Contents
Is the mysql table lock aware of InnoDB?
InnoDB is aware of table locks if innodb_table_locks = 1 (the default) and autocommit = 0, and the MySQL layer above InnoDB knows about row-level locks. Otherwise, InnoDB ‘s automatic deadlock detection cannot detect deadlocks where such table locks are involved.
How are locks set in MySQL 5.7 reference manual?
A locking read, an UPDATE, or a DELETE generally set record locks on every index record that is scanned in the processing of the SQL statement. It does not matter whether there are WHERE conditions in the statement that would exclude the row. InnoDB does not remember the exact WHERE condition, but only knows which index ranges were scanned.
Why does InnoDB not remember the exact where condition?
InnoDB does not remember the exact WHERE condition, but only knows which index ranges were scanned. The locks are normally next-key locks that also block inserts into the “gap” immediately before the record. However, gap locking can be disabled explicitly, which causes next-key locking not to be used.
What are the settings for InnoDB autoinc lock mode?
There are three possible settings for the innodb_autoinc_lock_mode variable. The settings are 0, 1, or 2, for “traditional”, “consecutive”, or “interleaved” lock mode, respectively. innodb_autoinc_lock_mode = 0 (“traditional” lock mode)
What are the locks in MySQL 8.0 reference manual?
MySQL 8.0 Reference Manual / / A locking read, an UPDATE, or a DELETE generally set record locks on every index record that is scanned in the processing of an SQL statement. It does not matter whether there are WHERE conditions in the statement that would exclude the row.
How are locks set in MySQL transaction isolation?
FROM is a consistent read, reading a snapshot of the database and setting no locks unless the transaction isolation level is set to SERIALIZABLE. For SERIALIZABLE level, the search sets shared next-key locks on the index records it encounters.