Which of the following describes how READ LOCAL locking works?

The correct answer is B. It locks a table for reading but allows concurrent inserts. Locks a table for reading, but allows concurrent inserts. A concurrent insert is an exception to the "readers block writers" principle. It applies only to MyISAM tables. If a MyISAM table has no holes in the middle resulting from deleted or updated records, inserts always take…

MySQL Locking

Question

Options

AIt locks a table for reading only by connections on localhost.
BIt locks a table for reading but allows concurrent inserts.
CIt locks a table for writing, preventing reads until it is released.

How the community answered

(50 responses)

A
12% (6)
B
80% (40)
C
8% (4)

Explanation

Locks a table for reading, but allows concurrent inserts. A concurrent insert is an exception to the "readers block writers" principle. It applies only to MyISAM tables. If a MyISAM table has no holes in the middle resulting from deleted or updated records, inserts always take place at the end of the table. In that case, a client that is reading from a table can lock it with a READ LOCAL lock to allow other clients to insert into the table while the client holding the read lock reads from it. If a MyISAM table does have holes, you can remove them by using OPTIMIZE TABLE to defragment

Topics

#READ LOCAL lock#concurrent inserts#table locks#MyISAM

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