I am beginning to understand how transaction and locks work in databases. So in a very higher-level understanding: BEGIN -- txID: 1234 UPDATE tbl_1 SET field = value WHERE id IN (1); -- for simplicity -- Locks acquired on rows…
I'm making a Django app using a postgresql database for a family who need to coordinate their grocery purchases. Say one person has on their mobile device a full list of the groceries and is in the supermarket, buying and…
According to the PSQL docs on explicit locking: SELECT FOR UPDATE will wait for a concurrent transaction that has run any of those commands on the same row, and will then lock and return the updated row (or no row,…
Problem I need to setup Symfony framework.yaml parameter framework.lock with 2+ memcached servers using .env. But when I'm try to do so, it not recognize 2 servers, but only one and with glitch. Symfony lock docs: https://symfony.com/doc/current/lock.html What I have…
I want to migrate my app to clusters so I have to deal with mysql locking. For this post, I have simple table with 'id' and 'flag' whether is record updated or not. There are 3 threads reading table of…
mysql version is 8.0.26 and use REPEATABLE-READ. table: create table test ( id int auto_increment primary key, a varchar(256) null, b int null, c int null, create_time timestamp default CURRENT_TIMESTAMP null, constraint uni_key unique (a, b, c) ); init data:…
I have a simple table with an index on the count column | Counts | CREATE TABLE `Counts` ( `id` bigint NOT NULL, `count` int NOT NULL, PRIMARY KEY (`id`), KEY `count_i` (`count`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci | INSERT…
I got the following two functions that I use to lock a Redis key. I am trying to prevent concurrency execution of a block of code using Redis. So what I do is use the following functions in such a…
When iam trying to create lock using powershell Azure automation runbook by using below script New-AzResourceLock -LockName test -LockLevel CanNotDelete -ResourceGroupName rg -ResourceName resorcename -LockNotes Protection Auto created by Azure Backup -ResourceType Microsoft.Storage/storageAccounts -Force error getting: A positional parameter cannot…
Connection1: BEGIN; SELECT * FROM world.city WHERE ID = 130 FOR SHARE; Connection2: SELECT engine, thread_id, object_schema, object_name, lock_type, lock_mode, lock_status, lock_data FROM performance_schema.data_locks; +--------+-----------+---------------+-------------+-----------+---------------+-------------+-----------+ | engine | thread_id | object_schema | object_name | lock_type | lock_mode | lock_status |…