transactions

问题 I have a data file and from time to time I need to write a change to the file. The change consists of changing information in more than one place. For example, changing some data near the end of the file and also changing some information near the start. I want the two separate writes to either both succeed or both fail, otherwise it is left in uncertain state and effectively corrupted. Is there any builtin support for this scenario in .NET or in general? If not then how to others solve this

问题 I'm new to Spring and I'm not able to make the transaction propagation in "REQUIRED" mode. Here is an example: @Controller public class ExampleController { @Autowired Foo foo; @Autowired Bar bar; @RequestMapping(value = "/example") public String submitForm(Model model) throws Exception { User user = new User("Joe", "Bloggs"); user = foo.save(user); bar.simpleMethod(user); return "success"; } } @Repository public class Foo { // A JPA repository private EntityManager em; @Transactional

问题 I'm facing some locks at our DB server created by our application. What I don't understand is how a process that is Sleeping is having an Open Transaction (that process 71 is the one creating the Lock). As far as I know when a process finishes it closes all the opened transactions. Is that rigth? Thanks in advance mates. 回答1: As far as I know when a process finishes it closes all the opened transactions. Is that right? No. If you explicitly open a transaction you must explicitly commit or

问题 I'm trying to do insert via a native query with JPA, but I don't want to create a transaction: Query query = em.createNativeQuery("INSERT INTO person (id, firstname, lastname) VALUES ('1','Ronnie','Dio')"); int count = query.executeUpdate(); this ends up with the TransactionRequiredException: javax.persistence.TransactionRequiredException: Executing an update/delete query at org.hibernate.ejb.AbstractQueryImpl.executeUpdate(AbstractQueryImpl.java:99) However, if I unwrap the Hibernate session

问题 I'm doing a load test on user signup with the same email address for a webservice and the first 10 users which connect simultaneously will always register. I'm using WATCH and MULTI but that doesn't seem to work any way. I'm calling save() to save the user. this.insert = function(callback) { this.preInsert(); created = new Date(); updated = new Date(); // Also with these uncommented it still doesn't work // Common.client.watch("u:" + this.username); // Common.client.watch("em:" + this.email);

问题 I'm doing a load test on user signup with the same email address for a webservice and the first 10 users which connect simultaneously will always register. I'm using WATCH and MULTI but that doesn't seem to work any way. I'm calling save() to save the user. this.insert = function(callback) { this.preInsert(); created = new Date(); updated = new Date(); // Also with these uncommented it still doesn't work // Common.client.watch("u:" + this.username); // Common.client.watch("em:" + this.email);

问题 I've a very simple database with following schema: video (id, title, description) category (id, name) tag (id, name) video_category_reference (video_id, category_id) video_tag_reference(video_id, tag_id) abc_table (video_id, description, categories) The first five tables use InnoDB engine. The last table - abc_table uses MyISAM engine and it contains some kind of "cache". description column stores the result of CONCAT(video.title, video.description, GROUP_CONCAT(tag.name)) and categories

问题 I'm building the checkout page for an e-commerce site, and I have a fairly long transaction that creates a new User model and a new Order model. I wrapped the creation of these models in a transaction so that if validation for one fails, the other isn't hanging around in the database. Here's the trimmed-down code in my OrdersController: rescue_from ActiveRecord::Rollback, with: :render_new def render_new render action: 'new' end ActiveRecord::Base.transaction do @user = User.new params[:user]

问题 1: I was trying this and it was working fine: start transaction; select * from orders where id = 21548 LOCK IN SHARE MODE; update orders set amount = 1500 where id = 21548; commit; According to the definition of LOCK IN SHARE MODE , it locks the table with IS lock and lock the selected rows with S lock. When a row is locked with S lock.How can it be modified without releasing lock? It needs X lock to modify it.Right? Or is it valid only for different connection transaction? 2: //session1

问题 Tx is committed when : request success callback returns - that means that multiple requests can be executed within transaction boundaries only when next request is executed from success callback of the previous one when your task returns to event loop It means that if no requests are submitted to it, it is not committed until it returns to event loop. These facts pose 2 problematic states : placing a new IDB request by enqueuing a new task to event loop queue from within the success callback