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  • TCP Server Memory management: #Connections Vs. #Requests

    - by Andrew
    Given that, there is no theoretical limit to number of concurrent TCP connections a Windows 2008 server can handle. Only thing will happen is, with each connection there will be memory consumption in server. Unfortunately, memory is not unlimited (and I want to utilize only physical memory). For example, lets say we've 2GB server memory. Now there are two extreme cases: Case 1: If we've allocated 64KB buffer for each connection (only to receive incoming request), then 32768 connections can consume all the 2GB of memory. This will not leave any memory to queue/process incoming requests from those connections. Case 2: On the other hand, lets say a single (or very few) connections continuously keeps sending request buffers (for example, video streaming from one connection to other) and server cannot process them within time, those buffers will get piled up in server and eventually will occupy most of the servers memory. And it will not leave any memory for new connection thereafter. This is the real dilemma in server design bugging me badly for last many days. If I can decide on max size of request buffer per connection and max number of requests to allow in queue per connection. Then, based on available server memory, it will then automatically set limit on max number of concurrent connections. How to decide on these limits to achieve best performance and throughput? I am just looking for perfect utilization of server resources. Are there any standard guidelines or empirical data available with someone who can share with me please.

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  • Windows Displays Double the Actual Installed Physical Memory

    - by Andrew Barber
    I have a server I've installed Windows Web 2008 R2 on, which is reporting that I have double the physical memory installed as is actually the case. In msinfo32 "Installed Physical Memory" shows as 2x what ever the actual installed amount is, though "Total Physical Memory" shows the correct amount. The "System" info window shows installed memory as 2x, with the correct amount in parenthesis listed as the "usable" amount). This server mistakenly had Windows Web 2008 (32-bit) installed on it just previously, and that OS also reported the same faulty information as Win2K8R2 is reporting. BIOS reports the correct amount, memtest was run on this server before installation, and a previous Windows 2000 instance installed on this system also reported the correct amount, as I recall. Server operation seems to be fine as well (it's only trying to use the correct amount of memory). The server is a generic pizzabox running on a SuperMicro X6DVL-EG with dual Xeon-3.2's. Memory installed are 4 matching mt18vddf12872g-335c3 sticks (1GB pc2700 DDR ECC REG cl2.5) This behavior occurs whether two or all four are installed. So, has anyone seen something like this before? Have any idea about what's causing it, and how I should be concerned about it? Everything else seems good so far, and I'll be upgrading the memory before putting the server into service, but I don't want to spend too much time/money/effort on the server if it's got something odd going wrong here. UPDATE: There was a question I ran into regarding memory sparing in the BIOS and a possible (buggy) effect thereof; however, flipping that bit back and forth in the BIOS revealed that isn't the issue. Still flummoxed a bit about this one, though I still have seen no negative impacts. Post-Answer Update (January 13, 2011): Upgrading the system with new, larger memory has fixed this issue.

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  • Animating Tile with Blitting taking up Memory.

    - by Kid
    I am trying to animate a specific tile in my 2d Array, using blitting. The animation consists of three different 16x16 sprites in a tilesheet. Now that works perfect with the code below. BUT it's causing memory leakage. Every second the FlashPlayer is taking up +140 kb more in memory. What part of the following code could possibly cause the leak: //The variable Rectangle finds where on the 2d array we should clear the pixels //Fillrect follows up by setting alpha 0 at that spot before we copy in nxt Sprite //Tiletype is a variable that holds what kind of tile the next tile in animation is //(from tileSheet) //drawTile() gets Sprite from tilesheet and copyPixels it into right position on canvas public function animateSprite():void{ tileGround.bitmapData.lock(); if(anmArray[0].tileType > 42){ anmArray[0].tileType = 40; frameCount = 0; } var rect:Rectangle = new Rectangle(anmArray[0].xtile * ts, anmArray[0].ytile * ts, ts, ts); tileGround.bitmapData.fillRect(rect, 0); anmArray[0].tileType = 40 + frameCount; drawTile(anmArray[0].tileType, anmArray[0].xtile, anmArray[0].ytile); frameCount++; tileGround.bitmapData.unlock(); } public function drawTile(spriteType:int, xt:int, yt:int):void{ var tileSprite:Bitmap = getImageFromSheet(spriteType, ts); var rec:Rectangle = new Rectangle(0, 0, ts, ts); var pt:Point = new Point(xt * ts, yt * ts); tileGround.bitmapData.copyPixels(tileSprite.bitmapData, rec, pt, null, null, true); } public function getImageFromSheet(spriteType:int, size:int):Bitmap{ var sheetColumns:int = tSheet.width/ts; var col:int = spriteType % sheetColumns; var row:int = Math.floor(spriteType/sheetColumns); var rec:Rectangle = new Rectangle(col * ts, row * ts, size, size); var pt:Point = new Point(0,0); var correctTile:Bitmap = new Bitmap(new BitmapData(size, size, false, 0)); correctTile.bitmapData.copyPixels(tSheet, rec, pt, null, null, true); return correctTile; }

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  • chrome memory and cpu footprint

    - by nmizar
    I've searched the forums for an answer but I couldn't find quite the answer I was looking for [1] , so I thought I it could as well be of interest to more people around here. I carry out a big part of my job on the browser (or for the browser, if you want to put it that way). I tend to use Chrome, because it's got natively many of the newest features that I need (DevTools stuff, mainly but not only). BTW, I'm usually running the last available Chrome version/build on a desktop Vaio with 4GB RAM and dual core CPU and Ubuntu 12.04 as distro and Gnome as window manager. So, I was curious about a) why does Chrome spawn so many threads even opening only three of four tabs and b) is there any way to allocate more memory to Chrome to prevent its performance from degrading? Thanks in advance, Nacho PS [1] I found threads about Chrome freezing or running out of memory but not about the reasons for this being so or for avoiding it to happen. PPS Of course, I could always buy a newer and more capable machine and that is exactly what I'm trying to evaluate: is this a question of outdated hardware or the problem will keep appearing on any (decently but not hugely sized) machine?

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  • opengl memory issue - quite strange.

    - by user4707
    Hello, I have heard that textures consumes lot of memory but I am surprised how much.... I have 7 textures 1024 16 bit each. And while I will run my app it consumes 57MB of memory. I think that this is "a bit" too much. I am writing 2D application (no cocos or other framework) Strange is that while I will compile my app with disabled rendering methods: glDrawArrays than It uses only 27MB.... which is about 30MB less... Do you have any Idea why? I am creating textures before rendering of course: rendering looks like this: [EAGLContext setCurrentContext:context]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer); glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); TeksturaObrazek *obrazek_klaw =[[AppDirector sharedAppDirector] obrazek_klaw]; glBindTexture(GL_TEXTURE_2D, [[obrazek_klaw image_texture] name] ); glVertexPointer(2, GL_FLOAT, 0,vertex1); glTexCoordPointer(2, GL_FLOAT, 0, vertex2); glColor4f(1,1,1,alpha); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisable(GL_BLEND); glDisable(GL_TEXTURE_2D); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glPopMatrix(); [context presentRenderbuffer:GL_RENDERBUFFER_OES]; It looks like standard routine... I have spent about 2 days looking for for answer and I still have no clue.

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  • Cocoa Memory Usage

    - by user288024
    I'm trying to track down some peculiar memory behavior in my Cocoa desktop app. My app does a lot of image processing using NSImage and uploads those images to a website over HTTP using NSURLConnection. After uploading several hundred images (some very large), when I run Instrument I get no leaks. I've also run through MallocDebug and get no leaks. When I dig into object allocations using Instrument I get output like this: GeneralBlock-9437184, Net Bytes 9437184, # Net 1 GeneralBlock-192512, Net Bytes 2695168, # Net 14 and etc., for smaller sizes. When I look at these in detail, they're marked as being owned by 'Foundation' and created via NSConcreteMutableData initWithCapacity. During HTTP upload I'm creating a post body using NSMutableData, so I'm guessing these are buffers Cocoa is caching for me when I create the NSMutableData objects. Is there a way to force Cocoa to free these? I'm 90% positive I'm releasing correctly (and Instruments and MallocDebug seem to confirm this), but I think Cocoa is keeping these around for perf reasons since I'm allocating so many MSMutableData buffers.

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  • c# memory allocation and deallocation patterns

    - by Neal
    Since C# uses Garbage Collection. When is it necessary to use .Dispose to free the memory? I realize there are a few situations so I'll try to list the ones I can think of. If I close a Form that contains GUI type object, are those objects dereferenced and therefore will be collected? If I create a local object using new should I .Dispose of it before the method exits or just let the GC take care of it? What is good practice in this case? Are there any times in which forcing a GC is understandable? Are events collected by the GC when it's object is collected?

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  • memory usage in iOS

    - by varun
    My app has a simple UI interface having simple buttons, date picker, picker view, table view, action sheet, toolbar, alert boxes etc. No images, no network access. Just plain simple UI. It accesses SQLite database a lot. ARC option is enabled. I have many questions to ask: In .h files, I am defining IBOutlets like @property(nonatomic, retain) IBOutlet UIButton *bt; Where do i need to do bt=nil? in didReceiveMemoryWarning or viewDidLoad Live Bytes in Instruments tool is 4-5MB. Is it enough or I need to reduce memory usage? If so, how can I do so? Please mention few important points. Also, what all need to be added to the following methods? applicationDidReceiveMemoryWarning UIApplicationDidReceiveMemoryWarningNotification

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  • How to reduce memory consumption an AWS EC2 t1.micro instance (free tier) ubuntu server 14.04 LTS EBS

    - by CMPSoares
    Hi I'm working on my bachelor thesis and for that I need to host a node.js web application on AWS, in order to avoid costs I'm using a t1.micro instance with 30GB disk space (from what I know it's the maximum I get in the free tier) which is barely used. But instead I have problems with memory consumption, it's using all of it. I tried the approach of creating a virtual swap area as mentioned at Why don't EC2 ubuntu images have swap? with these commands: sudo dd if=/dev/zero of=/var/swapfile bs=1M count=2048 && sudo chmod 600 /var/swapfile && sudo mkswap /var/swapfile && echo /var/swapfile none swap defaults 0 0 | sudo tee -a /etc/fstab && sudo swapon -a But this swap area isn't used somehow. Is something missing in this approach or is there another process of reducing the memory consumption in these type of AWS instances? Bottom-line: This originates server freezes and crashes and that's what I want to stop either by using the swap, reducing memory usage or both.

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  • Apparent leak in Mozilla Firefox

    - by LeopardSkinPillBoxHat
    I use Mozilla Firefox 3.6 all day, opening and closing tabs quite regularly. I am noticing over time that the firefox.exe process size keeps growing and growing over time. Initially I put this down to memory fragmentation caused by opening and closing tabs, but now I am suspecting that there is a memory leak in one of the add-ons that I have installed. The problem I am seeing is that when the process size gets to about 1.5GB in the "Mem Usage" stat in Task Manager (and it gets there quite regularly), Firefox freezes up. Does anyone have any ideas about how I could diagnose whether: Any of the add-ons are leaking memory? Something else is causing this problem?

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  • What could be causing SVCHost to leak handles?

    - by Goz
    I have a problem that has been causing me all sorts of grief recently. SVCHost appears to be leaking resources all over the shop. This is the SVCHost run with the arguments "-k netsvcs". At the moment it is sitting at around 5,700 Handles being used. Before I rebooted the machine it was sitting at around 33,000 handles! This higher number has been causing me large problems as my software, thus, fails to obtain the handles it needs (The software tries to create around 2000 handles). I'm totally at a loss as to what is going wrong. IF anyone could help me stop this happening it would be much appreciated. I'm running on XP with SP3. Edit: I tracked this problem down to the WMI system. I'm not sure why or how the problem was occurring. Basically I used "sc change" to move it into its own process and suddenly everything seems to be fine. I'm not entirely sure what is going on ...

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  • Tomcat memory usage grows until crash with no GC run

    - by Phil
    I'm administrating a server running Tomcat that is getting a lot of traffic lately. If I monitor memory usage in Task Manager I can see the memory usage growing and eventually tomcat crashes around the 1GB mark. Here's the memory relevent bits I've set in Tomcat Properties (this is a Windows Server): Intial memory pool: 1024 MB Maximum memory pool: 1024 MB -XX:MaxPermSize=256M The weird thing is since these problems arose I've deployed Lambda Probe to the Tomcat instance and the memory usage values I see there are much lower, for example Task Manager might show 467MB used while the "Total" used in Probe is 212 MB. Also, the Maximum Total listed in Probe is 1.29GB, when I would have expected 1GB, the maximum memory set above. If I force the garbage collector to run using Probe, I can keep Tomcat from crashing for a while (indefinitely, AFAIK). So why doesn't the GC run automatically and stop Tomcat from crashing? Thanks.

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  • SQL 2008 Memory Usage

    - by Danilo Brambilla
    I have a SQL Server 2008 (ver 10.0.1600) running on a Windows Server 2008 R2 Enterprise server with 8 GB of physical ram. If I open Task Manager I can see on 'Physical Memory' section of 'Performance' tab that only 340 MB are Available of 8191 Total, but I can't see any process using such amount of memory. Please note SQL Server is memory limited to 6GB (Maximum Server Memory = 6000). If I open Sysinternals Process Explorer, I can see sqlsrvr.exe process has: Private Bytes: 227.000 K Working Set: 140.000 K Virtual Size: 8.762.000 K What does this means? Is there any way to free up this memory for other process? Why Virtual Size figure as allocated memory? I thought that Virtual Size was 'reserved memory' only.

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  • SQL 2008 Memory Usage

    - by Danilo Brambilla
    I have a SQL Server 2008 (ver 10.0.1600) running on a Windows Server 2008 R2 Enterprise server with 8 GB of physical ram. If I open Task Manager I can see on 'Physical Memory' section of 'Performance' tab that only 340 MB are Available of 8191 Total, but I can't see any process using such amount of memory. Please note SQL Server is memory limited to 6GB (Maximum Server Memory = 6000). If I open Sysinternals Process Explorer, I can see sqlsrvr.exe process has: Private Bytes: 227.000 K Working Set: 140.000 K Virtual Size: 8.762.000 K What does this means? Is there any way to free up this memory for other process? Why Virtual Size figure as allocated memory? I thought that Virtual Size was 'reserved memory' only.

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  • HP DL160 G6 memory PC3-10600R vs PC3-10600E

    - by Jeremy Hajek
    I am using a HP DL 160 G6 server that according to specs takes PC3 Registered or Unbuffered. When I combine the two types of memory below the system will not POST. When I use just the first type of memory listed the system will POST. I have two pieces of HP memory that came with the server labeled PC3-10600E-9-10-E0 and then I have some Crucial memory labeled PC3-10600R-9-10-B0 I wager that the R means Registered memory and the E means ECC - then shouldn't the crucial memory boot with the system according to the HP specs? Or does the E mean it is Unbuffered and therefore I shouldn't mix and match as according to this HP memory config doc?

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  • Motherboard not recognizing memory anymore

    - by root
    I bought some new RAM and installed it on my motherboard. But, the BIOS would not post. There's an LED on my motherboard that shows error codes, and it showed the error: No usable memory detected. So, I removed the new memory and reinstalled the old memory, thus restoring the computer back to its original configuration. But, the BIOS still would not post, still giving the error: No usable memory detected. I've ensured that the memory and power headers are seated properly. I've tried all possible combinations of memory slots, and I've also reset the CMOS, but the error remains the same. The computer was working fine before I tried upgrading the memory, and I originally assembled the computer myself. What are some possible causes of this problem?

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  • Out of memory when creating a lot of objects C#

    - by Bas
    I'm processing 1 million records in my application, which I retrieve from a MySQL database. To do so I'm using Linq to get the records and use .Skip() and .Take() to process 250 records at a time. For each retrieved record I need to create 0 to 4 Items, which I then add to the database. So the average amount of total Items that has to be created is around 2 million. while (objects.Count != 0) { using (dataContext = new LinqToSqlContext(new DataContext())) { foreach (Object objectRecord in objects) { // Create a list of 0 - 4 Random Items and add each Item to the Object for (int i = 0; i < Random.Next(0, 4); i++) { Item item = new Item(); item.Id = Guid.NewGuid(); item.Object = objectRecord.Id; item.Created = DateTime.Now; item.Changed = DateTime.Now; dataContext.InsertOnSubmit(item); } } dataContext.SubmitChanges(); } amountToSkip += 250; objects = objectCollection.Skip(amountToSkip).Take(250).ToList(); } Now the problem arises when creating the Items. When running the application (and not even using dataContext) the memory increases consistently. It's like the items are never getting disposed. Does anyone notice what I'm doing wrong? Thanks in advance!

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  • Out-of-memory algorithms for addressing large arrays

    - by reve_etrange
    I am trying to deal with a very large dataset. I have k = ~4200 matrices (varying sizes) which must be compared combinatorially, skipping non-unique and self comparisons. Each of k(k-1)/2 comparisons produces a matrix, which must be indexed against its parents (i.e. can find out where it came from). The convenient way to do this is to (triangularly) fill a k-by-k cell array with the result of each comparison. These are ~100 X ~100 matrices, on average. Using single precision floats, it works out to 400 GB overall. I need to 1) generate the cell array or pieces of it without trying to place the whole thing in memory and 2) access its elements (and their elements) in like fashion. My attempts have been inefficient due to reliance on MATLAB's eval() as well as save and clear occurring in loops. for i=1:k [~,m] = size(data{i}); cur_var = ['H' int2str(i)]; %# if i == 1; save('FileName'); end; %# If using a single MAT file and need to create it. eval([cur_var ' = cell(1,k-i);']); for j=i+1:k [~,n] = size(data{j}); eval([cur_var '{i,j} = zeros(m,n,''single'');']); eval([cur_var '{i,j} = compare(data{i},data{j});']); end save(cur_var,cur_var); %# Add '-append' when using a single MAT file. clear(cur_var); end The other thing I have done is to perform the split when mod((i+j-1)/2,max(factor(k(k-1)/2))) == 0. This divides the result into the largest number of same-size pieces, which seems logical. The indexing is a little more complicated, but not too bad because a linear index could be used. Does anyone know/see a better way?

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  • Memory Leakage using datatables

    - by Vix
    Hi, I have situation in which i'm compelled to retrieve 30,000 records each to 2 datatables.I need to do some manipulations and insert into records into the SQL server in Manipulate(dt1,dt2) function.I have to do this in 15 times as you can see in the for loop.Now I want to know what would be the effective way in terms of memory usage.I've used the first approach.Please suggest me the best approach. (1) for (int i = 0; i < 15; i++) { DataTable dt1 = GetInfo(i); DataTable dt2 = GetData(i); Manipulate(dt1,dt2); } (OR) (2) DataTable dt1 = new DataTable(); DataTable dt2 = new DataTable(); for (int i = 0; i < 15; i++) { dt1=null; dt2=null; dt1 = GetInfo(); dt2 = GetData(); Manipulate(dt1, dt2); } Thanks, Vix.

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  • SQL Server 2008 R2 still requires a trace flag for Lock Pages in Memory

    - by AaronBertrand
    Almost two years ago, I blogged that Lock Pages in Memory was finally available to Standard Edition customers (Enterprise Edition customers had long been deemed smart enough to not abuse this feature). In addition to applying a cumulative update (2005 SP3 CU4 or 2008 SP1 CU2), in order to take advantage of LPIM, you also had to enable trace flag 845. Since the trace flag isn't documented for SQL Server 2008 R2, several of us in the community assumed that it was no longer required (since it was introduced...(read more)

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  • SQL Server 2008 R2 still requires a trace flag for Lock Pages in Memory

    - by AaronBertrand
    Almost two years ago, I blogged that Lock Pages in Memory was finally available to Standard Edition customers (Enterprise Edition customers had long been deemed smart enough to not abuse this feature). In addition to applying a cumulative update (2005 SP3 CU4 or 2008 SP1 CU2), in order to take advantage of LPIM, you also had to enable trace flag 845. Since the trace flag isn't documented for SQL Server 2008 R2, several of us in the community assumed that it was no longer required (since it was introduced...(read more)

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  • SQL SERVER – Weekly Series – Memory Lane – #032

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Complete Series of Database Coding Standards and Guidelines SQL SERVER Database Coding Standards and Guidelines – Introduction SQL SERVER – Database Coding Standards and Guidelines – Part 1 SQL SERVER – Database Coding Standards and Guidelines – Part 2 SQL SERVER Database Coding Standards and Guidelines Complete List Download Explanation and Example – SELF JOIN When all of the data you require is contained within a single table, but data needed to extract is related to each other in the table itself. Examples of this type of data relate to Employee information, where the table may have both an Employee’s ID number for each record and also a field that displays the ID number of an Employee’s supervisor or manager. To retrieve the data tables are required to relate/join to itself. Insert Multiple Records Using One Insert Statement – Use of UNION ALL This is very interesting question I have received from new developer. How can I insert multiple values in table using only one insert? Now this is interesting question. When there are multiple records are to be inserted in the table following is the common way using T-SQL. Function to Display Current Week Date and Day – Weekly Calendar Straight blog post with script to find current week date and day based on the parameters passed in the function.  2008 In my beginning years, I have almost same confusion as many of the developer had in their earlier years. Here are two of the interesting question which I have attempted to answer in my early year. Even if you are experienced developer may be you will still like to read following two questions: Order Of Column In Index Order of Conditions in WHERE Clauses Example of DISTINCT in Aggregate Functions Have you ever used DISTINCT with the Aggregation Function? Here is a simple example about how users can do it. Create a Comma Delimited List Using SELECT Clause From Table Column Straight to script example where I explained how to do something easy and quickly. Compound Assignment Operators SQL SERVER 2008 has introduced new concept of Compound Assignment Operators. Compound Assignment Operators are available in many other programming languages for quite some time. Compound Assignment Operators is operator where variables are operated upon and assigned on the same line. PIVOT and UNPIVOT Table Examples Here is a very interesting question – the answer to the question can be YES or NO both. “If we PIVOT any table and UNPIVOT that table do we get our original table?” Read the blog post to get the explanation of the question above. 2009 What is Interim Table – Simple Definition of Interim Table The interim table is a table that is generated by joining two tables and not the final result table. In other words, when two tables are joined they create an interim table as resultset but the resultset is not final yet. It may be possible that more tables are about to join on the interim table, and more operations are still to be applied on that table (e.g. Order By, Having etc). Besides, it may be possible that there is no interim table; sometimes final table is what is generated when the query is run. 2010 Stored Procedure and Transactions If Stored Procedure is transactional then, it should roll back complete transactions when it encounters any errors. Well, that does not happen in this case, which proves that Stored Procedure does not only provide just the transactional feature to a batch of T-SQL. Generate Database Script for SQL Azure When talking about SQL Azure the most common complaint I hear is that the script generated from stand-along SQL Server database is not compatible with SQL Azure. This was true for some time for sure but not any more. If you have SQL Server 2008 R2 installed you can follow the guideline below to generate a script which is compatible with SQL Azure. Convert IN to EXISTS – Performance Talk It is NOT necessary that every time when IN is replaced by EXISTS it gives better performance. However, in our case listed above it does for sure give better performance. You can read about this subject in the associated blog post. Subquery or Join – Various Options – SQL Server Engine Knows the Best Every single time whenever there is a performance tuning exercise, I hear the conversation from developer where some prefer subquery and some prefer join. In this two part blog post, I explain the same in the detail with examples. Part 1 | Part 2 Merge Operations – Insert, Update, Delete in Single Execution MERGE is a new feature that provides an efficient way to do multiple DML operations. In earlier versions of SQL Server, we had to write separate statements to INSERT, UPDATE, or DELETE data based on certain conditions; however, at present, by using the MERGE statement, we can include the logic of such data changes in one statement that even checks when the data is matched and then just update it, and similarly, when the data is unmatched, it is inserted. 2011 Puzzle – Statistics are not updated but are Created Once Here is the quick scenario about my setup. Create Table Insert 1000 Records Check the Statistics Now insert 10 times more 10,000 indexes Check the Statistics – it will be NOT updated – WHY? Question to You – When to use Function and When to use Stored Procedure Personally, I believe that they are both different things - they cannot be compared. I can say, it will be like comparing apples and oranges. Each has its own unique use. However, they can be used interchangeably at many times and in real life (i.e., production environment). I have personally seen both of these being used interchangeably many times. This is the precise reason for asking this question. 2012 In year 2012 I had two interesting series ran on the blog. If there is no fun in learning, the learning becomes a burden. For the same reason, I had decided to build a three part quiz around SEQUENCE. The quiz was to identify the next value of the sequence. I encourage all of you to take part in this fun quiz. Guess the Next Value – Puzzle 1 Guess the Next Value – Puzzle 2 Guess the Next Value – Puzzle 3 Guess the Next Value – Puzzle 4 Simple Example to Configure Resource Governor – Introduction to Resource Governor Resource Governor is a feature which can manage SQL Server Workload and System Resource Consumption. We can limit the amount of CPU and memory consumption by limiting /governing /throttling on the SQL Server. If there are different workloads running on SQL Server and each of the workload needs different resources or when workloads are competing for resources with each other and affecting the performance of the whole server resource governor is a very important task. Tricks to Replace SELECT * with Column Names – SQL in Sixty Seconds #017 – Video  Retrieves unnecessary columns and increases network traffic When a new columns are added views needs to be refreshed manually Leads to usage of sub-optimal execution plan Uses clustered index in most of the cases instead of using optimal index It is difficult to debug SQL SERVER – Load Generator – Free Tool From CodePlex The best part of this SQL Server Load Generator is that users can run multiple simultaneous queries again SQL Server using different login account and different application name. The interface of the tool is extremely easy to use and very intuitive as well. A Puzzle – Swap Value of Column Without Case Statement Let us assume there is a single column in the table called Gender. The challenge is to write a single update statement which will flip or swap the value in the column. For example if the value in the gender column is ‘male’ swap it with ‘female’ and if the value is ‘female’ swap it with ‘male’. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Random memory corruption going undetected by memtest86

    - by sds
    Thinkpad t520; Ubuntu 12.04.1 LTS; 3.2.0-33-generic 16GB of ram Memtest86+ ran for 26 hours, 9 passes, no errors Booted into "recovery mode"; Ran fsck all filesystems - no errors; "check all packages" - no errors apparent random memory corruption: perl/R/chrome segfault every now and then, seemingly at random; sort(1) produces corrupt unsorted files. What could be possibly wrong and how do I debug it?

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  • MySQL Memory usage

    - by Rob Stevenson-Leggett
    Our MySQL server seems to be using a lot of memory. I've tried looking for slow queries and queries with no index and have halved the peak CPU usage and Apache memory usage but the MySQL memory stays constantly at 2.2GB (~51% of available memory on the server). Here's the graph from Plesk. Running top in the SSH window shows the same figures. Does anyone have any ideas on why the memory usage is constant like this and not peaks and troughs with usage of the app? Here's the output of the MySQL Tuning Primer script: -- MYSQL PERFORMANCE TUNING PRIMER -- - By: Matthew Montgomery - MySQL Version 5.0.77-log x86_64 Uptime = 1 days 14 hrs 4 min 21 sec Avg. qps = 22 Total Questions = 3059456 Threads Connected = 13 Warning: Server has not been running for at least 48hrs. It may not be safe to use these recommendations To find out more information on how each of these runtime variables effects performance visit: http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html Visit http://www.mysql.com/products/enterprise/advisors.html for info about MySQL's Enterprise Monitoring and Advisory Service SLOW QUERIES The slow query log is enabled. Current long_query_time = 1 sec. You have 6 out of 3059477 that take longer than 1 sec. to complete Your long_query_time seems to be fine BINARY UPDATE LOG The binary update log is NOT enabled. You will not be able to do point in time recovery See http://dev.mysql.com/doc/refman/5.0/en/point-in-time-recovery.html WORKER THREADS Current thread_cache_size = 0 Current threads_cached = 0 Current threads_per_sec = 2 Historic threads_per_sec = 0 Threads created per/sec are overrunning threads cached You should raise thread_cache_size MAX CONNECTIONS Current max_connections = 100 Current threads_connected = 14 Historic max_used_connections = 20 The number of used connections is 20% of the configured maximum. Your max_connections variable seems to be fine. INNODB STATUS Current InnoDB index space = 6 M Current InnoDB data space = 18 M Current InnoDB buffer pool free = 0 % Current innodb_buffer_pool_size = 8 M Depending on how much space your innodb indexes take up it may be safe to increase this value to up to 2 / 3 of total system memory MEMORY USAGE Max Memory Ever Allocated : 2.07 G Configured Max Per-thread Buffers : 274 M Configured Max Global Buffers : 2.01 G Configured Max Memory Limit : 2.28 G Physical Memory : 3.84 G Max memory limit seem to be within acceptable norms KEY BUFFER Current MyISAM index space = 4 M Current key_buffer_size = 7 M Key cache miss rate is 1 : 40 Key buffer free ratio = 81 % Your key_buffer_size seems to be fine QUERY CACHE Query cache is supported but not enabled Perhaps you should set the query_cache_size SORT OPERATIONS Current sort_buffer_size = 2 M Current read_rnd_buffer_size = 256 K Sort buffer seems to be fine JOINS Current join_buffer_size = 132.00 K You have had 16 queries where a join could not use an index properly You should enable "log-queries-not-using-indexes" Then look for non indexed joins in the slow query log. If you are unable to optimize your queries you may want to increase your join_buffer_size to accommodate larger joins in one pass. Note! This script will still suggest raising the join_buffer_size when ANY joins not using indexes are found. OPEN FILES LIMIT Current open_files_limit = 1024 files The open_files_limit should typically be set to at least 2x-3x that of table_cache if you have heavy MyISAM usage. Your open_files_limit value seems to be fine TABLE CACHE Current table_cache value = 64 tables You have a total of 426 tables You have 64 open tables. Current table_cache hit rate is 1% , while 100% of your table cache is in use You should probably increase your table_cache TEMP TABLES Current max_heap_table_size = 16 M Current tmp_table_size = 32 M Of 15134 temp tables, 9% were created on disk Effective in-memory tmp_table_size is limited to max_heap_table_size. Created disk tmp tables ratio seems fine TABLE SCANS Current read_buffer_size = 128 K Current table scan ratio = 2915 : 1 read_buffer_size seems to be fine TABLE LOCKING Current Lock Wait ratio = 1 : 142213 Your table locking seems to be fine The app is a facebook game with about 50-100 concurrent users. Thanks, Rob

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  • How In-Memory Database Objects Affect Database Design: The Conceptual Model

    - by drsql
    After a rather long break in the action to get through some heavy tech editing work (paid work before blogging, I always say!) it is time to start working on this presentation about In-Memory Databases. I have been trying to decide on the scope of the demo code in the back of my head, and I have added more and taken away bits and pieces over time trying to find the balance of "enough" complexity to show data integrity issues and joins, but not so much that we get lost in the process of trying to...(read more)

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