PHP 7.0.0 RC 2 Released


(PHP 4, PHP 5)

mysql_free_resultLibera um resultado da memória


bool mysql_free_result ( resource $result )

mysql_free_result() irá liberar toda a memória associada ao identificador de resultado result.

mysql_free_result() apenas precisa ser chamada se você esta preocupado sobre quanta memória esta sendo usada em consultas que retornam grandes conjuntos de resultados. Toda a memória associada a um resultado é automaticamente liberada ao final da execução do script.



The result resource that is being evaluated. This result comes from a call to mysql_query().

Valor Retornado

Retorna TRUE em caso de sucesso ou FALSE em caso de falha.

Se não for usado um recurso para result, um erro de nível E_WARNING será emitido. É importante notar que mysql_query() apena retorna um resource para consultas SELECT, SHOW, EXPLAIN, e DESCRIBE.


Exemplo #1 Um exemplo mysql_free_result()

mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!
$result) {
'Não foi possível executar a consulta: ' mysql_error();
/* Use the result, assuming we're done with it afterwords */
$row mysql_fetch_assoc($result);

/* Now we free up the result and continue on with our script */




Para compatibilidade com versões anteriores, o seguinte apelido obsoleto pode ser usado: mysql_freeresult()

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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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