Analysis:
--------
OPTIMIZE TABLE on INNODB or PARTITIONED INNODB tables
doesn't allow concurrent changes to the same table, thus
causing down time in user applications.

OPTIMIZE TABLE for INNODB or PARTITIONED INNODB tables
uses ALTER TABLE FORCE operation internally to address
the fragmentation problem. This operations involves a table
copy and taking a strong lock on SQL-layer which blocks
all concurrent changes to the table. The downtime is high
while performing the operation for large tables.

Fix:
----
MySQL supports online rebuilding of tables within the storage
engine for INNODB or PARTITIONED INNODB tables starting from
MySQL 5.6.4. With this patch, the operations listed below
will trigger online rebuild of table.
a) OPTIMIZE TABLE.
b) ALTER TABLE FORCE and
c) ALTER TABLE ENGINE= INNODB(Same engine during creation)

The online rebuild involves taking strong lock only for
brief interval of time thus reducing the downtime for
the operations. Concurrent changes to the table are
allowed and the time taken to complete the operation
is reduced considerably.

Note that these operations will continue to use table
copy under any of the below conditions:
a) 'old_alter_table' system variable is turned ON.
b) 'skip-new' mysqld option is enabled and OPTIMIZE
    TABLE operation is performed.
c) Algorithm COPY is explicitly specified for the
   ALTER TABLE operations.