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What are the states of a binary lock?
A Binary lock has only two states: Locked or Unlocked. Other transactions cannot access locked items, not even for a read operation. Because of this restriction, binary locks are generally no longer used. When using this type of locking, a lock can be in one of three states: shared, exclusive or unlocked.
How do I stop a MySQL lock?
The following items describe some ways to avoid or reduce contention caused by table locking:
- Consider switching the table to the InnoDB storage engine, either using CREATE TABLE
- Optimize SELECT statements to run faster so that they lock tables for a shorter time.
- Start mysqld with –low-priority-updates .
What are the shared and exclusive locks in InnoDB?
Shared and Exclusive Locks InnoDB implements standard row-level locking where there are two types of locks, shared (S) locks and exclusive (X) locks. A shared (S) lock permits the transaction that holds the lock to read a row. An exclusive (X) lock permits the transaction that holds the lock to update or delete a row.
What is an insert intention lock in MySQL?
An insert intention lock is a type of gap lock set by INSERT operations prior to row insertion. This lock signals the intent to insert in such a way that multiple transactions inserting into the same index gap need not wait for each other if they are not inserting at the same position within the gap.
When do you not need gap locking in MySQL?
Gap locking is not needed for statements that lock rows using a unique index to search for a unique row. (This does not include the case that the search condition includes only some columns of a multiple-column unique index; in that case, gap locking does occur.)
How does the intention lock protocol work in SQL?
The intention locking protocol is as follows: Before a transaction can acquire a shared lock on a row in a table, it must first acquire an IS lock or stronger on the table. Before a transaction can acquire an exclusive lock on a row in a table, it must first acquire an IX lock on the table.