MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
You can access the underlying InnoDB
table
(which is test.demo_test
by default) through
standard SQL interfaces. However, there are some restrictions:
When querying a table that is also accessed through the
memcached interface, remember that
memcached operations can be configured to
be committed periodically rather than after every write
operation. This behavior is controlled by the
daemon_memcached_w_batch_size
option. If this option is set to a value greater than
1
, use READ
UNCOMMITTED
queries to find rows that were just
inserted.
mysql>SET SESSSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
mysql>SELECT * FROM demo_test;
+------+------+------+------+-----------+------+------+------+------+------+------+ | cx | cy | c1 | cz | c2 | ca | CB | c3 | cu | c4 | C5 | +------+------+------+------+-----------+------+------+------+------+------+------+ | NULL | NULL | a11 | NULL | 123456789 | NULL | NULL | 10 | NULL | 3 | NULL | +------+------+------+------+-----------+------+------+------+------+------+------+
When modifying a table using SQL that is also accessed
through the memcached interface, you can
configure memcached operations to start a
new transaction periodically rather than for every read
operation. This behavior is controlled by the
daemon_memcached_r_batch_size
option. If this option is set to a value greater than
1
, changes made to the table using SQL
are not immediately visible to memcached
operations.
The InnoDB
table is either IS (intention
shared) or IX (intention exclusive) locked for all
operations in a transaction. If you increase
daemon_memcached_r_batch_size
and
daemon_memcached_w_batch_size
substantially from their default value of
1
, the table is most likely locked
between each operation, preventing
DDL statements on the table.