The preparation and closing of prepared statements was sent to all servers
even though the execution was always sent to the master. With this change,
all queries which interact with prepared statements are only sent to the master.
The sending of statement preparations to all servers is a problem when a
statement which depends on a database or a table is created and the DDL
statement which created that table has not yet been replicated to the
slaves.
In addition to fixing the aforementioned problem, this change should also
reduce unnecessary network traffic to slaves and improve the overall
performance of the prepared statements.
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