PHP 5.6.0beta1 released


(PECL mysqlnd_ms >= 1.0.0)

mysqlnd_ms_query_is_selectFind whether to send the query to the master, the slave or the last used MySQL server


int mysqlnd_ms_query_is_select ( string $query )

Finds whether to send the query to the master, the slave or the last used MySQL server.

The plugins built-in read/write split mechanism will be used to analyze the query string to make a recommendation where to send the query. The built-in read/write split mechanism is very basic and simple. The plugin will recommend sending all queries to the MySQL replication master server but those which begin with SELECT, or begin with a SQL hint which enforces sending the query to a slave server. Due to the basic but fast algorithm the plugin may propose to run some read-only statements such as SHOW TABLES on the replication master.



Query string to test.


A return value of MYSQLND_MS_QUERY_USE_MASTER indicates that the query should be send to the MySQL replication master server. The function returns a value of MYSQLND_MS_QUERY_USE_SLAVE if the query can be run on a slave because it is considered read-only. A value of MYSQLND_MS_QUERY_USE_LAST_USED is returned to recommend running the query on the last used server. This can either be a MySQL replication master server or a MySQL replication slave server.

If read write splitting has been disabled by setting mysqlnd_ms.disable_rw_split, the function will always return MYSQLND_MS_QUERY_USE_MASTER or MYSQLND_MS_QUERY_USE_LAST_USED.


Beispiel #1 mysqlnd_ms_query_is_select() example

function is_select($query)
 switch (
printf("'%s' should be run on the master.\n"$query);
printf("'%s' should be run on a slave.\n"$query);
printf("'%s' should be run on the server that has run the previous query\n"$query);
printf("No suggestion where to run the '%s', fallback to master recommended\n"$query);

is_select("INSERT INTO test(id) VALUES (1)");
is_select("SELECT 1 FROM DUAL");

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

INSERT INTO test(id) VALUES (1) should be run on the master.
SELECT 1 FROM DUAL should be run on a slave.
/*ms=last_used*/SELECT 2 FROM DUAL should be run on the server that has run the previous query

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