pessimistic-locking

问题 I want to lock my table, but it didn't work. How can I handle it? Appreciate any advice! Typescript Typeorm Postgres //src public async checkDBTable(builderAddress: string): Promise<boolean> { // 1. find DB table by key(builderAddress) // 2. return true({key: value} exist) or false const info: InfoEntity|undefined = await this.findOne(builderAddress, { lock: {mode: 'pessimistic_write'} }); return nonceInfo !== undefined; } //result error: PessimisticLockTransactionRequiredError: An open

问题 I have started using spring from last few months and I have a question on transactions. I have a java method inside my spring batch job which first does a select operation to get first 100 rows with status as 'NOT COMPLETED' and does a update on the selected rows to change the status to 'IN PROGRESS'. Since I'm processing around 10 million records, I want to run multiple instances of my batch job and each instance has multiple threads. For a single instance, to make sure two threads are not

问题 i'm trying to figure out how to use/test the lockforupdate correctly, but i found is not function like what i expected this is just testing public function index() { return dd(\DB::transaction(function() { if (\Auth::guard('user')->check()) { $model = \App\Models\User::find(1)->lockForUpdate(); sleep(60); $model->point = 100000; $model->save(); } else { $model = \App\Models\User::find(1); $model->point = 999; $model->save(); } return $model; })); } i try to test in 2 browser, browser 1 user

问题 i'm trying to figure out how to use/test the lockforupdate correctly, but i found is not function like what i expected this is just testing public function index() { return dd(\DB::transaction(function() { if (\Auth::guard('user')->check()) { $model = \App\Models\User::find(1)->lockForUpdate(); sleep(60); $model->point = 100000; $model->save(); } else { $model = \App\Models\User::find(1); $model->point = 999; $model->save(); } return $model; })); } i try to test in 2 browser, browser 1 user

问题 How do we specify LockMode in EJB3 Persistence NamedQuery? I want to add Pessimistic LockMode to my existing select so that I can update if necessary but surprisingly Query object doesnot have setLockMode(xxx) method ( My understanding was if JPA, asubset of EJB3 persistence, exposes setLockMode, EJB3 persistence should have the method available too). Query query = em.createNamedQuery("findOptoutStudent"); query.setParameter("optoutIndicator", optoutIndicator); List<Student> students = query

问题 How to implement pessimistic locking in a php/mysql web application? web-user opens a page to edit one dataset (row) web-user clicks on the button "lock", so other users are able to read but not to write this dataset web-user makes some modifications (takes maybe 1 to 30 minutes) web-user clicks "save" or "cancel" and the "lock" is removed Are there standard methods in php/mysql for this scenario? What happens if the web-user never clicks on "save"/"cancel" but closes the internet-exploror?

问题 I want explicitly provide an order on how MySql InnoDB should acquire locks for rows. If this is possible there shouldn't be any dead locks just stalling. (If we follow the convention.) First, the databse should lock all rows found in table "models" in ascending order. Then all rows in the second table "colors" should get locked in ascending order. Is there a way to control the database to lock table "models" first and then "colors"? Given for example: start transaction; select * from models

问题 I've been thinking about developing some simple record locking for an application I'm involved in. There are a few users who will take literally hours to complete an edit of a record. This causes issues when someone else wants to make a change to the record. Currently there is no locking involved. I'm not certain that Optimistic locking is reliable in my case, as the record is saved thru an AJAX request. I'm looking at applying some kind of Pessimistic Locking; using two fields, such as,

问题 I have an ASP.Net webpage where the user selects a row for editing. I want to use the row lock on that row and once the user finishes the editing and updates another user can edit that row i.e. How can I use rowlock so that only one user can edit a row? Thank you 回答1: You can't lock a row like that using DB engine locks. Most other strategies would rely on keeping the connection open (such as sp_getapplock) and this is nonsensical in web apps. Even if you set a flag on the row, what happens

问题 I'm trying to implement some kind of semaphores for cron jobs that runs in different JBoss nodes. I'm trying to use the database (Oracle 11g) as a locking mechanism using one table to syncronize the cron jobs in the different nodes. The table is very simple: CREATE TABLE SYNCHRONIZED_CRON_JOB_TASK ( ID NUMBER(10) NOT NULL, CRONJOBTYPE VARCHAR2(255 Byte), CREATIONDATE TIMESTAMP(6) NOT NULL, RUNNING NUMBER(1) ); ALTER TABLE SYNCHRONIZED_CRON_JOB_TASK ADD CONSTRAINT PK_SYNCHRONIZED_CRON_JOB_TASK