How to solve my sluggish code (using PHP - PDO ) - php

Question

I am using PHP PDO,
this the code :
for ($i = 0; $i < 1000; $i++) {
//select room and insert to chart
$thisDay=date ("Y-m-d");
$query = $db->prepare("SELECT room FROM d_room WHERE activ=1 ORDER BY room");
$query->execute();
for($a = 1; $result = $query->fetch(); $a++) {
$query2 = $db->prepare("INSERT INTO d_chart (date,room,status) VALUES (? + INTERVAL ? DAY,?,0)");
$query2->execute(array($thisDay,$i,$result['room']));
}
}
this code run too slow, How to make better code and fast, < 2 second.

Answer 1

I don't know why you are trying to do this. However,I suggest you not to store this fuzzy data in your database because there are other ways for doing such tasks if time and space constraint is the issue. As you said <2 seconds then storing that big result will not take less than 30seconds even on the local machine.
So what you can do is just store single result in database as follows:
$thisDay=date ("Y-m-d");
$query = $db->prepare("SELECT room FROM d_room WHERE activ=1 ORDER BY room");
$query->execute();
$result = $query->fetchAll(PDO::FETCH_ASSOC); // storing result here would reduce some time to fetch the data inside loop because your script would not require to get the data again and again from server.
$query = $db->prepare("INSERT INTO d_chart (date,room,status) VALUES (? + INTERVAL ? DAY,?,0)");
for($i=0; $i<sizeof($result);$i++)
{
$query->execute(array($thisDay,$i,$result[$i]['room']));
}
and if you want to retrieve the data for next 1000 days then just fetch the single day data from the database and show the result using some mathematical calculations for next 1000 days at the client side, which would be much faster than anything.
However, you should explain what is your aim behind doing such huge task so that you can get better answers.

Answer 2

You should be able to make this significantly simpler by using an INSERT...SELECT query (assuming MySQL)
// Make sure you see any errors that might occur
ini_set('display_errors', 'On');
error_reporting(E_ALL);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$thisDay = date('Y-m-d');
$stmt = $db->prepare('INSERT INTO d_chart (date, room, status)
SELECT (:thisDay + INTERVAL :days DAY), room, 0
FROM d_room WHERE activ = 1'); // there's no need to order these results
$stmt->bindParam(':thisDay', $thisDay);
$stmt->bindParam(':days', $i, PDO::PARAM_INT);
for ($i = 0; $i < 1000; $i++) {
$stmt->execute();
}
If d_room.activ has an index, this would be even faster.

Answer 3

Don't run the exact same query 1000 times!
Check your indexing to speed up the query.
Prepare the query, then execute it in the loop. This is what preparing is for.
Use PDO::beginTransaction and PDO::commit before and after the loop, respectively. Index updates can be expensive and it's faster to do them all at once.
That should at least make it as fast as possible.
$thisDay = date ("Y-m-d"); // Take this outside the loop
$query = $db->prepare("SELECT room FROM d_room WHERE activ=1 ORDER BY room");
$query2 = $db->prepare("INSERT INTO d_chart (date,room,status) VALUES (? + INTERVAL ? DAY,?,0)"); // Prepare this once
$query->execute(); // Just run this once
$rowset = $query->fetchAll (); // Put into an array to re-loop without querying again
$db->beginTransaction (); // Will update indices in bulk - faster
for ($i = 0; $i < 1000; $i++)
{
//select room and insert to chart
foreach ($rowset as $result)
$query2->execute(array($thisDay,$i,$result['room']));
}
$db->commit (); // Apply changes
As you can see, the loop is now much, much tighter - always the first place to look to speed up code.

Answer 4

I am not seeing any reason to run this query thousands time inside the loop. Because it is executing the same query. Put the query outside the loop.
<?php
//select room and insert to chart
$thisDay = date("Y-m-d");
$query = $db->prepare("SELECT room FROM d_room WHERE activ=1 ORDER BY room");
$query->execute();
$query2 = $db->prepare("INSERT INTO d_chart (date,room,status) VALUES (? + INTERVAL ? DAY,?,0)");
$result = $query->fetch();
for ($i = 0; $i < 1000; $i++) {
$query2->execute(array($thisDay, $i, $result['room']));
}