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  • Best way to run multiple queries per second on database, performance wise?

    - by Michael Joell
    I am currently using Java to insert and update data multiple times per second. Never having used databases with Java, I am not sure what is required, and how to get the best performance. I currently have a method for each type of query I need to do (for example, update a row in a database). I also have a method to create the database connection. Below is my simplified code. public static void addOneForUserInChannel(String channel, String username) throws SQLException { Connection dbConnection = null; PreparedStatement ps = null; String updateSQL = "UPDATE " + channel + "_count SET messages = messages + 1 WHERE username = ?"; try { dbConnection = getDBConnection(); ps = dbConnection.prepareStatement(updateSQL); ps.setString(1, username); ps.executeUpdate(); } catch(SQLException e) { System.out.println(e.getMessage()); } finally { if(ps != null) { ps.close(); } if(dbConnection != null) { dbConnection.close(); } } } And my DB connection private static Connection getDBConnection() { Connection dbConnection = null; try { Class.forName(DB_DRIVER); } catch (ClassNotFoundException e) { System.out.println(e.getMessage()); } try { dbConnection = DriverManager.getConnection(DB_CONNECTION, DB_USER,DB_PASSWORD); return dbConnection; } catch (SQLException e) { System.out.println(e.getMessage()); } return dbConnection; } This seems to be working fine for now, with about 1-2 queries per second, but I am worried that once I expand and it is running many more, I might have some issues. My questions: Is there a way to have a persistent database connection throughout the entire run time of the process? If so, should I do this? Are there any other optimizations that I should do to help with performance? Thanks

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  • How can manage a FIFO-queue in an database with SQL?

    - by Jonas
    I have two tables in my database, one for In and one for Out. They have two columns, Quantity and Price. How can I write a SQL-query that selects the correct price? In example: If I have 3 items in for 75 and then 3 items in for 80. Then I have two out for 75, and the third out should be for 75 (X) and the fourth out should be for 80 (Y). How can I write the price query for X and Y? They should use the price from the third and forth row. In example, is there any way to SELECT the third row in the In-table? I can not use auto_increment as identifier for i.e. "third" row, because the tables will contain post for other items too. The rows will not be deleted, they will be saved for accountability reasons. SELECT Price FROM In WHERE ...? NEW database design: +----+ | In | +----+------+-------+ | Supply_ID | Price | +-----------+-------+ | 1 | 75 | | 1 | 75 | | 1 | 75 | | 2 | 80 | | 2 | 80 | +-----------+-------+ +-----+ | Out | +-----+-------+-------+ | Delivery_ID | Price | +-------------+-------+ | 1 | 75 | | 1 | 75 | | 2 | X | <- ? | 3 | Y | <- ? +-------------+-------+ OLD database design: +----+ | In | +----+------+----------+-------+ | Supply_ID | Quantity | Price | +-----------+----------+-------+ | 1 | 3 | 75 | | 2 | 3 | 80 | +-----------+----------+-------+ +-----+ | Out | +-----+-------+----------+-------+ | Delivery_ID | Quantity | Price | +-------------+----------+-------+ | 1 | 2 | 75 | | 2 | 1 | X | <- ? | 3 | 1 | Y | <- ? +-------------+----------+-------+

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  • What's the best way to access a MS Access database using PHP?

    - by Jack Roscoe
    Hi, I need to access some data from an MS Access database and retrieve some data from it using PHP. I've looked around the web, and found the following line which seems to correctly connect to the database: $conn->Open("DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=C:\wamp\www\data\MYDB.mdb"); However, I have tried to retrieve some data in the following way: $query = "SELECT pageid FROM pages_table"; $result = mysqli_query($conn, $query); $amount_of_pages = 0; if(mysqli_num_rows($result) <= 0) echo "No results found."; else while($row = mysqli_fetch_array($result, MYSQL_ASSOC)) $amount_of_pages++; And was presented with the following errors: Warning: mysqli_query() expects parameter 1 to be mysqli, object given in C:\wamp\www\data\index.php on line 19 Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, null given in C:\wamp\www\data\index.php on line 23 No results found. I don't really understand the connection to the Access database, is there something I should be doing differently? Thanks in advance for any help.

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  • At what point is it worth using a database?

    - by radix07
    I have a question relating to databases and at what point is worth diving into one. I am primarily an embedded engineer, but I am writing an application using QT to interface with our controller. We are at an odd point where we have enough data that it would be feasible to implement a database (around 700+ items and growing) to manage everything, but I am not sure it is worth the time right now to deal with. I have no problems implementing the GUI with files generated from excel and parsed in, but it gets tedious and hard to track even with VBA scripts. I have been playing around with converting our data into something more manageable for the application side with Microsoft Access and that seems to be working well. If that works out I am only a step (or several) away from using an SQL database and using the QT library to access and modify it. I don't have much experience managing data at this level and am curious what may be the best way to approach this. So what are some of the real benefits of using a database if any in this case? I realize much of this can be very application specific, but some general ideas and suggestions on how to straddle the embedded/application programming line would be helpful. Thanks

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  • In Python, how to make sure database connection will always close before leaving a code block?

    - by Cawas
    I want to prevent database connection being open as much as possible, because this code will run on an intensive used server and people here already told me database connections should always be closed as soon as possible. def do_something_that_needs_database (): dbConnection = MySQLdb.connect(host=args['database_host'], user=args['database_user'], passwd=args['database_pass'], db=args['database_tabl'], cursorclass=MySQLdb.cursors.DictCursor) dbCursor = dbConnection.cursor() dbCursor.execute('SELECT COUNT(*) total FROM table') row = dbCursor.fetchone() if row['total'] == 0: print 'error: table have no records' dbCursor.execute('UPDATE table SET field="%s"', whatever_value) return None print 'table is ok' dbCursor.execute('UPDATE table SET field="%s"', another_value) # a lot more of workflow done here dbConnection.close() # even more stuff would come below I believe that leaves a database connection open when there is no row on the table, tho I'm still really not sure how it works. Anyway, maybe that is bad design in the sense that I could open and close a DB connection after each small block of execute. And sure, I could just add a close right before the return in that case... But how could I always properly close the DB without having to worry if I have that return, or a raise, or continue, or whatever in the middle? I'm thinking in something like a code block, similar to using try, like in the following suggestion, which obviously doesn't work: def do_something_that_needs_database (): dbConnection = MySQLdb.connect(host=args['database_host'], user=args['database_user'], passwd=args['database_pass'], db=args['database_tabl'], cursorclass=MySQLdb.cursors.DictCursor) try: dbCursor = dbConnection.cursor() dbCursor.execute('SELECT COUNT(*) total FROM table') row = dbCursor.fetchone() if row['total'] == 0: print 'error: table have no records' dbCursor.execute('UPDATE table SET field="%s"', whatever_value) return None print 'table is ok' dbCursor.execute('UPDATE table SET field="%s"', another_value) # again, that same lot of line codes done here except ExitingCodeBlock: closeDb(dbConnection) # still, that "even more stuff" from before would come below I don't think there is anything similar to ExitingCodeBlock for an exception, tho I know there is the try else, but I hope Python already have a similar feature... Or maybe someone can suggest me a paradigm move and tell me this is awful and highly advise me to never do that. Maybe this is just something to not worry about and let MySQLdb handle it, or is it?

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  • Web services or shared database for (game) server communication?

    - by jaaronfarr
    We have 2 server clusters: the first is made up of typical web applications backed by SQL databases. The second are highly optimized multiplayer game servers which keep all data in memory. Both clusters communicate with clients via HTTP (Ajax with JSON). There are a few cases in which we need to share data between the two server types, for example, reporting back and storing the results of a game (should ultimately end up in the database). We're considering several approaches for inter-server communication: Just share the MySQL databases between clusters (introduce SQL to the game servers) Sharing data in a distributed key-value store like Memcache, Redis, etc. Use an RPC technology like Google ProtoBufs or Apache Thrift Using RESTful web services (the game server would POST back to the web servers, for example) At the moment, we're leaning towards web services or just sharing the database. Sharing the database seems easy, but we're concerned this adds extra memory and a new dependency into the game servers. Web services provide good separation of concerns and fit with the existing Ajax we use, but add complexity, overhead and many more ways for communication to fail. Are there any other good reasons not to use one or the other approach? Which would be easier to scale?

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  • Informix "Database locale information mismatch"

    - by lmmortal
    I have informix 11.5 running in my Win-2003 box and few databases running in it. System databases have locale en_us.819 My custom databases have locale en_us.57372 (UTF8). There is also application deployed to JBoss 4.0.2 which has few datasources configured for those custom databases. <local-tx-datasource> <jndi-name>InformixDS</jndi-name> <connection-url>jdbc:informix-sqli://@database.server@:@database.port@/tcs_catalog:[email protected]@</connection-url> <driver-class>com.informix.jdbc.IfxDriver</driver-class> <user-name>@database.username@</user-name> <password>@database.password@</password> <new-connection-sql>set lock mode to wait 5</new-connection-sql> <check-valid-connection-sql>select '1' from dual</check-valid-connection-sql> <metadata> <type-mapping>InformixDB</type-mapping> </metadata> I'm logged in as Administrator and when I start JBoss the following error is shown Caused by: java.sql.SQLException: Database locale information mismatch. at com.informix.util.IfxErrMsg.getSQLException(IfxErrMsg.java:373) at com.informix.jdbc.IfxSqli.a(IfxSqli.java:3208) at com.informix.jdbc.IfxSqli.E(IfxSqli.java:3518) at com.informix.jdbc.IfxSqli.dispatchMsg(IfxSqli.java:2353) at com.informix.jdbc.IfxSqli.receiveMessage(IfxSqli.java:2269) at com.informix.jdbc.IfxSqli.executeOpenDatabase(IfxSqli.java:1786) at com.informix.jdbc.IfxSqliConnect.<init>(IfxSqliConnect.java:1327) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:501) at com.informix.jdbc.IfxDriver.connect(IfxDriver.java:254) at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.createManagedConnection(LocalManagedConnectionFactory.java:151) ... 160 more Caused by: java.sql.SQLException at com.informix.util.IfxErrMsg.getSQLException(IfxErrMsg.java:373) at com.informix.jdbc.IfxSqli.E(IfxSqli.java:3523) ... 170 more DB_LOCALE and CLIENT_LOCALE are set to en_us.utf8 for Administrator. When I set in Server Studio DB_LOCALE and CLIENT_LOCALE to en_us.utf8 I can connect my databases. Where should I set DB_LOCALE and CLIENT_LOCALE to avoid this Database locale information mismatch error? Thanks.

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  • MDI WinForm application and duplicate child form memory leak

    - by Steve
    This is a WinForm MDI application problem (.net framework 3.0). It will be described in C#. Sorry it is a bit long because I try to make things as clear as possible. I have a MDI application. At some point I find that one MDI child form is never released. There is a menu that creates the MDI child form and show it. When the MDI child form is closed, it is supposed to be destroyed and the memory taken by it should be given back to .net. But to my surprise, this is not true. All the MDI child form instances are kept in memory. This is obviously a "memory leak". Well, it is not a real leak in .net. It is just that I think the closed form should be dead but somehow there is at least one unknown reference from outside world that still connect with the closed form. I read some articles on the Web. Some says that when the MDI child form is closing, I should unwire all the event handlers, otherwise some event handlers may keep my form alive. Some says that DataBindings should be cleaned before the form is closing otherwise the DataBindings will add references to some global Hashtable and thus keep my form alive. My form contains quite a lot things. Many event handlers and many DataBindings and many BindingSources and few suspected controls containing user control and HelpProvider. I create a big method that unwires all the event handlers from all the relevant controls, clear all the DataBindings and DataSources. The HelpProvider and user controls are disposed carefully. At the end, I find that, I don't have to clear DataBindings and DataSources. Event handlers are definitely causing the problem. And MDI form structure also contributes to something. During my experiments, I find that, if you create a MDI child form, even if you close it, there will still be one instance in the memory. The reference is from PropertyStore of the main form. This means, unless the main form is closed (application ends), there will always be one instance of MDI child form in the memory. The good news is that, no matter how many times you open and close the child form, there will be only one instance, not a big "leak". When it comes to event handlers, things become more tricky. I have to address that, all the event handlers on my form are anonymous event handlers. Here is an example code: //On MDI child form's design code... Button btnSave = new Button(); btnSave.Click += new System.EventHandler(btnSave_Click); Where btnSave_Click is also a method in MDI child form. The above is always the case for various controls and various types of event. To me, this is a bi-directional circular reference. btnSave keeps a reference of MDI child form via the event handler. MDI child form keeps a reference of btnSave instance. To me again, such bi-directional circular reference should not cause any problem for .net's garbage collector. This means that I do not have to explicitly unwire the event when the form is being disposed: btnSave.Click -= btnSave_Click; But the truth is not so. For some event handlers, they are safe. Ignoring them do not cause any duplicate instance. For some other event handlers, they will cause one instance remaining in the memory (similar effect as the MDI form structure, but this time caused by the hanging event handlers). For some other event handlers, they will cause every instance opened in the memory. I am totally confused about the differences between these three types of event handlers. The controls are created in the same way and the event is attached in the same way. What is the difference? (Don't tell me it is the event handle methods that make difference.) Anyone has experience of this wired scenario and has an answer for me? Thanks a lot. So now, for safety issue, I will have to unwire all the event handlers when the form is being disposed. That will be a long list of similar code for each control. Is there a general way of removing events from controls in recursive way using reflection? What about performance issue? That's the end of my story and I am still in the middle of my problem. For any help, I thank you.

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  • What does "single-bit ECC errors were detected on the RAID controller" mean?

    - by jsp
    I have a Dell T7600 with a Perc H710P RAID controller and 4 attached 3TB drives. Over the past few months the RAID controller has been intermittently reporting errors on boot: "no boot device found", "adapter at baseport is not responding", disks frequently reported as missing or failed. I have since replaced the RAID controller, the 4 hard drives, and finally the system's motherboard. After replacing the motherboard and rebooting a few times, I got the error Single bit ECC errors were detected on the RAID controller. Please contact technical support to resolve this issue. After rebooting about 20 more times, I haven't seen the ECC error. The system seems otherwise OK, except for the fact that the disk fans will sometimes start blowing at full blast when the the system is sitting completely idle and not stop until I reboot. Are the ECC errors in memory on the RAID controller? Or, does the RAID controller map in system memory, and the ECC errors are really in system memory? Or, are the ECC errors in the 1GB cache that resides in the RAID controller?

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  • High load average, low CPU and IO (Centos 5.7)

    - by Ben
    A Drupal 7 site with CiviCRM, after running smoothly for a year on a 1&1 VPS suddenly became unresponsive. Now pages eventually load, but can take more than a minute. Looking at resource use in Virtuozzo, the load average carries a warning, and has remained above 1. While I understand this isn't particularly high, this is a change from when the site was working. Here is a typical snapshot of top: top - 03:10:32 up 3:21, 1 user, load average: 1.16, 1.22, 1.30 Tasks: 43 total, 1 running, 42 sleeping, 0 stopped, 0 zombie Cpu(s): 0.1%us, 0.1%sy, 0.1%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 2097152k total, 1015112k used, 1082040k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached CPU idle level never seems to go much below 70%. wa is virtually always at 0. There appears to be lots of free memory. And here is some vmstat output, again showign wa at 0, plenty of free memory, and an idle CPU: procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------ r b swpd free buff cache si so bi bo in cs us sy id wa st 2 0 0 1100872 0 0 0 0 2783 23672 0 538 1 0 99 0 0 1 0 0 1100872 0 0 0 0 0 16 0 101754 0 0 100 0 0 0 0 0 1100872 0 0 0 0 0 17 0 103133 0 0 100 0 0 0 0 0 1100872 0 0 0 0 0 1 0 102080 0 0 100 0 0 1 0 0 1100872 0 0 0 0 0 6 0 99881 0 0 100 0 0 0 0 0 1100872 0 0 0 0 0 1 0 105187 0 0 100 0 0 I've spoken to 1&1 but they don't have any ideas as to what could be causing the high load average. Instead they suggested an upgrade :) I've looked for processes that might be causing this, examined MySQL showprocesslist, and restarted the container with no result. Does anyone have more troubleshooting suggestions or insights?

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  • Throughput; capacity planning help for C10K like design

    - by z8000
    I am designing a network service in which clients connect and stay connected -- the model is not far off from IRC less the s2s connections. I could use some help understanding how to do capacity planning, in particular with the system resource costs associated with handling messages from/to clients. There's an article that tried to get 1 million clients connected to the same server [1]. Of course, most of these clients were completely idle in the test. If the clients sent a message every 5 seconds or so the system would surely be brought to its knees. But... How do you do less hand-waving and you know, measure such a breaking point? We're talking about messages being sent by a client over a TCP socket, into the kernel, and read by an application. The data is shuffled around in memory from one buffer to another. Do I need to consider memory throughput ("5 GT/s" [2], etc.)? I'm pretty sure I have the ability to measure the basic memory requirements due to TCP/IP buffers, expected bandwidth, and CPU resources required to process messages. I'm a little dim on what I'm calling "thoughput". Help! Also, does anyone really do this? Or, do most people sort of hand-wave and see what the real world offers, and then react appropriately? [1] http://www.metabrew.com/article/a-million-user-comet-application-with-mochiweb-part-3/ [2] http://en.wikipedia.org/wiki/GT/s

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  • RAM being displayed is lesser than the actual in my Windows 7

    - by Prateek Somani
    I am using Windows 7 and Ubuntu on the same machine. Earlier I had 3 GB of RAM,but now the Windows is displaying just 1 GB of RAM. Please also find the output of the free command in my Ubuntu : total used free shared buffers cached Mem: 1008208 904808 103400 5736 13516 239596 -/+ buffers/cache: 651696 356512 Swap: 3127292 10252 3117040 Has the swap memory consumed my 2 GB of RAM? Will I be able to use the whole of 3GB of the RAM in my Windows? Regards, Prateek Update : I tried to run the lshw command and I got the following output : *-memory description: System Memory physical id: 1b slot: System board or motherboard size: 1GiB *-bank:0 description: SODIMM DDR3 Synchronous 1067 MHz (0.9 ns) product: HMT112S6BFR6C-H9 vendor: Hynix physical id: 0 serial: 2C71D069 slot: Bottom - Slot 1 size: 1GiB width: 64 bits clock: 1067MHz (0.9ns) *-bank:1 description: SODIMM DDR3 Synchronous 1067 MHz (0.9 ns) [empty] product: 16JSF25664HZ-1G4F1 vendor: Micron physical id: 1 serial: FD421821 slot: Bottom - Slot 2 width: 64 bits clock: 1067MHz (0.9ns) Why it is able to detect the vendor/product name of the bank-1 RAM, why can't it detect the RAM size and other details ? Has my RAM got faulty?

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  • RAM ok in memtest86+ == RAM ok after wake from sleep?

    - by twon33
    I have a Windows XP (32-bit) system that appears stable in normal operation, but was repeatably freezing (hard lock, no BSOD) a minute or so after waking from S3 sleep. Some Googling against the motherboard model and memory manufacturer suggested that I might need to bump up the memory voltage, so I tried it and it now seems to resume without freezing. However, I don't really trust it and I'd like to validate that it's actually stable, especially after resuming from sleep. I've run Prime95 for a few hours with no issues, and am planning an overnight run of Memtest86+, which I expect to pass because the system has been solid whenever I've run it without putting it to sleep. Does something like Memtest86+ exist that actually invokes S3 sleep during operation? Clearly it would need an operator to wake the computer to resume testing, but I don't think I've ever heard of a memory test tool that can do this. Alternately, am I wasting my time? Should a clean bill of health from Memtest86+ indicate stability regardless of whether sleep is involved, or, conversely, does my original problem indicate that Memtest86+ would have failed eventually with the stock voltage if I'd run it, sleep or not?

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  • What can cause kernel out_of_memory error?

    - by nbolton
    I'm running Debian GNU/Linux 5.0 and I'm experiencing intermittent out_of_memory errors coming from the kernel. The server stops responding to all but pings, and I have to reboot the server. # uname -a Linux xxx 2.6.18-164.9.1.el5xen #1 SMP Tue Dec 15 21:31:37 EST 2009 x86_64 GNU/Linux This seems to be the important bit from /var/log/messages Dec 28 20:16:25 slarti kernel: Call Trace: Dec 28 20:16:25 slarti kernel: [<ffffffff802bedff>] out_of_memory+0x8b/0x203 Dec 28 20:16:25 slarti kernel: [<ffffffff8020f825>] __alloc_pages+0x245/0x2ce Dec 28 20:16:25 slarti kernel: [<ffffffff8021377f>] __do_page_cache_readahead+0xc6/0x1ab Dec 28 20:16:25 slarti kernel: [<ffffffff80214015>] filemap_nopage+0x14c/0x360 Dec 28 20:16:25 slarti kernel: [<ffffffff80208ebc>] __handle_mm_fault+0x443/0x1337 Dec 28 20:16:25 slarti kernel: [<ffffffff8026766a>] do_page_fault+0xf7b/0x12e0 Dec 28 20:16:25 slarti kernel: [<ffffffff8026ef17>] monotonic_clock+0x35/0x7b Dec 28 20:16:25 slarti kernel: [<ffffffff80262da3>] thread_return+0x6c/0x113 Dec 28 20:16:25 slarti kernel: [<ffffffff8021afef>] remove_vma+0x4c/0x53 Dec 28 20:16:25 slarti kernel: [<ffffffff80264901>] _spin_lock_irqsave+0x9/0x14 Dec 28 20:16:25 slarti kernel: [<ffffffff8026082b>] error_exit+0x0/0x6e Full snippet here: http://pastebin.com/a7eWf7VZ I thought that perhaps the server was actually running out of memory (it has 1GB physical memory), but my Cacti memory graph looks OK to me... But strangely the load graph goes through the roof shortly before the kernel crashes: What logs can I look at for more info? Update: Maybe noteworthy - the CPU percentage and network traffic graphs were both normal at the time of the crash. The only abnormality was the average load graph.

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  • After upgrading to 2008 R2 Enterprise and installing more RAM, Windows can only see 4.00 GB

    - by Tom Crane
    (I have also posted this on technet but I'm running out of ideas) I've upgraded from Windows Server 2008 R2 Standard to Enterprise in order to make use of more RAM. The server previously had 32GB of RAM. The upgrade from Standard to Enterprise, using DISM, seemed to go OK, so I powered down and installed the RAM. This a Dell Poweredge T710, I was taking it from 32GB to 72GB. The BIOS recognised the RAM, although I needed to change from "Advanced ECC" to "Optimizer" mode for it to use all of it. After rebooting, windows can see the RAM but in the system panel will display: Installed memory (RAM): 72.0 GB (4.00 GB usable) In the resource monitor, the remainder of the RAM is showing as reserved for hardware. I've tried various RAM configurations, including reverting it to the same chips and same configuration as before the upgrade, but always just 4.00 GB is showing up as usable. Following some threads on these forums I've gone into msconfig and set the maximum memory "by hand" but that doesn't fix the problem. BIOS doesn't seem to have anything that looks like memory remapping which is another suggestion that has come up. How do I make this RAM available to Windows? It was available before the upgrade, because I could use the full 32GB RAM the server had to start with. A screenshot (this is after reverting to the original RAM configuration) http://screencast.com/t/5FuzevdNb I don't know if it's related, but my remote desktop configuration has also disappeared: screencast.com/t/mYedomeQWS (the bottom half of this dialog should allow me to configure Remote Desktop, it was working before the upgrade but now it isn't).

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  • less maximum buffer size?

    - by Tyzoid
    I was messing around with my system and found a novel way to use up memory, but it seems that the less command only holds a limited amount of data before stopping/killing the command. To test, run (careful! uses lots of system memory very fast!) $ cat /dev/zero | less From my testing, it looks like the command is killed after less reaches 2.5 gigabytes of memory, but I can't find anything in the man page that suggests that it would limit it in such a way. In addition, I couldn't find any documentation via the google on the subject. Any light to this quite surprising discovery would be great! System Information: Quad core intel i7, 8gb ram. $ uname -a Linux Tyler-Work 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux $ less --version less 458 (GNU regular expressions) Copyright (C) 1984-2012 Mark Nudelman less comes with NO WARRANTY, to the extent permitted by law. For information about the terms of redistribution, see the file named README in the less distribution. Homepage: http://www.greenwoodsoftware.com/less $ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 14.04 LTS Release: 14.04 Codename: trusty

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  • Are these three brand new sticks of RAM really dead?

    - by David Brown
    I'm working on a Dell Dimension 4700 desktop for a friend. It came with 512MB of DDR2 RAM (two sticks of 256MB). One morning, it started blue screening on startup with no helpful error messages. It refused to boot into any form of Windows installation, including Safe Mode, original recovery disk, and my custom Windows PE disk. It did boot into the Ultimate Boot CD, so I ran memtest86, which reported errors everywhere. I removed one stick of RAM and the system booted up just fine. I moved the remaining stick into each slot and the system continued to operate normally, so I came to the conclusion that the stick that I removed was dead. I ordered an exact replacement, along with 2 more sticks of 256MB DDR2 (again, exactly the same as the original), bringing the total system memory to 1GB. Upon installing the three brand new sticks, the system blue screened again, this time stating that win32k.sys attempted to write to read-only memory. I inserted my custom Windows PE disk in order to get a better look at the memory dump with BlueScreenView, but it refused to boot and produced another blue screen, but without an error message. I removed each new stick one-by-one, restarting each time. It continued to blue screen until I was left with only the original stick. I then tried inserting the new sticks in various different orders, but this only produced more blue screens. I reinserted all three sticks (along with the original) and ran memtest86 again, which reported errors all over the place. So, now I'm right back where I started. I don't think it could be the slots themselves, because I can plug the original stick into any slot and it works just fine. System setup reports each stick correctly and shows the total as 1GB, however. It just seems strange to me that all three brand new sticks of RAM could be dead on arrival. Is there something I missed? Or should I just go ahead and RMA them?

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  • Problem loading Oracle client libraries when running in a NAnt build

    - by Chris Farmer
    I am trying to use dbdeploy to manage Oracle schema changes. I can run it successfully from the command line to get it to generate my change scripts, but when I try to execute it via the dbdeploy NAnt task running through TeamCity, I get an error: System.Data.OracleClient requires Oracle client software version 8.1.7 or greater. I do have the Oracle 10.2.0.2 client software installed. It's the first entry in the system path, and the dbdeploy.exe app is able to successfully negotiate an Oracle connection. The dbdeploy code dynamically loads the System.Data.OracleClient assembly, which in-turn tries to use the Oracle client bits to talk to the database. This is what is failing in my NAnt environment. I have verified the following points: The same user identity is running the process in both cases The same working directory is used in both cases The same dbdeploy code is running in both cases and with the same supplied parameters The same database connection string is being used in both cases The same ADO.NET assembly is being dynamically loaded in both cases (System.Data.OracleClient, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089) Here's the top of the stack trace during the error: at System.Data.OracleClient.OCI.DetermineClientVersion() at System.Data.OracleClient.OracleInternalConnection.OpenOnLocalTransaction (String userName, String password, String serverName, Boolean integratedSecurity, Boolean unicode, Boolean omitOracleConnectionName) at System.Data.OracleClient.OracleInternalConnection..ctor( OracleConnectionString connectionOptions) at System.Data.OracleClient.OracleConnectionFactory.CreateConnection( DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningObject) at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection( DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) at System.Data.ProviderBase.DbConnectionPool.CreateObject( DbConnection owningObject) at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest( DbConnection owningObject) at System.Data.ProviderBase.DbConnectionPool.GetConnection( DbConnection owningObject) at System.Data.ProviderBase.DbConnectionFactory.GetConnection( DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionClosed.OpenConnection( DbConnection outerConnection, DbConnectionFactory connectionFactory) at System.Data.OracleClient.OracleConnection.Open() at Net.Sf.Dbdeploy.Database.DatabaseSchemaVersionManager. GetCurrentVersionFromDb() My main question is this: how can I discover what's different about these running environments to see why my Oracle client software can't be loaded?

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  • EF4 Generate Database

    - by shaneseaton
    Hi, I am trying my hardest to find the simplest way to create a basic "model first" entity framework example. However I am struggling with the actually generation of the database, particularly the running of the SQL against the database. Tools Visual Studio 2010 SQL Server 2008 Express Process Create a new class project Add a new Server-Database item (mdf) named "Database1.mdf" to the project Add an empty ADO.net Entity Model Create a simple entity (Person: Id, Name) Generate the Script selecting the Database1 connection created for me by visual studio Right click the script editor and select the "Execute SQL..." option Log in to SQLEXPRESS This is where is falls over saying it cant find a database name "Database1". The "problem" is that the SQL server has not had Database1 attached to it. I am 100% positive that Visual Studio use to attach a database to SQLExpress when it created a new database (Step 2). This appears to not be the case any more (even the beta of VS2010 did it). Can someone confirm this? or tell me how to get this to happen? Is there a way that I can modify the TSQL script to use an un-attached database. ie a file. I know I can use SQL Management Studio or sqlcmd to attach the database, but I would ideally like to avoid the solutions as I would like to see the cleanest method of just using visual studio. Ideal Solutions (in order of most prefered) Get visual studio to attach the newly created database Modify the generated SQL to point to file Thanks in advance.

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  • Database structure for ecommerce site

    - by imanc
    Hey Guys, I have been tasked with designing an ecommerce solution. The aspect that is causing me the most problems is the database. Currently the site consists of 10+ country based shops each with their own database (all residing on the same mysql instance). For the new site I'd rather all these shop databases be merged into one database so that all tables (products, orders, customers etc.) have a shop_id field. From a programming perspective this seems to make the most sense as we won't have to manage data across multiple databases. Currently the entire site generates about 120k orders a year, but is experiencing fairly heavy growth and we need to design a solution that will scale. In 5 years there may be more than a million orders per year and a database that contains 5 years order history (archiving maybe a solution here). The question is - do we use a single database, or do we keep the database-per-shop structure? I am currently trying to find supporting evidence for either avenue. The company I am designing the solution for prefer the per-shop database structure because they believe it will allow the sites to scale. But my argument is that the shop's database probably won't get that busy over the next few years that they exceed the capacity of a mysql database and a "no expenses spared" hardware set-up. I am wondering if anyone has any advice either way? Does anyone have experience with websites / ecommerce sites that have tables containing millions of records? I know there is probably not a clear answer here, but at what stage do we have too many records or too large table files to have a fast loading site? Also, if anyone has any advice on sources of information - books, websites, etc. where I can do further research, it would be highly appreciated! Cheers, imanc

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  • Configuring Multiple Instances of MySQL in Solaris 11

    - by rajeshr
    Recently someone asked me for steps to configure multiple instances of MySQL database in an Operating Platform. Coz of my familiarity with Solaris OE, I prepared some notes on configuring multiple instances of MySQL database on Solaris 11. Maybe it's useful for some: If you want to run Solaris Operating System (or any other OS of your choice) as a virtualized instance in desktop, consider using Virtual Box. To download Solaris Operating System, click here. Once you have your Solaris Operating System (Version 11) up and running and have Internet connectivity to gain access to the Image Packaging System (IPS), please follow the steps as mentioned below to install MySQL and configure multiple instances: 1. Install MySQL Database in Solaris 11 $ sudo pkg install mysql-51 2. Verify if the mysql is installed: $ svcs -a | grep mysql Note: Service FMRI will look similar to the one here: svc:/application/database/mysql:version_51 3. Prepare data file system for MySQL Instance 1 zfs create rpool/mysql zfs create rpool/mysql/data zfs set mountpoint=/mysql/data rpool/mysql/data 4. Prepare data file system for MySQL Instance 2 zfs create rpool/mysql/data2 zfs set mountpoint=/mysql/data rpool/mysql/data2 5. Change the mysql/datadir of the MySQL Service (SMF) to point to /mysql/data $ svcprop mysql:version_51 | grep mysql/data $ svccfg -s mysql:version_51 setprop mysql/data=/mysql/data 6. Create a new instance of MySQL 5.1 (a) Copy the manifest of the default instance to temporary directory: $ sudo cp /lib/svc/manifest/application/database/mysql_51.xml /var/tmp/mysql_51_2.xml (b) Make appropriate modifications on the XML file $ sudo vi /var/tmp/mysql_51_2.xml - Change the "instance name" section to a new value "version_51_2" - Change the value of property name "data" to point to the ZFS file system "/mysql/data2" 7. Import the manifest to the SMF repository: $ sudo svccfg import /var/tmp/mysql_51_2.xml 8. Before starting the service, copy the file /etc/mysql/my.cnf to the data directories /mysql/data & /mysql/data2. $ sudo cp /etc/mysql/my.cnf /mysql/data/ $ sudo cp /etc/mysql/my.cnf /mysql/data2/ 9. Make modifications to the my.cnf in each of the data directories as required: $ sudo vi /mysql/data/my.cnf Under the [client] section port=3306 socket=/tmp/mysql.sock ---- ---- Under the [mysqld] section port=3306 socket=/tmp/mysql.sock datadir=/mysql/data ----- ----- server-id=1 $ sudo vi /mysql/data2/my.cnf Under the [client] section port=3307 socket=/tmp/mysql2.sock ----- ----- Under the [mysqld] section port=3307 socket=/tmp/mysql2.sock datadir=/mysql/data2 ----- ----- server-id=2 10. Make appropriate modification to the startup script of MySQL (managed by SMF) to point to the appropriate my.cnf for each instance: $ sudo vi /lib/svc/method/mysql_51 Note: Search for all occurences of mysqld_safe command and modify it to include the --defaults-file option. An example entry would look as follows: ${MySQLBIN}/mysqld_safe --defaults-file=${MYSQLDATA}/my.cnf --user=mysql --datadir=${MYSQLDATA} --pid=file=${PIDFILE} 11. Start the service: $ sudo svcadm enable mysql:version_51_2 $ sudo svcadm enable mysql:version_51 12. Verify that the two services are running by using: $ svcs mysql 13. Verify the processes: $ ps -ef | grep mysqld 14. Connect to each mysqld instance and verify: $ mysql --defaults-file=/mysql/data/my.cnf -u root -p $ mysql --defaults-file=/mysql/data2/my.cnf -u root -p Some references for Solaris 11 newbies Taking your first steps with Solaris 11 Introducing the basics of Image Packaging System Service Management Facility How To Guide For a detailed list of official educational modules available on Solaris 11, please visit here For MySQL courses from Oracle University access this page.

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  • [EF + Oracle] Entities

    - by JTorrecilla
    Prologue Following with the Serie I started yesterday about Entity Framework with Oracle, Today I am going to start talking about Entities. What is an Entity? A Entity is an object of the EF model corresponding to a record in a DB table. For example, let’s see, in Image 1 we can see one Entity from our model, and in the second one we can see the mapping done with the DB. (Image 1) (Image 2) More in depth a Entity is a Class inherited from the abstract class “EntityObject”, contained by the “System.Data.Objects.DataClasses” namespace. At the same time, this class inherits from the following Class and interfaces: StructuralObject: It is an Abstract class that inherits from INotifyPropertyChanging and INotifyPropertyChanged interfaces, and it exposes the events that manage the Changes of the class, and the functions related to check the data types of the Properties from our Entity.  IEntityWithKey: Interface which exposes the Key of the entity. IEntityWithChangeTracker: Interface which lets indicate the state of the entity (Detached, Modified, Added…) IEntityWithRelationships: Interface which indicates the relations about the entity. Which is the Content of a Entity? A Entity is composed by: Properties, Navigation Properties and Methods. What is a Property? A Entity Property is an object that represents a column from the mapped table from DB. It has a data type equivalent in .Net Framework to the DB Type. When we create the EF model, VS, internally, create the code for each Entity selected in the Tables step, such all methods that we will see in next steps. For each property, VS creates a structure similar to: · Private variable with the mapped Data type. · Function with a name like On{Property_Name}Changing({dataType} value): It manages the event which happens when we try to change the value. · Function with a name like On{Property_Name}Change: It manages the event raised when the property has changed successfully. · Property with Get and Set methods: The Set Method manages the private variable and do the following steps: Raise Changing event. Report the Entity is Changing. Set the prívate variable. For it, Use the SetValidValue function of the StructuralObject. There is a function for each datatype, and the functions takes 2 params: the value, and if the prop allow nulls. Invoke that the entity has been successfully changed. Invoke the Changed event of the Prop. ReportPropertyChanging and ReportPropertyChanged events, let, respectively, indicate that there is pending changes in the Entity, and the changes have success correctly. While the ReportPropertyChanged is raised, the Track State of the Entity will be changed. What is a Navigation Property? Navigation Properties are a kind of property of the type: EntityCollection<TEntity>, where TEntity is an Entity type from the model related with the current one, it is said, is a set of record from a related table in the DB. The EntityCollection class inherits from: · RelatedEnd: There is an abstract class that give the functions needed to obtein the related objects. · ICollection<TEntity> · IEnumerable<TEntity> · IEnumerable · IListSource For the previous interfaces, I wish recommend the following post from Jose Miguel Torres. Navigation properties allow us, to get and query easily objects related with the Entity. Methods? There is only one method in the Entity object. “Create{Entity}”, that allow us to create an object of the Entity by sending the parameters needed to create it. Finally After this chapter, we know what is an Entity, how is related to the DB and the relation to other Entities. In following chapters, we will se CRUD operations(Create, Read, Update, Delete).

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  • Ulimit settings in Oracle 11g on Linux 5

    - by Stuart
    Is there an issue with "Ulimit -Hn" being set too low (at 1024) when (Oracle recommend 65536)? This is for Oracle 64-bit 11g on Linux 5. It is one of the settings that appears to be woefully short of its recommendation. But I am also aware that the database server in question is an Oracle Data Guard Local Standby and should only really have a connection or two from its Primary database server (to ship the redo logs across). The Local Standby database server has 'hung' about 3 times in as many months and then requires a reboot. I do not have access to this server, so rely on others to look at logs etc. The sanity check on kernel params uncovered the low value for "ulimit -Hn". Has anyone ever seen that 'low' value cause a hang or crash?

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  • How do I use C# and ADO.NET to query an Oracle table with a spatial column of type SDO_GEOMETRY?

    - by John Donahue
    My development machine is running Windows 7 Enterprise, 64-bit version. I am using Visual Studio 2010 Release Candidate. I am connecting to an Oracle 11g Enterprise server version 11.1.0.7.0. I had a difficult time locating Oracle client software that is made for 64-bit Windows systems and eventually landed here to download what I assume is the proper client connectivity software. I added a reference to "Oracle.DataAccess" which is version 2.111.6.0 (Runtime Version is v2.0.50727). I am targeting .NET CLR version 4.0 since all properties of my VS Solution are defaults and this is 2010 RC. I was then able to write a console application in C# that established connectivity, executed a SELECT statement, and properly returned data when the table in question does NOT contain a spatial column. My problem is that this no longer works when the table I query has a column of type SDO_GEOMETRY in it. Below is the simple console application I am trying to run that reproduces the problem. When the code gets to the line with the "ExecuteReader" command, an exception is raised and the message is "Unsupported column datatype". using System; using System.Data; using Oracle.DataAccess.Client; namespace ConsoleTestOracle { class Program { static void Main(string[] args) { string oradb = string.Format("Data Source={0};User Id={1};Password={2};", "hostname/servicename", "login", "password"); try { using (OracleConnection conn = new OracleConnection(oradb)) { conn.Open(); OracleCommand cmd = new OracleCommand(); cmd.Connection = conn; cmd.CommandText = "select * from SDO_8307_2D_POINTS"; cmd.CommandType = CommandType.Text; OracleDataReader dr = cmd.ExecuteReader(); } } catch (Exception e) { string error = e.Message; } } } } The fact that this code works when used against a table that does not contain a spatial column of type SDO_GEOMETRY makes me think I have my windows 7 machine properly configured so I am surprised that I get this exception when the table contains different kinds of columns. I don't know if there is some configuration on my machine or the Oracle machine that needs to be done, or if the Oracle client software I have installed is wrong, or old and needs to be updated. Here is the SQL I used to create the table, populate it with some rows containing points in the spatial column, etc. if you want to try to reproduce this exactly. SQL Create Commands: create table SDO_8307_2D_Points (ObjectID number(38) not null unique, TestID number, shape SDO_GEOMETRY); Insert into SDO_8307_2D_Points values (1, 1, SDO_GEOMETRY(2001, 8307, null, SDO_ELEM_INFO_ARRAY(1, 1, 1), SDO_ORDINATE_ARRAY(10.0, 10.0))); Insert into SDO_8307_2D_Points values (2, 2, SDO_GEOMETRY(2001, 8307, null, SDO_ELEM_INFO_ARRAY(1, 1, 1), SDO_ORDINATE_ARRAY(10.0, 20.0))); insert into user_sdo_geom_metadata values ('SDO_8307_2D_Points', 'SHAPE', SDO_DIM_ARRAY(SDO_DIM_ELEMENT('Lat', -180, 180, 0.05), SDO_DIM_ELEMENT('Long', -90, 90, 0.05)), 8307); create index SDO_8307_2D_Point_indx on SDO_8307_2D_Points(shape) indextype is mdsys.spatial_index PARAMETERS ('sdo_indx_dims=2' ); Any advice or insights would be greatly appreciated. Thank you.

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