gistfile1.txt

#!/usr/bin/env php
<?php
$pdo = new PDO("mysql:host=127.0.0.1;dbname=plhw_application_api_development", 'plhwapi_dev', 'xxxxxxxxxxx');

$pdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
print memory_get_usage() . PHP_EOL;
$uresult = $pdo->query("SELECT * FROM event_stream event_stream ORDER BY created_at ASC, version ASC");
print memory_get_usage() . PHP_EOL;

//outputs
$ ./bin/test.php 
364584
329469336

//

gistfile2.txt

$sql = "SELECT * FROM event_stream event_stream ORDER BY created_at ASC, version ASC";
$pdo = new PDO("mysql:host=127.0.0.1;dbname=plhw_application_api_development", 'plhwapi_dev', 'xxxxxxxxxxx', []);
$pdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);


function generator($pdo, $sql)
{
    $stmt = $pdo->prepare($sql);
    $stmt->execute();
    while ($rs = $stmt->fetch(\PDO::FETCH_OBJ)) {
        yield $rs;
    }
}

print memory_get_usage() . PHP_EOL;
$result  = generator($pdo, $sql);
print memory_get_usage() . PHP_EOL;
foreach ($result as $row) {

}
print memory_get_usage() . PHP_EOL;

//outputs
$ ./bin/test.php
365424
369936
370288


function generator($pdo, $sql)
{
    $stmt = $pdo->prepare($sql);
    $stmt->execute();
    print memory_get_usage() . PHP_EOL; // <-- add this line
    while ($rs = $stmt->fetch(\PDO::FETCH_OBJ)) {
        yield $rs;
    }
}

print memory_get_usage() . PHP_EOL;
$result  = generator($pdo, $sql);
print memory_get_usage() . PHP_EOL;
foreach ($result as $row) {

}
print memory_get_usage() . PHP_EOL;

$ ./bin/test.php
362608
367120
329471936
367472

gistfile3.txt

$sql = "SELECT * FROM event_stream event_stream ORDER BY created_at ASC, version ASC";
$pdo = new PDO("mysql:host=127.0.0.1;dbname=plhw_application_api_development", 'plhwapi_dev', 'xxxxxxxxxxx', []);
$pdo->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);

print memory_get_usage() . PHP_EOL;
$stmt = $pdo->prepare($sql);
$stmt->execute();
print memory_get_usage() . PHP_EOL;
while ($rs = $stmt->fetch(\PDO::FETCH_OBJ)) {

}
print memory_get_usage() . PHP_EOL;

//outputs
$ ./bin/test.php
364520
329469272
329469272