I tested using "fetch all" versus "while / fetch array" and :
fetch-all uses less memory (but not for so much).
In my case (test1 and test2): 147008,262848 bytes (fetch-all) versus 147112,262888 bytes (fetch-array & while.
So, about the memory, in both cases are the same.
However, about the performance
My test takes :350ms (worst case) using fetch-all, while it takes 464ms (worst case) using fetch-array, or about 35% worst using fetch array and a while cycle.
So, using fetch-all, for a normal code that returns a moderate amount of information is :
a) cleaner (a single line of code)
b) uses less memory (about 0.01% less)
c) faster.
php 5.6 32bits, windows 8.1 64bits
mysqli_result::fetch_all
mysqli_fetch_all
(PHP 5 >= 5.3.0, PHP 7)
mysqli_result::fetch_all -- mysqli_fetch_all — Fetches all result rows as an associative array, a numeric array, or both
설명
객체 기반 형식
절차식 형식
mysqli_fetch_all() fetches all result rows and returns the result set as an associative array, a numeric array, or both.
인수
-
result -
순차 형식 전용: mysqli_query()나 mysqli_store_result()나 mysqli_use_result()가 반환한 결과셋 식별자.
-
resulttype -
This optional parameter is a constant indicating what type of array should be produced from the current row data. The possible values for this parameter are the constants
MYSQLI_ASSOC,MYSQLI_NUM, orMYSQLI_BOTH.
반환값
Returns an array of associative or numeric arrays holding result rows.
MySQL Native Driver Only
mysqlnd에서만 사용할 수 있습니다.
As mysqli_fetch_all() returns all the rows as an array in a single step, it may consume more memory than some similar functions such as mysqli_fetch_array(), which only returns one row at a time from the result set. Further, if you need to iterate over the result set, you will need a looping construct that will further impact performance. For these reasons mysqli_fetch_all() should only be used in those situations where the fetched result set will be sent to another layer for processing.
참고
- mysqli_fetch_array() - Fetch a result row as an associative, a numeric array, or both
- mysqli_query() - Performs a query on the database
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User Contributed Notes 5 notes
jcastro at eftec dot cl ¶
9 years ago
mail2magvay at rambler dot ru ¶
5 years ago
By the way, this case pretty work's too:
$services = $mysqli->query("SELECT * FROM table1");
if($services && $services->num_rows>0){
$services->fetch_all(MYSQLI_ASSOC);
}
foreach($services as $service){
echo $service; //work properly, cause it implements Iterator
}
That's mean in this case $services is a valid array (or empty array)
m dot amiot at otak-arts dot com ¶
12 years ago
If you really need this function, you can just extend the mysqli_result class with a function like this one.
<?php
public function fetch_all($resulttype = MYSQLI_NUM)
{
if (method_exists('mysqli_result', 'fetch_all')) # Compatibility layer with PHP < 5.3
$res = parent::fetch_all($resulttype);
else
for ($res = array(); $tmp = $this->fetch_array($resulttype);) $res[] = $tmp;
return $res;
}
?>
darek334 at gazeta dot pl ¶
1 year ago
be careful fetch_all(MYSQLI_ASSOC ) returns an array in the form
<?php
array(0 => array(...row...), 1 => array(...row...) .... ), even if is one row...
?>
not compared to fetch_assoc() which returns one array of the result in form:
<?php
array(...row...)
?>
andrey at php dot net ¶
14 years ago
Return value changed in 5.3.3 - between 5.3.0 and 5.3.2 (incl.) when the result set was empty NULL was returned. 5.3.3+ returns an empty array.
Also, mysqli_fetch_all works only for buffered result sets, which are the default for mysqli_query. MYSQLI_USE_RESULT will be supported in 5.3.4+
However, it makes little sense to use it this way, materialising unbuffered sets. In this case choose STORE_RESULT, and fetch_all won't copy the data, but reference it, as it is stored already in mysqlnd.
