phantom playbooks

0. IntroductionPlaybooks is the language of Ansible management configuration, deployment applications, and orchestration, and you can use playbooks to describe the policies you want to perform on the remote host or the set of steps that you perform.Similar to a set of task sets, defining information such as projects, organizational structures, profiles, and so on, the task is to organize the things you want to do in one step and the whole playbookOffi

Batch execution playbooksAnother way of remote batch command execution is to use playbooks;This is Playbooks's Official document: http://docs.ansible.com/playbooks.htmlHere are playbooks examples of ansible: https://github.com/ansible/ansible-examplesUsing the Ansbile API in PythonThe above methods of executing the Ansible module are called directly on the command line, and if further processing is required

Playbooks method (2nd chapter will explain). Ansible returns a clear indication of whether the operation was successful, whether there was a change, and the error message when it failed.The ansible task is usually performed in a playbooks manner, and in rare cases it is run in command-line mode. In the past, we used the ping module of ansible to check if the "Controlled node" was properly controlled. In fa

Preface Two previous articles talk about ansible deployment and use of ansible modules respectively. They have an initial understanding of ansible. This article focuses on introducing playbook.For details about ansible deployment, click ansible first: DeploymentAnsible module celebration: ansible Part 2: module usage Playbook Introduction Playbook is a list composed of one or more playbooks. Its main function is to merge roles defined by tasks into

transaction reads that uncommitted data cannot be read repeatedly: a transactionUpdate or deleteoperation, data inconsistency for another transaction two queries the Phantom reads: A transaction has been performed on the dataNew Action, the result of another transaction two queries is inconsistent. We see that non-repeatable reading is similar to Phantom reading, but in fact they are very different,non-rep

commits during the instance processing, so the same select may return different results. Repeatable Read (can be reread) This is the default transaction isolation level for MySQL, which ensures that multiple instances of the same transaction will see the same rows of data while concurrently reading the data. In theory, however, this can lead to another tricky problem: Phantom Reading (Phantom read). To pu

when necessary. This option works the same as setting HOLDLOCK on all tables in all SELECT statements within a transaction.Volatile data can is read but not modified, and no new data can addedDuring the transaction.Serializable = 0,//Summary: Repeatable read isolation levels, Phantom reads, locking all data used in queries to prevent other users from updating data, but other users can insert new phantom ro

define the meaning of the four isolation levels in the database theory, but will introduce to you how MySQL/InnoDB defines these four isolation levels. MySQL/InnoDB defines four isolation levels: Read UncommitedUncommitted records can be read. This isolation level is not used and ignored. Read Committed (RC)Snapshot read is ignored.For the current read,RC isolation level ensures locking (record lock) of read Records). Repeatable Read (RR)Snapshot read is ignored.For the current read, the RR

which the transaction deals with the data.In a typical application, multiple transactions run concurrently, often manipulating the same data to complete their work. Concurrency, though required, can cause problems: Dirty Reads (Dirty read)--dirty reads occur when a transaction reads data that has been overwritten by another transaction but has not yet been committed. If these changes are rolled back later, the data read by the first transaction will be invalid. Non-repeatable read

committed, transaction B queries out a uncommitted record. non-repeatable read (Non-repeatable Read): transaction A reads once, at which point the transaction B updates or deletes the data, and transaction a again queries for inconsistent data. Phantom Reading (Phantom Read): Transaction A reads once, at which point the transaction B inserts a data transaction a again query, more records.2. MySQL's underly

data row after the iteration is grouped 4. How does the process of inserting and deleting a data in MySQL database execute at the bottom?MySQL locks, locks are indexed, and row-level locks are index-based. InnoDB uses row-level locks only if the data is retrieved by index criteria, otherwise INNODB will use a table lock! The main points involved in the analysis are: (1) Where conditions are split (2) about the combination of index and transaction isolation level Reference: (1) MySQL transactio

Transactions are different from locks. Transactions have ACID properties:Atomicity: Persistence: Redo log Redo logs to ensure the atomicity and durability of transactions,Consistency: Undo log is used to ensure transactional consistencyIsolation: A transaction sees the results of other transactions, such as Phantom reads, during the operation. Locks are a mechanism for resolving isolation. The isolation level of a transaction is implemented through a

same rows of data while concurrently reading the data. In theory, however, this can lead to another tricky problem: Phantom Reading (Phantom read). To put it simply, Phantom reads when a user reads a range of data rows, another transaction inserts a new row within that range, and when the user reads the data row of that range, a new

or BEGIN statement can start a new transaction commit: Commit can commit the current transaction, is the change to a permanent change rollback: ROLLBACK canTo rollback the current transaction, cancel its change 2, directly using set to change the MySQL auto-commit mode MySQL default is automatically submitted, that is, you submit a query, it is directly executed!We can use set Autocommit=0 to disable autocommit set autocommit=1 turn on auto commit to implement transaction processing. But note t

transaction may have new commits during the instance processing, so the same select may return different results.repeatable Read (can be reread) This is the default transaction isolation level for MySQL, which ensures that multiple instances of the same transaction will see the same rows of data while concurrently reading the data. In theory, however, this can lead to another tricky problem: Phantom Reading (Phan