mysql_field_type
mysql_query() also returns a resource for "OPTIMIZE TABLE" statements!
mysql_free_result
(PHP 4, PHP 5)
mysql_free_result — 結果保持用メモリを開放する
警告
この拡張モジュールは PHP 5.5.0 で非推奨になりました。将来のバージョンで削除される予定です。 MySQLi あるいは PDO_MySQL を使うべきです。詳細な情報は MySQL: API の選択 や それに関連する FAQ を参照ください。 この関数の代替として、これらが使えます。
- mysqli_free_result()
NULLを PDO オブジェクトに代入、あるいは PDOStatement::closeCursor()
説明
bool mysql_free_result
( resource
$result
)
mysql_free_result() は、結果 ID result
に関するすべてのメモリを開放します。
mysql_free_result() は、 スクリプト実行のメモリの使用量が多すぎると懸念される場合にのみ 必要になります。指定した結果 ID に関する全ての結果保持用メモリは、 スクリプトの実行後に自動的に開放されます。
返り値
成功した場合に TRUE を、失敗した場合に FALSE を返します。
result がリソースではなかった場合、
E_WARNING レベルのエラーが発生します。
mysql_query() が resource
を返すのは SELECT, SHOW, EXPLAIN, そして DESCRIBE
の場合だけであることに注意しましょう。
例
例1 mysql_free_result() の例
<?php
$result = mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!$result) {
echo 'Could not run query: ' . mysql_error();
exit;
}
/* 結果を利用する。ここでは、その後結果を利用したものと仮定する */
$row = mysql_fetch_assoc($result);
/* 結果を開放し、さらにスクリプトの処理を進める */
mysql_free_result($result);
echo $row['id'];
echo $row['email'];
?>
注意
注意:
下位互換のために、次の非推奨別名を使用してもいいでしょう。 mysql_freeresult()
add a note
User Contributed Notes
mysql_free_result - [8 notes]
webmaster at bluesting dot co dot za ¶
2 years ago
mdeininger at jyujin dot de ¶
7 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)
Anonymous ¶
6 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
webmaster at wforums dot net ¶
4 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
admin at ifyouwantblood dot de ¶
5 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).
Nairebis ¶
7 years ago
ALWAYS use this function! I just encountered a bug in my code where I forgot to use this function. I also happen to be using mysql_pconnect() for a persistent connection. If you forget to free the result, it can hold the old result set open indefinitely within the HTTP process.
The upshot (in my application) was that I did updates that happened in a different HTTP process, but they mysteriously didn't show up in another HTTP process. After panicking that MySQL had mysterious data corruption and/or synchronization problems, I traced it back to this where an old result set was held open.
macronesia at macronesia dot net ¶
7 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.
Joachim Kruyswijk ¶
7 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.