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• Disaster Recovery Example

  Previously, I use to work for a small internet company that sells dental plans online. Our primary focus concerning disaster prevention and recovery is on our corporate website and private intranet site. We had a multiphase disaster recovery plan that includes data redundancy, load balancing, and off-site monitoring. Data redundancy is a key aspect of our disaster recovery plan. The first phase of this is to replicate our data to multiple database servers and schedule daily backups of the databases that are stored off site. The next phase is the file replication of data amongst our web servers that are also backed up daily by our collocation. In addition to the files located on the server, files are also stored locally on development machines, and again backed up using version control software. Load balancing is another key aspect of our disaster recovery plan. Load balancing offers many benefits for our system, better performance, load distribution and increased availability. With our servers behind a load balancer our system has the ability to accept multiple requests simultaneously because the load is split between multiple servers. Plus if one server is slow or experiencing a failure the traffic is diverted amongst the other servers connected to the load balancer allowing the server to get back online. The final key to our disaster recovery plan is off-site monitoring that notifies all IT staff of any outages or errors on the main website encountered by the monitor. Messages are sent by email, voicemail, and SMS. According to Disasterrecovery.org, disaster recovery planning is the way companies successfully manage crises with minimal cost and effort and maximum speed compared to others that are forced to make decision out of desperation when disasters occur. In addition Sun Guard stated in 2009 that the first step in disaster recovery planning is to analyze company risks and factor in fixed costs for things like hardware, software, staffing and utilities, as well as indirect costs, such as floor space, power protection, physical and information security, and management. Also availability requirements need to be determined per application and system as well as the strategies for recovery.

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• Oracle OpenWorld Highlights

  - by Doug Reid

  We are in the final days of Oracle OpenWorld 2012 and the data integration team have been hard at work giving sessions, meeting customers, demonstrating product and conducting hands-on labs.    It has been a great conference, but the best part is meeting our customers and learning about all the great implementations of our products.  Wednesday was the last day that the exhibition hall was open and attendees were getting in their final opportunities to see our products and meet with the product management team.   Two hours before the close of the hall, people lined up to learn about GoldenGate 11gR2, Monitor, Adapters, Veridata, and all the different use cases.    Here's a picture of Sjaak Vossepoel, who is our DIS Sales Consulting Manager for EMEA speaking to a potential customer on the options of using Oracle GoldenGate for heterogenous data replication.  Over the last two days, the GoldenGate team ran two labs; Introduction to Oracle GoldenGate Veridata and Deep Dive into Oracle GoldenGate.   Both of the labs were completely booked out and unfortunately we had to turn away people.   BUT,  all of our labs were recorded recently so if you were not able to get into the lab or did not have enough time to complete your labs, visit youtube.com/oraclegoldengate to see a  complete recording of the labs we used at OpenWorld plus more.  Here are a couple pictures from the Deep Dive into Oracle GoldenGate lead by Chis Lawless from the Product Management team.   Thanks to the GoldenGate Hands-on Lab team for putting on a great session!!! We will post more information about where you can find additional details on OpenWorld as they become public.   

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• Ref to map vs. map to refs vs. multiple refs

  - by mikera

  I'm working on a GUI application in Swing+Clojure that requires various mutable pieces of data (e.g. scroll position, user data, filename, selected tool options etc.). I can see at least three different ways of handling this set of data: Create a ref to a map of all the data: (def data (ref { :filename "filename.xml" :scroll [0 0] })) Create a map of refs to the individual data elements: (def datamap { :filename (ref "filename.xml") :scroll (ref [0 0]) })) Create a separate ref for each in the namespace: (def scroll (ref [0 0])) (def filename (ref "filename.xml")) Note: This data will be accessed concurrently, e.g. by background processing threads or the Swing event handling thread. However there probably isn't a need for consistent transactional updates of multiple elements. What would be your recommended approach and why?

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• Is it a good idea to use a computed column as part of a primary key ?

  - by Brann

  I've got a table defined as : OrderID bigint NOT NULL, IDA varchar(50) NULL, IDB bigint NULL, [ ... 50 other non relevant columns ...] The natural primary key for this table would be (OrderID,IDA,IDB), but this it not possible because IDA and IDB can be null (they can both be null, but they are never both defined at the same time). Right now I've got a unique constraint on those 3 columns. Now, the thing is I need a primary key to enable transactional replication, and I'm faced with two choices : Create an identity column and use it as a primary key Create a non-null computed column C containing either IDA or IDB or '' if both columns were null, and use (OrderID,C) as my primary key. The second alternative seams cleaner as my PK would be meaningful, and is feasible (see msdn link), but since I've never seen this done anywhere, I was wondering if they were some cons to this approach.

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• Temporary intermediate table

  - by user289429

  In our project to generate massive reports in oracle we use some permanent table to hold intermediate results. For example to generate one report we run few queries and populate the table, at the final step we join the intermediate table with huge application tables. These intermediate tables are cleared for next report run. We have few concerns in performance areas. These intermediate tables are transactional and don't have statistics. Is it good idea to join these with application tables which are partitioned and have up to date statistics. We need these results stored in the intermediate tables to be available across requests from UI hence we are not in a position to use oracle provided temporary tables. Any thoughts on what could be done would be appreciated.

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• Late feedback

  - by Sveta Smirnova

  MySQL Community team asked me to write about Devconf 2013 few months ago. Conference was in June, 2013, but I remembered about this my promise only now: month later after my participating in MySQL Connect and Expert Troubleshooting seminar (change country to United Kingdom if you see blank page). I think it is too late for the feedback, but I still have few thoughts which I want to record.DevConf (former PHPConf) always was a place where I tried new topics. At first, because I know audience there very well and they will be bored if I repeat a story which I was telling last year, but also because it is much easier to get feedback in your own native language. But last years my habit seems started to change and I presented improved version of my 2012 MySQL Connect talk about MySQL backups. Of course, I also had a seminar with unique topic, made for this conference first time: Troubleshooting MySQL Performance with EXPLAIN and Using Performance Schema to Troubleshoot MySQL. And these topics, improved, were presented at the expert seminar. It is interesting how my habit changes and one public speaking activity interferes next one.What is good about DevConf is it forces you to create new ideas and do it really well, because audience is not forgiving at all, so they catch everything you miss or prepared not good enough. This can be bad if you want to make a marketing-style topic for free, but allows to present technical features in really good details: all these sudden discussions really help.In year 2013 Oracle had a booth at the conference and was presented by a bunch of people. Dmitry Lenev presented topic "New features of replication in MySQL 5.6" and Victoria Reznichenko worked on the booth. What was new at the conference this year is greater interest in NoSQL, scale and fast development solutions. This, unfortunately, means not so huge interest in MySQL as it was earlier. However, at the same time, "Common" track was really MySQL track: not only Oracle, but people from other companies presented about it.

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• Microsoft Lowers Cloud Barrier To Entry

  - by Herve Roggero

  Once in a while, the technology stack changes enough to create a disturbance in the IT industry. Microsoft did just that today and has officially closed the gap with its #1 competitor: Amazon. What is remarkable is that Microsoft is no longer an alternative to Amazon, it is becoming a clear leader in that space. Some of the new features include official support for durable Virtual Machines with high availability (cross-geographic replication), free WebSites to try Azure, MySQL database at no charge, a new distributed low-latency cache feature, Linux support, support with existing VPN hardware for seamless on-premise integration, a new partner ecosystem and much, much more. Amazon had an edge against Windows Azure in the IaaS (Infrastructure as a Service) space, until now. With the latest release from Microsoft Azure, the gap has been filled. In fact, it seems Amazon may now have a gap to fill… This is great news to everyone; it seems that cloud offerings are becoming more standardized with the more mature cloud providers, and the management stack and quality of service of each cloud provider is increasingly becoming the differentiator. With today’s announcements, it is becoming clear that cloud providers are pushing hard to increase their service footprint and lowering typical barriers to entry such as support for open-source operating systems, free trial offers, higher availability, faster deployment times and simpler enterprise integration.

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• Does it make sense to use BOTH mongodb and mysql in the same rails application?

  - by Brian Armstrong

  I have a good reason to use mongodb for part of my app. But people generally describe it as not a good fit for "transactional" applications like a bank where transactions have to be exact/consistent, etc. Does it make sense to split the models up in Rails and have some of them use MySql and others mongo? Or will this generally cause more problems than it's worth? I'm not building a banking app or anything, but was thinking it might make sense for my users table or or transactions table (recording revenue) to do that part in MySql.

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• Hibernate / MySQL Bulk insert problem

  - by Marty Pitt

  I'm having trouble getting Hibernate to perform a bulk insert on MySQL. I'm using Hibernate 3.3 and MySQL 5.1 At a high level, this is what's happening: @Transactional public Set<Long> doUpdate(Project project, IRepository externalSource) { List<IEntity> entities = externalSource.loadEntites(); buildEntities(entities, project); persistEntities(project); } public void persistEntities(Project project) { projectDAO.update(project); } This results in n log entries (1 for every row) as follows: Hibernate: insert into ProjectEntity (name, parent_id, path, project_id, state, type) values (?, ?, ?, ?, ?, ?) I'd like to see this get batched, so the update is more performant. It's possible that this routine could result in tens-of-thousands of rows generated, and a db trip per row is a killer. Why isn't this getting batched? (It's my understanding that batch inserts are supposed to be default where appropriate by hibernate).

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• Hibernate inserting into join table

  - by Karl

  I got several entities. Two of them got a many-to-many relation. When I do a bigger operation on these entities it fails with this exception: org.hibernate.exception.ConstraintViolationException: could not insert collection rows: I execute the operation i a @Transactional context. I don't do any explicit flushing i my daos. The flush is triggered by a query. In the queue are 15 elements (all of the same structure). one of them always fails (but it's always a different one (I checked) and always at a different position). Does anybody have a hint for me for what I might do wrong? My Mapping: @ManyToMany(targetEntity = CategoryImpl.class) protected Set<Category> categories = new HashSet<Category>();

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• What is an Enterprise Java Bean really?

  - by HDave

  On the Tomcat FAQ it says: "Tomcat is not an EJB server. Tomcat is not a full J2EE server." But if I: use Spring to supply an application context annotate my entities with JPA annotations (and use Hibernate as a JPA provider) configure C3P0 as a connection pooling data source annotate my service methods with @Transactional (and use Atomikos as JTA provider) Use JAXB for marshalling and unmarshalling and possibly add my own JNDI capability then don't I effectively have a JEE application server? And then aren't my beans EJBs? Or is there some other defining characteristic? What is it that a JEE compliant app server gives you that you can't easily/readily get from Tomcat with some 3rd party subsystems?

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• One account, multiple users, multiple shopping cart in a web application

  - by lemotdit

  I received a somewhat unusual request (imo) for a transactional web site. I have to implement the possibility of having multiple shopping cart for the same user. Those really are shopping carts, not order templates. I.E: A store with several departments ordering under the same account, but with a different person placing orders for a specific department only. Having more than one user per account is not an option since it would involve 'too much' management from the stores owner and the admins. Anyone had to deal with this before? The option so far is to have names for shopping cart, and a dropdown list or something alike after login to choose the cart with some kind of 'busy flag' to lock the cart if it's in use in another session.

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• Clojure for a lisp illiterate

  - by dbyrne

  I am a lifelong object-oriented programmer. My job is primarily java development, but I have experience in a number of languages. Ruby gave me my first real taste of functional programming. I loved the features Ruby borrowed from the functional paradigm such as closures and continuations. Eventually, I graduated to Scala. This has been a great way to gradually learn to approach non-trivial problems in a functional manner. Now I am interested in Clojure. I know all the sexy features that make it enticing (software transactional memory, macros, etc.), but I just can't get used to "thinking in lisp". I've seen Rich Hickey's screencasts aimed at java programmers, but they are geared towards explaining language features and not approaching real world problems. I am looking for any advice or resources which have made this transition easier for others.

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• Grails Services / Transactions / RuntimeException / Testing

  - by Rob

  I'm testing come code in a service with transactional set to true , which talks to a customer supplied web service the main part of which looks like class BarcodeService { .. /// some stuff ... try{ cancelBarCodeResponse = cancelBarCode(cancelBarcodeRequest) } catch(myCommsException e) { throw new RuntimeException(e) } ... where myCommsException extends Exception .. I have a test which looks like // As no connection from my machine, it should fail .. shouldFailWithCause(RuntimeException){ barcodeServices.cancelBarcodeDetails() } The test fails cause it's catching a myCommsException rather than the RuntimeException i thought i'd converted it to .. Anyone care to point out what i'm doing wrong ? Also will the fact that it's not a RuntimeException mean any transaction related info done before my try/catch actually be written out rather than thrown away ?? Thanks

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• What is Java Message Service (JMS) for?

  - by Daniel

  I am currently evaluating JMS and I don't get what I could use it for. Currently, I believe this would be a Usecase: I want to create a SalesInvoice PDF and print it when an SalesOrder leaves the Warehouse, so during the Delivery transaction I could send a transactional print request which just begins when the SalesOrder transaction completes successfully. Now I found out most JMS products are standalone server. Why would a need a Standalone Server for Message Processing, vs. e.g. some simple inproc processing with Quartz scheduler? How does it interact with my application? Isn't it much too slow? What are Usecases you already implemented successfully?

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• Set Hibernate session's flush mode in Spring

  - by glaz666

  I am writing integration tests and in one test method I'd like to write some data to DB and then read it. @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = {"classpath:applicationContext.xml"}) @TransactionConfiguration() @Transactional public class SimpleIntegrationTest { @Resource private DummyDAO dummyDAO; /** * Tries to store {@link com.example.server.entity.DummyEntity}. */ @Test public void testPersistTestEntity() { int countBefore = dummyDAO.findAll().size(); DummyEntity dummyEntity = new DummyEntity(); dummyDAO.makePersistent(dummyEntity); //HERE SHOULD COME SESSION.FLUSH() int countAfter = dummyDAO.findAll().size(); assertEquals(countBefore + 1, countAfter); } } As you can see between storing and reading data, the session should be flushed because the default FushMode is AUTO thus no data can be actually stored in DB. Question: Can I some how set FlushMode to ALWAYS in session factory or somewhere else to avoid repeating session.flush() call? All DB calls in DAO goes with HibernateTemplate instance. Thanks in advance.

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• How to research unmanaged memory leaks in .NET?

  - by Brandon

  I have a WCF service running over MSMQ. Memory gradually increases over time, indicating that there is some sort of memory leak. I ran the service locally and monitored some counters using PerfMon. Total CLR memory managed heap bytes remains relatively constant, while the process' private bytes increases over time. This leads me to believe that there is some sort of unmanaged memory leak. Assuming that unmanaged memory leak is the issue, how do I address the issue? Are there any tools I could use to give me hints as to what is causing the unmanaged memory leak? Also, all my service is doing is reading from the transactional queue and writing to a database, all as part of a DTC transaction (handled under the hood by requiring a transaction on the service contract). I am not doing anything explicitly with COM or DllImports. Thanks in advance!

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• [PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute query]

  - by doniyor

  i need help. i am trying to select from database thru sql statement in play framework, but it gives me error, i cannot figure out where the clue is. here is the code: @Transactional public static Users findByUsernameAndPassword(String username, String password){ String hash = DigestUtils.md5Hex(password); Query q = JPA.em().createNativeQuery("select * from USERS where" + "USERNAME=? and PASSWORD=?").setParameter(1, username).setParameter(2, password); List<Users> users = q.getResultList(); if(users.isEmpty()){ return null; } else{ return users.get(0); here is the eror message: [PersistenceException: org.hibernate.exception.SQLGrammarException: could not execute query] can someone help me please! any help i would appreciate! thanks

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• GWT : NULL Session

  - by jidma

  I'm using spring4gwt in my project. I have the following login service implementation: @Service("loginService") public class LoginServiceImpl extends RemoteServiceServlet implements LoginService { @Override @Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class) public UserBean checkUser(String userName, String password) throws Exception { HttpSession httpSession = getThreadLocalRequest().getSession(); } } When i call the loginService.checkUser("test","test") (In hosted mode), I get a null pointer exception, as getThreadLocalRequest() returns NULL instead of the actual session. I didn't try in web mode yet. Why would I get a null session ? Does it have something to do with spring4gwt ? Thank you

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• The time-to-reach-queue has elapsed

  - by nieve

  I'm attempting to send a message to a remote private queue from an error queue with powershell. The code I use looks like this: $msg = $src_q.Peek() $msg.Label = GetLabelWithoutFailedQueue($msg) $msg.UseDeadLetterQueue = $true $msg.UseTracing = $true $msg.AcknowledgeType = [System.Messaging.AcknowledgeTypes]::NegativeReceive $msg.TimeToBeReceived = [System.TimeSpan]::FromSeconds(10) $msg.TimeToReachQueue = [System.TimeSpan]::FromSeconds(10) $tx = new-object System.Messaging.MessageQueueTransaction $tx.Begin() $dest_q.Send($msg, $tx) $tx.Commit() The message keeps on appearing on the transactional dead letter queue with the class: "The time-to-reach-queue has elapsed." Anyone's got any idea what could trigger such an error? The queue definitely exists- I do manage to peek it. Also, the reason I get the message from the error queue by peeking is just for testing purposes; I have tried doing the same thing with Receive and the result is the same.

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• Reset JPA generated value between tests

  - by Rythmic

  I'm running spring + hibernate + JUnit with springJunit4runner and transactional set to default rollback I'm using in-memory derbydb as Database. Hibernate is used as a JPA Provider and I am successfully testing CRUD kinds of stuff. However, I have a problem with JPA and the behaviour of @GeneratedValue If I run one of my tests in isolation, two entitys are persisted with id 1 and 2. If i run the whole test suite the ids are instead 6 and 7. Spring does rollbacks just fine so there are only these two entitys in the database after addition and of course zero before. But behaviour of @GeneratedValue doesn't allow me to reliable findById unless I would return the Id from the dao.add(Entity e) //method I don't feel like doing that for the sake of testing, or is it a good practise to return the entity that was persisted so I should be doing it anyway?

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• What's the simplest way to provide a portable, locally running webservice server application?

  - by derFunk

  We have a bigger website running that offers a JsonRpc web service. For offline demonstration purposes I want to realize a portable, locally running webserver with a minimalistic feature replication of the live webservice, and bundle this together with Html files which do Ajax requests to it. This local server executable should have as little dependencies as possible. It's gonna be run and presented by non-devs on non-dev Windows machines, so I would prefer having a simple executable plus the service code - whereas language doesn't matter as long as it is .NET, PHP or Java. I'll need a small database behind which probably will be Sqlite. It's important to say that for some reasons we cannot use the original web service code, but we have to rewrite it new for the local demo server, this is why I want to put minimal effort in the local server tech. An installer for distribution is not mandatory, it's okay to have a zip file with an executable in it which starts up the local webserver. What would you recommend realizing these requirements? I've done some research already, but would love to here your opinions and get some pointers!

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• Sequence Number in testing Spring application with JUnit (Hibernating, Spring MVC)

  - by MBK

  I am testing DAO in Spring Application. @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = "classpath:/applicationContext.xml") @TransactionConfiguration(transactionManager = "transactionManager", defaultRollback = true) @Transactional public class CommentDAOImplTest { @Autowired //testing mehods here} The tests are running good. Iam able to add an comment and I also have a defaultRollback property set. So, the added comment will be deleted automatically. happy!..Now the problem is with the sequence number for mcomment. Can I, in any way rollback the seq number? any suggestins on that. I dont want to mess up the sequrnce number. Business requires comment Id to be showed. (I still dont know why). I know in memory db is an option....but I am guessing defaultRollback purpose is to eliminate in memory db testing and mocking. (Just my opinion.)

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• SQL Server - how to determine if indexes aren't being used?

  - by rwmnau

  I have a high-demand transactional database that I think is over-indexed. Originally, it didn't have any indexes at all, so adding some for common processes made a huge difference. However, over time, we've created indexes to speed up individual queries, and some of the most popular tables have 10-15 different indexes on them, and in some cases, the indexes are only slightly different from each other, or are the same columns in a different order. Is there a straightforward way to watch database activity and tell if any indexes are not hit anymore, or what their usage percentage is? I'm concerned that indexes were created to speed up either a single daily/weekly query, or even a query that's not being run anymore, but the index still has to be kept up to date every time the data changes. In the case of the high-traffic tables, that's a dozen times/second, and I want to eliminate indexes that are weighing down data updates while providing only marginal improvement.

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• SQL SERVER – WRITELOG – Wait Type – Day 17 of 28

  - by pinaldave

  WRITELOG is one of the most interesting wait types. So far we have seen a lot of different wait types, but this log type is associated with log file which makes it interesting to deal with. From Book On-Line: WRITELOG Occurs while waiting for a log flush to complete. Common operations that cause log flushes are checkpoints and transaction commits. WRITELOG Explanation: This wait type is usually seen in the heavy transactional database. When data is modified, it is written both on the log cache and buffer cache. This wait type occurs when data in the log cache is flushing to the disk. During this time, the session has to wait due to WRITELOG. I have recently seen this wait type’s persistence at my client’s place, where one of the long-running transactions was stopped by the user causing it to roll back. In the future, I will see if I could re-create this situation once again on my machine to validate the relation. Reducing WRITELOG wait: There are several suggestions to reduce this wait stats: Move Transaction Log to Separate Disk from mdf and other files. Avoid cursor-like coding methodology and frequent committing of statements. Find the most active file based on IO stall time based on the script written over here. You can also use fn_virtualfilestats to find IO-related issues using the script mentioned over here. Check the IO-related counters (PhysicalDisk:Avg.Disk Queue Length, PhysicalDisk:Disk Read Bytes/sec and PhysicalDisk :Disk Write Bytes/sec) for additional details. Read about them over here. There are two excellent resources by Paul Randal, I suggest you understand the subject from those videos. The links to videos are here and here. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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