reach memory limit with loop inside loop inside loop - php

Question

Disclaimer: I am aware that I have in my code deprecated mysql functions. That is on my todo list.
I have a MySql select giving me seasons for diferent items in a house booking system.
Kind of:
Low season: 2010-01-01, 2010-03-01, 100 //meaning start,end,price
This comes in my first sql:
while($season_row=mysql_fetch_assoc($season_res)){
$seasonsArray[$season_row['id_item']][] = array(
$season_row['season_start'],
$season_row['season_end'],
$season_row['daily_price']
);
}
The dates are defined here (arriving to the function as YYYY-mm-dd):
function seasonPrice($from,$to,$requested_item){
$start = round(strtotime($from)/86400)*86400; // like 2008-01-01
$end = round(strtotime($to)/86400)*86400; // to 2015-01-01
$formattedStart = date('Y-m-d', $start);
$formattedEnd = date('Y-m-d', $end);
Now I need to loop between 2 dates, between the items of the $seasonsArray and then check the price of that item in that specific day.
I did this with:
foreach($seasonsArray as $item=>$value){
for( $thisDay = $start; $thisDay < $end; $thisDay = $thisDay + 86400){
foreach($value as $innerValue){
$season_start = roundToSeconds($innerValue[0]);
$season_end = roundToSeconds($innerValue[1]);
if($thisDay >= $season_start && $thisDay <= $season_end) {
$foundPrice[] = round($innerValue[2]);
}
}
$thisSerie[] = array($thisDay * 1000, isset($foundPrice) ? $foundPrice[0] : 0);
// security check to avoid double assigned seasons to same day
if(count($foundPrice) > 1){ die('There is double bookings in item: '.$item);}
unset($foundPrice);
}
$seasonPrices[] = array(
'data'=> $thisSerie,
'label'=> 'House ID: '.$item,
);
}
But I get: Fatal error: Allowed memory size of 100663296 bytes exhausted
Any suggestion on where my code can be improved to not need so much memory? Or is there a bug and I don't see it?

Answer 1

I'd generate a range of days and join against your seasons table, and use a single query to get the desired resulset, e.g.:
SELECT dates.Date,
coalesce(s.price, 0) AS price
FROM
(SELECT a.Date
FROM
( SELECT curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY AS Date, '0' AS price
FROM
(SELECT 0 AS a
UNION ALL SELECT 1
UNION ALL SELECT 2
UNION ALL SELECT 3
UNION ALL SELECT 4
UNION ALL SELECT 5
UNION ALL SELECT 6
UNION ALL SELECT 7
UNION ALL SELECT 8
UNION ALL SELECT 9) AS a
CROSS JOIN
(SELECT 0 AS a
UNION ALL SELECT 1
UNION ALL SELECT 2
UNION ALL SELECT 3
UNION ALL SELECT 4
UNION ALL SELECT 5
UNION ALL SELECT 6
UNION ALL SELECT 7
UNION ALL SELECT 8
UNION ALL SELECT 9) AS b
CROSS JOIN
(SELECT 0 AS a
UNION ALL SELECT 1
UNION ALL SELECT 2
UNION ALL SELECT 3
UNION ALL SELECT 4
UNION ALL SELECT 5
UNION ALL SELECT 6
UNION ALL SELECT 7
UNION ALL SELECT 8
UNION ALL SELECT 9) AS c) a
WHERE a.Date BETWEEN '$from' AND '$to'
ORDER BY a.Date) dates
LEFT JOIN seasons s ON dates.Date BETWEEN s.start AND s.END
The complicated inner query avoids the creation of a temp table (taken from generate days from date range) and works for up to 1000 days, but creating a temp table would be fine.

Answer 2

It looks to be like you are never leaving the for loop. Where do $start and $end get set. Verify their values by printing them out.
As far as optimization, there is no need to be looping through each day. Skip the for loop that counts days and use $season_start and $season_end to calculate the day in the second foreach loop.
In fact, there is a bug right now unless $session_start and $session_end are always more than a day apart, because sometime the event will happen in between the 24 hour periods you are looping by.