International PHP Conference 2015


(PHP 4, PHP 5)

mysql_free_resultLibera la memoria del resultado


Esta extensión fue declarada obsoleta en PHP 5.5.0 y eliminada en PHP 7.0.0. En su lugar debería utilzarse las extensiones MySQLi o PDO_MySQL. Véase también la guía MySQL: elegir una API y sus P+F relacionadas para más información. Alternatives to this function include:


bool mysql_free_result ( resource $result )

mysql_free_result() liberará toda la memoria asociada con el identificador del resultado result.

mysql_free_result() solo necesita ser llamado si se está preocupado por la cantidad de memoria que está siendo usada por las consultas que devuelven conjuntos de resultados grandes. Toda la memoria de resultados asociada se liberará automaticamente al finalizar la ejecución del script.



El resultado resource que está siendo evaluado. Este resultado proviene de una llamada a mysql_query().

Valores devueltos

Devuelve TRUE en caso de éxito o FALSE en caso de error.

Si se utiliza un recurso no válido para result, se emitirá un error de nivel E_WARNING. Vale la pena señalar que mysql_query() solo devuelve un recurso para las consultas SELECT, SHOW, EXPLAIN, y DESCRIBE.


Ejemplo #1 Un ejemplo de mysql_free_result()

mysql_query("SELECT id, email FROM people WHERE id = '42'");
if (!
$resultado) {
'No se pudo ejecutar la consulta: ' mysql_error();
/* Usamos el resultado, asumiendo que, acto seguido, hemos terminado con él */
$fila mysql_fetch_assoc($resultado);

/* Ahora liberamos el resultado y continuamos con nuestro script */




Por razones de compatibilidad con versiones anteriores, los siguientes alias obsoletos podrían usarse: mysql_freeresult()

Ver también

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User Contributed Notes 7 notes

webmaster at bluesting dot co dot za
4 years ago
mysql_query() also returns a resource for "OPTIMIZE TABLE" statements!
Joachim Kruyswijk
10 years ago
Using this function may actually increase the amount of memory used. In my case, the script used 208 bytes less memory when *not* using mysql_free_result().
Check for yourself: call memory_get_usage() at the end of the script.
admin at ifyouwantblood dot de
7 years ago
yes this function may increase the memory usage if you use unbuffered querys and if you have not fetched all the data from mysql. in this case the mysql api has a problem: you want to free the result but do not want to close the connection. now mysql will only accept another query if all data has been fetched, so the api now must fetch the rest of the data when calling mysql_free_result().

so only use unbuffered querys if you fetch all the data (and need it).
8 years ago
If you're seeing warnings like "Warning: Unknown: 6 result set(s) not freed. Use mysql_free_result to free result sets which were requested using mysql_query() in Unknown on line 0" and want to turn them off, set mysql.trace_mode = Off in your php.ini
macronesia at macronesia dot net
10 years ago
You not need to use this if you are using PHP 4.

The comment below this comment may explain why it's actually costing more memory.
webmaster at wforums dot net
7 years ago
I agree with Joachim Kruyswijk (posted on 14-Jun-2005 11:42). I just did the test on my beta version of my new site (who needs to get dynamically news and user login from a database) and i use 1000kb less memory when i do not use mysql_free_result. I guess it is because the data it needs to load are not that large (for news: date, short description and for the user login: username, password). It may only be in the user control panel that it will be more, but since that isn't developed totally yet, i'll have to test :p
mdeininger at jyujin dot de
9 years ago
yes, i encountered that too. as far as i could tell, that's because the script is stored in memory after being compiled and that's as much more memory as it needs for a call to that function.

if you always get lotsa data in your results, using this function will decrease memory usage tho, unless you use non-buffered queries (which are preferable unless you absolutely *have* to use mysql_seek(), or you need to do another query while the last one hasn't finished reporting back, as they can provide a small speedup)
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