(PHP 4, PHP 5)

mysql_free_resultLibera la memoria occupata dal risultato


bool mysql_free_result ( resource $risultato )

mysql_free_result() libera utuuta la memoria associata all'identificativo del risultato risultato.

mysql_free_result() deve essere richiamata solo se si è preoccupati sulla quantità di memoria usata dalle query che restituiscono dei grandi risultati. Tutta la memoria associata al risultato è automaticamente liberata al termine dell'esecuzione dello script.

Restituisce TRUE in caso di successo, FALSE in caso di fallimento.

Per motivi di compatibilità con il passato, anche mysql_freeresult() può essere usata. Questo comunque è sconsigliato.

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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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