2', '2010-01-02', '2010-01-02', '2010-01-07', '2010-01-07'] The following query gets the proper result, but it seems to me extremely inefficient, having to iterate table2 for each column. Would be possible in anyway to do a subquery and reuse it? SELECT a.id, a.name, (select min(value) from table2 t where t.id = subquery.id and t.type = 1 group by t.type) as Column1, (select min(value) from table2 t where t.id = subquery.id and t.type = 2 group by t.type) as Column2, (select min(value) from table2 t where t.id = subquery.id and t.type = 3 group by t.type) as Column3, (select min(value) from table2 t where t.id = subquery.id and t.type = 4 group by t.type) as Column4 FROM (SELECT distinct id FROM table2 t WHERE (t.type in (1, 2, 3, 4)) AND t.value between '2010-01-01' and '2010-01-07') as subquery LEFT JOIN table a ON a.id = subquery.id

    Read the article

  • Write a compiler for a language that looks ahead and multiple files?

    - by acidzombie24
    In my language I can use a class variable in my method when the definition appears below the method. It can also call methods below my method and etc. There are no 'headers'. Take this C# example. class A { public void callMethods() { print(); B b; b.notYetSeen(); public void print() { Console.Write("v = {0}", v); } int v=9; } class B { public void notYetSeen() { Console.Write("notYetSeen()\n"); } } How should I compile that? what i was thinking is: pass1: convert everything to an AST pass2: go through all classes and build a list of define classes/variable/etc pass3: go through code and check if there's any errors such as undefined variable, wrong use etc and create my output But it seems like for this to work I have to do pass 1 and 2 for ALL files before doing pass3. Also it feels like a lot of work to do until I find a syntax error (other than the obvious that can be done at parse time such as forgetting to close a brace or writing 0xLETTERS instead of a hex value). My gut says there is some other way. Note: I am using bison/flex to generate my compiler.

    Read the article

  • .Net Memory limit

    - by Prashant
    I have a .Net application running on a 32 bit box. The application is a windows service. It consistently hovers around 600-800 MB range. Is this a problem. If an application crosses 1 GB, is it a memory issue ?

    Read the article

  • Optimizing mathematics on arrays of floats in Ada 95 with GNATC

    - by mat_geek
    Consider the bellow code. This code is supposed to be processing data at a fixed rate, in one second batches, It is part of an overal system and can't take up too much time. When running over 100 lots of 1 seconds worth of data the program takes 35 seconds; or 35%. How do I improce the code to get the processing time down to a minimum? The code will be running on an Intel Pentium-M which is a P3 with SSE2. package FF is new Ada.Numerics.Generic_Elementary_Functions(Float); N : constant Integer := 820; type A is array(1 .. N) of Float; type A3 is array(1 .. 3) of A; procedure F(state : in out A3; result : out A3; l : in A; r : in A) is s : Float; t : Float; begin for i in 1 .. N loop t := l(i) + r(i); t := t / 2.0; state(1)(i) := t; state(2)(i) := t * 0.25 + state(2)(i) * 0.75; state(3)(i) := t * 1.0 /64.0 + state(2)(i) * 63.0 /64.0; for r in 1 .. 3 loop s := state(r)(i); t := FF."**"(s, 6.0) + 14.0; if t > MAX then t := MAX; elsif t < MIN then t := MIN; end if; result(r)(i) := FF.Log(t, 2.0); end loop; end loop; end;

    Read the article

  • XCode and Instruments for memory leaks

    - by coure06
    I have tested my iphone app using XCode and instrument. I am watching the memory allocation tables, its showing me that every things is increasing i.e Bytes, Live Bytes and so on. What does it means? Am i not deallocating the objects? Can i find which objects are not deallocating using instruments?

    Read the article

  • How to configure a Firebird Database to run in memory

    - by Robert
    I'm running a software called Fishbowl inventory and it is running on a firebird database (Windows server 2003) at this time the fishbowl software is running extremely slow when more then one user accesses the software. I'm thinking I maybe able to speed up the application by forcing the database to run "In Memory". However I can not find documentation on how to do this. Any help would be greatly appreciated. Thank you in advance. Robert

    Read the article

  • Postgres query optmization

    - by hdx
    Hey guys, trying to optimize this query to solve a duplicate user issue: SELECT userid, 'ismaster' AS name, 'false' AS propvalue FROM user WHERE userid NOT IN (SELECT userid FROM userprop WHERE name = 'ismaster'); The problem is that the select after the NOT IN is 120.000 records and it's taking forever. Any suggestion?

    Read the article

  • dynamic memory allocation in C

    - by avanish
    int main() { int p; scanf("%d",&p); fun() { int arr[p]; //isn't this similar to dynamic memory allocation?? } } //if not then what other objective is achieved using malloc and calloc?? //Someone please throw some light :-)

    Read the article

  • Optimizing mathematics on arrays of floats in Ada 95 with GNAT

    - by mat_geek
    Consider the bellow code. This code is supposed to be processing data at a fixed rate, in one second batches, It is part of an overal system and can't take up too much time. When running over 100 lots of 1 seconds worth of data the program takes 35 seconds (or 35%), executing this function in a loop. The test loop is timed specifically with Ada.RealTime. The data is pregenerated so the majority of the execution time is definatetly in this loop. How do I improce the code to get the processing time down to a minimum? The code will be running on an Intel Pentium-M which is a P3 with SSE2. package FF is new Ada.Numerics.Generic_Elementary_Functions(Float); N : constant Integer := 820; type A is array(1 .. N) of Float; type A3 is array(1 .. 3) of A; procedure F(state : in out A3; result : out A3; l : in A; r : in A) is s : Float; t : Float; begin for i in 1 .. N loop t := l(i) + r(i); t := t / 2.0; state(1)(i) := t; state(2)(i) := t * 0.25 + state(2)(i) * 0.75; state(3)(i) := t * 1.0 /64.0 + state(2)(i) * 63.0 /64.0; for r in 1 .. 3 loop s := state(r)(i); t := FF."**"(s, 6.0) + 14.0; if t > MAX then t := MAX; elsif t < MIN then t := MIN; end if; result(r)(i) := FF.Log(t, 2.0); end loop; end loop; end; psuedocode for testing create two arrays of 80 random A3 arrays, called ls and rs; init the state and result A3 array record the realtime time now, called last for i in 1 .. 100 loop for j in 1 .. 80 loop F(state, result, ls(j), rs(j)); end loop; end loop; record the realtime time now, called curr output the duration between curr and last

    Read the article

  • Optimizing MySql query to avoid using "Using filesort"

    - by usef_ksa
    I need your help to optimize the query to avoid using "Using filesort".The job of the query is to select all the articles that belongs to specific tag. The query is: "select title from tag,article where tag='Riyad' AND tag.article_id=article.id order by tag.article_id". the tables structure are the following: Tag table CREATE TABLE `tag` ( `tag` VARCHAR( 30 ) NOT NULL , `article_id` INT NOT NULL , INDEX ( `tag` ) ) ENGINE = MYISAM ; Article table CREATE TABLE `article` ( `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY , `title` VARCHAR( 60 ) NOT NULL ) ENGINE = MYISAM Sample data INSERT INTO `article` VALUES (1, 'About Riyad'); INSERT INTO `article` VALUES (2, 'About Newyork'); INSERT INTO `article` VALUES (3, 'About Paris'); INSERT INTO `article` VALUES (4, 'About London'); INSERT INTO `tag` VALUES ('Riyad', 1); INSERT INTO `tag` VALUES ('Saudia', 1); INSERT INTO `tag` VALUES ('Newyork', 2); INSERT INTO `tag` VALUES ('USA', 2); INSERT INTO `tag` VALUES ('Paris', 3); INSERT INTO `tag` VALUES ('France', 3);

    Read the article

  • expat parser: memory consumption

    - by sameer karjatkar
    Hi, I am using expat parser to parse an XML file of around 15 GB . The problem is it throws an "Out of Memory" error and the program aborts . I want to know has any body faced a similar issue with the expat parser or is it a known bug and has been rectified in later versions ?

    Read the article

  • Android: Memory leak due to AsyncTask

    - by Manu
    Hello, I'm stuck with a memory leak that I cannot fix. I identified where it occurs, using the MemoryAnalizer but I vainly struggle to get rid of it. Here is the code: public class MyActivity extends Activity implements SurfaceHolder.Callback { ... Camera.PictureCallback mPictureCallbackJpeg = new Camera.PictureCallback() { public void onPictureTaken(byte[] data, Camera c) { try { // log the action Log.e(getClass().getSimpleName(), "PICTURE CALLBACK JPEG: data.length = " + data); // Show the ProgressDialog on this thread pd = ProgressDialog.show(MyActivity.this, "", "Préparation", true, false); // Start a new thread that will manage the capture new ManageCaptureTask().execute(data, c); } catch(Exception e){ AlertDialog.Builder dialog = new AlertDialog.Builder(MyActivity.this); ... dialog.create().show(); } } class ManageCaptureTask extends AsyncTask<Object, Void, Boolean> { protected Boolean doInBackground(Object... args) { Boolean isSuccess = false; // initialize the bitmap before the capture ((myApp) getApplication()).setBitmapX(null); try{ // Check if it is a real device or an emulator TelephonyManager telmgr = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE); String deviceID = telmgr.getDeviceId(); boolean isEmulator = "000000000000000".equalsIgnoreCase(deviceID); // get the bitmap if (isEmulator) { ((myApp) getApplication()).setBitmapX(BitmapFactory.decodeFile(imageFileName)); } else { ((myApp) getApplication()).setBitmapX(BitmapFactory.decodeByteArray((byte[]) args[0], 0, ((byte[])args[0]).length)); } ((myApp) getApplication()).setImageForDB(ImageTools.resizeBmp(((myApp) getApplication()).getBmp())); // convert the bitmap into a grayscale image and display it in the preview ((myApp) getApplication()).setImage(makeGrayScale()); isSuccess = true; } catch (Exception connEx){ errorMessageFromBkgndThread = getString(R.string.errcapture); } return isSuccess; } protected void onPostExecute(Boolean result) { // Pass the result data back to the main activity if (MyActivity.this.pd != null) { MyActivity.this.pd.dismiss(); } if (result){ ((ImageView) findViewById(R.id.apercu)).setImageBitmap(((myApp) getApplication()).getBmp()); ((myApp) getApplication()).setBitmapX(null); } else{ // there was an error ErrAlert(); } } } }; private void ErrAlert(){ // notify the user about the error AlertDialog.Builder dialog = new AlertDialog.Builder(this); ... dialog.create().show(); } } MemoryAnalyzer indicated the memory leak at: ((myApp) getApplication()).setBitmapX(BitmapFactory.decodeByteArray((byte[]) args[0], 0, ((byte[])args[0]).length)); I am grateful for any suggestion, thank you in advance.

    Read the article

  • How can I make this Java code run faster?

    - by Martin Wiboe
    Hello all, I am trying to make a Java port of a simple feed-forward neural network. This obviously involves lots of numeric calculations, so I am trying to optimize my central loop as much as possible. The results should be correct within the limits of the float data type. My current code looks as follows (error handling & initialization removed): /** * Simple implementation of a feedforward neural network. The network supports * including a bias neuron with a constant output of 1.0 and weighted synapses * to hidden and output layers. * * @author Martin Wiboe */ public class FeedForwardNetwork { private final int outputNeurons; // No of neurons in output layer private final int inputNeurons; // No of neurons in input layer private int largestLayerNeurons; // No of neurons in largest layer private final int numberLayers; // No of layers private final int[] neuronCounts; // Neuron count in each layer, 0 is input // layer. private final float[][][] fWeights; // Weights between neurons. // fWeight[fromLayer][fromNeuron][toNeuron] // is the weight from fromNeuron in // fromLayer to toNeuron in layer // fromLayer+1. private float[][] neuronOutput; // Temporary storage of output from previous layer public float[] compute(float[] input) { // Copy input values to input layer output for (int i = 0; i < inputNeurons; i++) { neuronOutput[0][i] = input[i]; } // Loop through layers for (int layer = 1; layer < numberLayers; layer++) { // Loop over neurons in the layer and determine weighted input sum for (int neuron = 0; neuron < neuronCounts[layer]; neuron++) { // Bias neuron is the last neuron in the previous layer int biasNeuron = neuronCounts[layer - 1]; // Get weighted input from bias neuron - output is always 1.0 float activation = 1.0F * fWeights[layer - 1][biasNeuron][neuron]; // Get weighted inputs from rest of neurons in previous layer for (int inputNeuron = 0; inputNeuron < biasNeuron; inputNeuron++) { activation += neuronOutput[layer-1][inputNeuron] * fWeights[layer - 1][inputNeuron][neuron]; } // Store neuron output for next round of computation neuronOutput[layer][neuron] = sigmoid(activation); } } // Return output from network = output from last layer float[] result = new float[outputNeurons]; for (int i = 0; i < outputNeurons; i++) result[i] = neuronOutput[numberLayers - 1][i]; return result; } private final static float sigmoid(final float input) { return (float) (1.0F / (1.0F + Math.exp(-1.0F * input))); } } I am running the JVM with the -server option, and as of now my code is between 25% and 50% slower than similar C code. What can I do to improve this situation? Thank you, Martin Wiboe

    Read the article

  • Optimizing ROW_NUMBER() in SQL Server

    - by BlueRaja
    We have a number of machines which record data into a database at sporadic intervals. For each record, I'd like to obtain the time period between this recording and the previous recording. I can do this using ROW_NUMBER as follows: WITH TempTable AS ( SELECT *, ROW_NUMBER() OVER (PARTITION BY Machine_ID ORDER BY Date_Time) AS Ordering FROM dbo.DataTable ) SELECT [Current].*, Previous.Date_Time AS PreviousDateTime FROM TempTable AS [Current] INNER JOIN TempTable AS Previous ON [Current].Machine_ID = Previous.Machine_ID AND Previous.Ordering = [Current].Ordering + 1 The problem is, it goes really slow (several minutes on a table with about 10k entries) - I tried creating separate indicies on Machine_ID and Date_Time, and a single joined-index, but nothing helps. Is there anyway to rewrite this query to go faster?

    Read the article

  • What is a data structure for quickly finding non-empty intersections of a list of sets?

    - by Andrey Fedorov
    I have a set of N items, which are sets of integers, let's assume it's ordered and call it I[1..N]. Given a candidate set, I need to find the subset of I which have non-empty intersections with the candidate. So, for example, if: I = [{1,2}, {2,3}, {4,5}] I'm looking to define valid_items(items, candidate), such that: valid_items(I, {1}) == {1} valid_items(I, {2}) == {1, 2} valid_items(I, {3,4}) == {2, 3} I'm trying to optimize for one given set I and a variable candidate sets. Currently I am doing this by caching items_containing[n] = {the sets which contain n}. In the above example, that would be: items_containing = [{}, {1}, {1,2}, {2}, {3}, {3}] That is, 0 is contained in no items, 1 is contained in item 1, 2 is contained in itmes 1 and 2, 2 is contained in item 2, 3 is contained in item 2, and 4 and 5 are contained in item 3. That way, I can define valid_items(I, candidate) = union(items_containing[n] for n in candidate). Is there any more efficient data structure (of a reasonable size) for caching the result of this union? The obvious example of space 2^N is not acceptable, but N or N*log(N) would be.

    Read the article

  • Delphi memory management design strategies : Object or Interface ?

    - by Pierre-Jean Coudert
    Regarding Delphi memory management, what are your design strategies ? What are the use cases where you prefer to create and release Objects manually ? What are the uses cases where Interfaces, InterfacedObjects, and their reference counting mechanism will be prefered ? Do you have identified some traps or difficulties with reference counted objects ? Thanks for sharing your experience here.

    Read the article

  • Using * in SELECT Query

    - by libregeek
    I am currently porting an application written in MySQL3 and PHP4 to MySQL5 and PHP5. On analysis I found several SQL queries which uses "select * from tablename" even if only one column(field) is processed in PHP. The table has almost 60 columns and it has a primary key. In most cases, the only column used is id which is the primary key. Will there be any performance boost if I use queries in which the column names are explicitly mentioned instead of * ? (In this application there is only one method which we need all the columns and all other methods return only a subset of the columns)

    Read the article

  • Please help optimizing a long running query (left outer join, with 2 subqueries)

    - by 46and2
    Hi all. The query I need help with is: SELECT d.bn, d.4700, d.4500, ... , p.`Activity Description` FROM ( SELECT temp.bn, temp.4700, temp.4500, .... FROM `tdata` temp GROUP BY temp.bn HAVING (COUNT(temp.bn) = 1) ) d LEFT OUTER JOIN ( SELECT temp2.bn, max(temp2.FPE) AS max_fpe, temp2.`Activity Description` FROM `pdata` temp2 GROUP BY temp2.bn ) p ON p.bn = d.bn; The ... represents other fields that aren't really important to solving this problem. The issue is on the the second subquery - it is not using the index I have created and I am not sure why, it seems to be because of the way TEXT fields are handled. The first subquery uses the index I have created and runs quite snappy, however an explain on the second shows a 'Using temporary; Using filesort'. Please see the indexes I have created in the below table create statements. Can anyone help me optimize this? By way of quick explanation the first subquery is meant to only select records that have unique bn's, the second, while it looks a bit wacky (with the max function there which is not being used in the result set) is making sure that only one record from the right part of the join is included in the result set. My table create statements are CREATE TABLE `tdata` ( `BN` varchar(15) DEFAULT NULL, `4000` varchar(3) DEFAULT NULL, `5800` varchar(3) DEFAULT NULL, .... KEY `BN` (`BN`), KEY `idx_t3010`(`BN`,`4700`,`4500`,`4510`,`4520`,`4530`,`4570`,`4950`,`5000`,`5010`,`5020`,`5050`,`5060`,`5070`,`5100`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 CREATE TABLE `pdata` ( `BN` varchar(15) DEFAULT NULL, `FPE` datetime DEFAULT NULL, `Activity Description` text, .... KEY `BN` (`BN`), KEY `idx_programs_2009` (`BN`,`FPE`,`Activity Description`(100)) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 Thanks!

    Read the article

< Previous Page | 48 49 50 51 52 53 54 55 56 57 58 59  | Next Page >