Search Results

Search found 28685 results on 1148 pages for 'query performance'.

Page 328/1148 | < Previous Page | 324 325 326 327 328 329 330 331 332 333 334 335  | Next Page >

  • Join unrelated tables through a second level connected table

    - by Andy M
    Hello! I have two tables of activities on a page: Views & Comments. Views id timestamp project_id user_id page_id Comments id timestamp project_id user_id page_id comment Pages id project_id title Now pages are related to projects: Projects id account_id title I am trying to create a summary page that combines views and comments ordered by time (so that the most recent views/comments are at the beginning, grouped by projects. Also, only projects for a specific account. So the result could potentially be: Project 1 View 5 (June 20th) View 4 (June 18th) Comment 5 (June 15th) Comment 4 (June 14th) Comment 3 (June 12th) Project 3 View 3 (June 10th) View 2 (June 8th) Comment 2 (June 7th) Project 2 View 1 (June 5th) Comment 1 (June 4th) If you could help with how to do this using SQL (or even doctrine) that would be awesome. Thank you.

    Read the article

  • In Java, is there a gain in using interfaces for complex models?

    - by Gnoupi
    The title is hardly understandable, but I'm not sure how to summarize that another way. Any edit to clarify is welcome. I have been told, and recommended to use interfaces to improve performances, even in a case which doesn't especially call for the regular "interface" role. In this case, the objects are big models (in a MVC meaning), with many methods and fields. The "good use" that has been recommended to me is to create an interface, with its unique implementation. There won't be any other class implementing this interface, for sure. I have been told that this is better to do so, because it "exposes less" (or something close) to the other classes which will use methods from this class, as these objects are referring to the object from its interface (all public method from the implementation being reproduced in the interface). This seems quite strange to me, as it seems like a C++ use to me (with header files). There I see the point, but in Java? Is there really a point in making an interface for such unique implementation? I would really appreciate some clarifications on the topic, so I could justify not following such kind of behavior, and the hassle it creates from duplicating all declarations.

    Read the article

  • Stored procs breaking overnight

    - by Chad
    We are running MS SQL 2005 and we have been experiencing a very peculiar problem the past few days. I have two procs, one that creates an hourly report of data. And another that calls it, puts its results in a temp table, and does some aggregations, and returns a summary. They work fine...until the next morning. The next morning, suddenly the calling report, complains about an invalid column name. The fix, is simply a recompile of the calling proc, and all works well again. How can this happen? It's happened three nights in a row since moving these procs into production.

    Read the article

  • Query distinct list of choices for Django form with App Engine Datastore

    - by Brian
    I've been trying to figure this out for hours across a couple of days, and can not get it to work. I've been everywhere. I'll continue trying to figure it out, but was hoping for a quicker solution. I'm using App Engine datastore + Django. Using a query in a view and custom forms, I was able to get a list to the form but then I was not able to post. I have been trying to figure out how to dynamically add the choices as part of the Django form... I've tried various ways with no success. Help! Below are the two models. I'd like to get a distinct list of address_id to show in the location field in InfoForm. This fields could (and maybe should) be named the same, but I thought it'd be easier if they were named different. class Info(db.Model): user = db.UserProperty() location = db.StringProperty() info = db.StringProperty() created = db.DateTimeProperty(auto_now_add=True) modified = db.DateTimeProperty(auto_now=True) class Locations(db.Model): user = db.UserProperty() address_id = db.StringProperty() address = db.StringProperty() class InfoForm(djangoforms.ModelForm): info = forms.ChoiceField(choices=INFO_CHOICES) location = forms.ChoiceField() class Meta: model = Info exclude = ['user','created','modified']

    Read the article

  • Multi-threaded random_r is slower than single threaded version.

    - by Nixuz
    The following program is essentially the same the one described here. When I run and compile the program using two threads (NTHREADS == 2), I get the following run times: real 0m14.120s user 0m25.570s sys 0m0.050s When it is run with just one thread (NTHREADS == 1), I get run times significantly better even though it is only using one core. real 0m4.705s user 0m4.660s sys 0m0.010s My system is dual core, and I know random_r is thread safe and I am pretty sure it is non-blocking. When the same program is run without random_r and a calculation of cosines and sines is used as a replacement, the dual-threaded version runs in about 1/2 the time as expected. #include <pthread.h> #include <stdlib.h> #include <stdio.h> #define NTHREADS 2 #define PRNG_BUFSZ 8 #define ITERATIONS 1000000000 void* thread_run(void* arg) { int r1, i, totalIterations = ITERATIONS / NTHREADS; for (i = 0; i < totalIterations; i++){ random_r((struct random_data*)arg, &r1); } printf("%i\n", r1); } int main(int argc, char** argv) { struct random_data* rand_states = (struct random_data*)calloc(NTHREADS, sizeof(struct random_data)); char* rand_statebufs = (char*)calloc(NTHREADS, PRNG_BUFSZ); pthread_t* thread_ids; int t = 0; thread_ids = (pthread_t*)calloc(NTHREADS, sizeof(pthread_t)); /* create threads */ for (t = 0; t < NTHREADS; t++) { initstate_r(random(), &rand_statebufs[t], PRNG_BUFSZ, &rand_states[t]); pthread_create(&thread_ids[t], NULL, &thread_run, &rand_states[t]); } for (t = 0; t < NTHREADS; t++) { pthread_join(thread_ids[t], NULL); } free(thread_ids); free(rand_states); free(rand_statebufs); } I am confused why when generating random numbers the two threaded version performs much worse than the single threaded version, considering random_r is meant to be used in multi-threaded applications.

    Read the article

  • Oracle: delete suddenly taking a long time

    - by Damo
    Hi We have a feed process which runs every day of the year. As part of that we delete every row from a table (approx 1 million rows) every day, repopulate it using 5 different stored procedures and then commit the transaction. This is the only commit statement that we call. All of a sudden the delete has started takign about 2 hours to complete. The delete is also very simple (delete from T_PROFILE_WORK) This has worked perfectly well for the past year, but in the past week i have noticed this issue. Any help on this is greatly appreciated Thanks Damien

    Read the article

  • Does variable = null set it for garbage collection

    - by manyxcxi
    Help me settle a dispute with a coworker: Does setting a variable or collection to null in Java aid in garbage collection and reducing memory usage? If I have a long running program and each function may be iteratively called (potentially thousands of times): Does setting all the variables in it to null before returning a value to the parent function help reduce heap size/memory usage?

    Read the article

  • General question: Filesystem or database?

    - by poeschlorn
    Hey guys, i want to create a small document management system. there are several users who store their files. each file which is uploaded contains an info which user uploaded it and the document content itself. In a view there are displayed all files of ONE specific user, ordered by date. What would be better: 1) giving the documents a name or metadata(XML) which contain the date and user (and iterate through them to get the metadata) or 2) giving the files a random/unique name and store metadata in a DB? something like this: date | user | filename What would you say and why? The used programming language is java and the DB is MySQL.

    Read the article

  • Quickly or concisely determine the longest string per column in a row-based data collection

    - by ccornet
    Judging from the failure of my last inquiry, I need to calculate and preset the widths of a set of columns in a table that is being made into an Excel file. Unfortunately, the string data is stored in a row-based format, but the widths must be calculated in a column-based format. The data for the spreadsheets are generated from the following two collections: var dictFiles = l.Items.Cast<SPListItem>().GroupBy(foo => foo.GetSafeSPValue("Category")).ToDictionary(bar => bar.Key); StringDictionary dictCols = GetColumnsForItem(l.Title); Where l is an SPList whose title determines which columns are used. Each SPListItem corresponds to a row of data, which are sorted into separate worksheets based on Category (hence the dictionary). The second line is just a simple StringDictionary that has the column name (A, B, C, etc.) as a key and the corresponding SPListItme field display name as the corresponding value. So for each Category, I enumerate through dictFiles[somekey] to get all the rows in that sheet, and get the particular cell data using SPListItem.Fields[dictCols[colName]]. What I am asking is, is there a quick or concise method, for any one dictFiles[somekey], to retrieve a readout of the longest string in each column provided by dictCols? If it is impossible to get both quickness and conciseness, I can settle for either (since I always have the O(n*m) route of just enumerating the collection and updating an array whenever strCurrent.Length strLongest.Length). For example, if the goal table was the following... Item# Field1 Field2 Field3 1 Oarfish Atmosphere Pretty 2 Raven Radiation Adorable 3 Sunflower Flowers Cute I'd like a function which could cleanly take the collection of items 1, 2, and 3 and output in the correct order... Sunflower, Atmosphere, Adorable Using .NET 3.5 and C# 3.0.

    Read the article

  • If a table has two xml columns, will inserting records be a lot slower?

    - by Lieven Cardoen
    Is it a bad thing to have two xml columns in one table? + How much slower are these xml columns in terms of updating/inserting/reading data? In profiler this kind of insert normally takes 0 ms, but sometimes it goes up to 160ms: declare @p8 xml set @p8=convert(xml,N'<interactions><interaction correct="false" score="0" id="0" gapid="0" x="61" y="225"><feedback/><element id="0" position="0" elementtype="1"><asset/></element></interaction><interaction correct="false" score="0" id="1" gapid="1" x="64" y="250"><feedback/><element id="0" position="0" elementtype="1"><asset/></element></interaction><interaction correct="false" score="0" id="2" gapid="2" x="131" y="250"><feedback/><element id="0" position="0" elementtype="1"><asset/></element></interaction></interactions>') declare @p14 xml set @p14=convert(xml,N'<contentinteractions/>') exec sp_executesql N'INSERT INTO [dbo].[PackageSessionNodes]([dbo].[PackageSessionNodes].[PackageSessionId], [dbo].[PackageSessionNodes].[TreeNodeId],[dbo].[PackageSessionNodes].[Duration], [dbo].[PackageSessionNodes].[Score],[dbo].[PackageSessionNodes].[ScoreMax], [dbo].[PackageSessionNodes].[Interactions],[dbo].[PackageSessionNodes].[BrainTeaser], [dbo].[PackageSessionNodes].[DateCreated], [dbo].[PackageSessionNodes].[CompletionStatus], [dbo].[PackageSessionNodes].[ReducedScore], [dbo].[PackageSessionNodes].[ReducedScoreMax], [dbo].[PackageSessionNodes].[ContentInteractions]) VALUES (@ins_dboPackageSessionNodesPackageSessionId, @ins_dboPackageSessionNodesTreeNodeId, @ins_dboPackageSessionNodesDuration, @ins_dboPackageSessionNodesScore, @ins_dboPackageSessionNodesScoreMax, @ins_dboPackageSessionNodesInteractions, @ins_dboPackageSessionNodesBrainTeaser, @ins_dboPackageSessionNodesDateCreated, @ins_dboPackageSessionNodesCompletionStatus, @ins_dboPackageSessionNodesReducedScore, @ins_dboPackageSessionNodesReducedScoreMax, @ins_dboPackageSessionNodesContentInteractions) ; SELECT SCOPE_IDENTITY() as new_id This is the table: CREATE TABLE [dbo].[PackageSessionNodes]( [PackageSessionNodeId] [int] IDENTITY(1,1) NOT NULL, [PackageSessionId] [int] NOT NULL, [TreeNodeId] [int] NOT NULL, [Duration] [int] NULL, [Score] [float] NOT NULL, [ScoreMax] [float] NOT NULL, [Interactions] [xml] NOT NULL, [BrainTeaser] [bit] NOT NULL, [DateCreated] [datetime] NULL, [CompletionStatus] [int] NOT NULL, [ReducedScore] [float] NOT NULL, [ReducedScoreMax] [float] NOT NULL, [ContentInteractions] [xml] NOT NULL, CONSTRAINT [PK_PackageSessionNodes] PRIMARY KEY CLUSTERED ( [PackageSessionNodeId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[PackageSessionNodes] WITH CHECK ADD CONSTRAINT [FK_PackageSessionNodes_PackageSessions] FOREIGN KEY([PackageSessionId]) REFERENCES [dbo].[PackageSessions] ([PackageSessionId]) ON UPDATE CASCADE ON DELETE CASCADE GO ALTER TABLE [dbo].[PackageSessionNodes] CHECK CONSTRAINT [FK_PackageSessionNodes_PackageSessions] GO ALTER TABLE [dbo].[PackageSessionNodes] WITH CHECK ADD CONSTRAINT [FK_PackageSessionNodes_TreeNodes] FOREIGN KEY([TreeNodeId]) REFERENCES [dbo].[TreeNodes] ([TreeNodeId]) GO ALTER TABLE [dbo].[PackageSessionNodes] CHECK CONSTRAINT [FK_PackageSessionNodes_TreeNodes] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_Score] DEFAULT ((-1)) FOR [Score] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_ScoreMax] DEFAULT ((-1)) FOR [ScoreMax] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_DateCreated] DEFAULT (getdate()) FOR [DateCreated] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_ReducedScore] DEFAULT ((-1)) FOR [ReducedScore] GO ALTER TABLE [dbo].[PackageSessionNodes] ADD CONSTRAINT [DF_PackageSessionNodes_ReducedScoreMax] DEFAULT ((-1)) FOR [ReducedScoreMax] GO

    Read the article

  • Time complexity of a powerset generating function

    - by Lirik
    I'm trying to figure out the time complexity of a function that I wrote (it generates a power set for a given string): public static HashSet<string> GeneratePowerSet(string input) { HashSet<string> powerSet = new HashSet<string>(); if (string.IsNullOrEmpty(input)) return powerSet; int powSetSize = (int)Math.Pow(2.0, (double)input.Length); // Start at 1 to skip the empty string case for (int i = 1; i < powSetSize; i++) { string str = Convert.ToString(i, 2); string pset = str; for (int k = str.Length; k < input.Length; k++) { pset = "0" + pset; } string set = string.Empty; for (int j = 0; j < pset.Length; j++) { if (pset[j] == '1') { set = string.Concat(set, input[j].ToString()); } } powerSet.Add(set); } return powerSet; } So my attempt is this: let the size of the input string be n in the outer for loop, must iterate 2^n times (because the set size is 2^n). in the inner for loop, we must iterate 2*n times (at worst). 1. So Big-O would be O((2^n)*n) (since we drop the constant 2)... is that correct? And n*(2^n) is worse than n^2. if n = 4 then (4*(2^4)) = 64 (4^2) = 16 if n = 100 then (10*(2^10)) = 10240 (10^2) = 100 2. Is there a faster way to generate a power set, or is this about optimal?

    Read the article

  • java increase xmx dynamically at runtime

    - by Tomer
    Hi, I have a jvm server in my machine, now I want to have 2 apservers of mine sitting in same machine, however I want the standby one to have a really low amount of memory allocated with xmx because its passive, one the main server (active) goes down I want to allocate more memory to my passive server which is already up without restarting it (I have have them both having too much xmx - note they would consume memory at startup and I cant allow possibility of outOfMemory). So I want passive - low xmx once active goes down I want my passive to receive much more xmx. is there a way for me to achieve that. Thanks

    Read the article

  • Efficiently remove points with same slope

    - by Ram
    Hi, In one of mine applications I am dealing with graphics objects. I am using open source GPC library to clip/merge two shapes. To improve accuracy I am sampling (adding multiple points between two edges) existing shapes. But before displaying back the merged shape I need to remove all the points between two edges. But I am not able to find an efficient algorithm that will remove all points between two edges which has same slope with minimum CPU utilization. Currently all points are of type PointF Any pointer on this will be a great help.

    Read the article

  • How to speed up dumping a DataTable into an Excel worksheet?

    - by AngryHacker
    I have the following routine that dumps a DataTable into an Excel worksheet. private void RenderDataTableOnXlSheet(DataTable dt, Excel.Worksheet xlWk, string [] columnNames, string [] fieldNames) { // render the column names (e.g. headers) for (int i = 0; i < columnNames.Length; i++) xlWk.Cells[1, i + 1] = columnNames[i]; // render the data for (int i = 0; i < fieldNames.Length; i++) { for (int j = 0; j < dt.Rows.Count; j++) { xlWk.Cells[j + 2, i + 1] = dt.Rows[j][fieldNames[i]].ToString(); } } } For whatever reason, dumping DataTable of 25 columns and 400 rows takes about 10-15 seconds on my relatively modern PC. Takes even longer testers' machines. Is there anything I can do to speed up this code? Or is interop just inherently slow?

    Read the article

  • Measuring the CPU frequency scaling effect

    - by Bryan Fok
    Recently I am trying to measure the effect of the cpu scaling. Is it accurate if I use this clock to measure it? template<std::intmax_t clock_freq> struct rdtsc_clock { typedef unsigned long long rep; typedef std::ratio<1, clock_freq> period; typedef std::chrono::duration<rep, period> duration; typedef std::chrono::time_point<rdtsc_clock> time_point; static const bool is_steady = true; static time_point now() noexcept { unsigned lo, hi; asm volatile("rdtsc" : "=a" (lo), "=d" (hi)); return time_point(duration(static_cast<rep>(hi) << 32 | lo)); } }; Update: According to the comment from my another post, I believe redtsc cannot use for measure the effect of cpu frequency scaling because the counter from the redtsc does not affected by the CPU frequency, am i right?

    Read the article

  • Fast serialization/deserialization of structs

    - by user256890
    I have huge amont of geographic data represented in simple object structure consisting only structs. All of my fields are of value type. public struct Child { readonly float X; readonly float Y; readonly int myField; } public struct Parent { readonly int id; readonly int field1; readonly int field2; readonly Child[] children; } The data is chunked up nicely to small portions of Parent[]-s. Each array contains a few thousands Parent instances. I have way too much data to keep all in memory, so I need to swap these chunks to disk back and forth. (One file would result approx. 2-300KB). What would be the most efficient way of serializing/deserializing the Parent[] to a byte[] for dumpint to disk and reading back? Concerning speed, I am particularly interested in fast deserialization, write speed is not that critical. Would simple BinarySerializer good enough? Or should I hack around with StructLayout (see accepted answer)? I am not sure if that would work with array field of Parent.children. UPDATE: Response to comments - Yes, the objects are immutable (code updated) and indeed the children field is not value type. 300KB sounds not much but I have zillions of files like that, so speed does matter.

    Read the article

  • resort on a std::vector vs std::insert

    - by Abruzzo Forte e Gentile
    I have a sorted std::vector of relative small size ( from 5 to 20 elements ). I used std::vector since the data is continuous so I have speed because of cache. On a specific point I need to remove an element from this vector. I have now a doubt: which is the fastest way to remove this value between the 2 options below? setting that element to 0 and call sort to reorder: this has complexity but elements are on the same cache line. call erase that will copy ( or memcpy who knows?? ) all elements after it of 1 place ( I need to investigate the behind scense of erase ). Do you know which one is faster? I think that the same approach could be thought about inserting a new element without hitting the max capacity of the vector. Regards AFG

    Read the article

  • javascript and css loadings

    - by Mike
    I was wondering, If I have, let's say 6 javascripts includes on a page and 4-5 css includes as well on the same page, does it actually makes it optimal for the page to load if I do create one file or perhaps two and append them all together instead of having bunch of them?

    Read the article

  • How to effectively measure difference in a run-time.

    - by Knowing me knowing you
    Guys, in one of the excersises in TC++PL B.S. asks to: "Write a function that either returns a value or that throws that value based on an argument. Measure the difference in run-time between the two ways." Great pity he never explaines how to measure such things. I'm not sure if I'm suppose to write simple "time start, time end" counter or maybe there are more effective and practical ways to do it? Thanks in advance.

    Read the article

  • Can I optimize this at all?

    - by Moshe
    I'm working on an iOS app and I'm using the following code for one of my tables to return the number of rows in a particular section: return [[kSettings arrayForKey:@"views"] count]; Is there any other way to write that line of code so that it is more memory efficient? EDIT: kSettings = NSUserDefaults standardUserDefaults. Is there any way to rewrite my line of code so that whatever memory it occupies is released sooner than it is released now?

    Read the article

  • Insert problem using ADO with classic ASP

    - by Kemal Akcali
    ' Setting variables Dim con, sql_insert, data_source data_source = "project_db" sql_insert = "insert into cart ( UserID,Count,ProductName,ProductDescription,ProductPrice) values ('"&user_id&"','"&count&"','"&product_name&"','"&product_description&"','"&product_price&"')" ' Creating the Connection Object and opening the database Set con = Server.CreateObject("ADODB.Connection") con.Open data_source ' Executing the sql insertion code con.Execute sql_insert ' Done. Now Close the connection con.Close Set con = Nothing AS you can see , it is a simple code . and it worked in my local host for 5 or 6 times. but now it didn't work. What's the problem ? I think , it's about my database or memory. i setup 2 different iis in 2 different computer and they behave same... please help.. Thanks

    Read the article

  • What to have in mind when building a AJAX-based webapp

    - by Industrial
    Hi everyone, We're in the first steps of what will be a AJAX-based webapp where information and generated HTML will be sent backwards and forwards with the help of JSON/POST techniques. We're able to get the data out quickly without putting to much load on the database with the help of a cache-layer that features memcached as well as disc-based cache. Besides that - what's essential to have in mind when designing AJAX heavy webapps? Thanks a lot,

    Read the article

  • Treeview Slow in IE?!?!

    - by Mike
    I have a treeview with around 200 records that needs to be fully expanded at all times (so no loading on demand). It is inside of an update panel with the updatemode set to conditional. There are other update panels on the page as well that are set to conditional. Depending on user actions the tree may need to be rebuilt by calling databind and updating the updatepanel. Everything works fine in firefox, longest postback about 2 seconds. With IE I have to wait up to 30 seconds sometimes and the action may have nothing to do with the tree just changing a dropdown in its own updatepanel takes forever. I have considered the size of viewstate and just raw HTML generated may be causing the delay but wouldn't that effect both browsers? Anyone have anyideas what is making it so slow in IE??? Thanks!

    Read the article

  • Joining two tables (through a link), one which may yield multiple rows, together into one result.

    - by Eikern
    Lets say I've got a table listing car brands or models: Cars: Id | Brand ----------- 1 | BMW 2 | Audi 3 | Volvo And I've also got another table which links features. Link: Id | carid | featureid ----------------------- 1 | 1 | 1 2 | 1 | 2 3 | 2 | 2 4 | 3 | 1 5 | 3 | 2 6 | 3 | 3 And I've got the table listing the features. Features: Id | Feature ----------- 1 | A/C 2 | 4WD 3 | Heated seats I want to list these results on my front page like this: BMW A/C 4WD Audi 4WD Volvo A/C 4WD Heated seats What's the best/most efficient way of doing this (using PHP and MySQL)?

    Read the article

< Previous Page | 324 325 326 327 328 329 330 331 332 333 334 335  | Next Page >