CODEWITHSUNDEEP
php
Xhynk
Xhynk

Reputation: 13890

Is there a big difference in performance (PHP loops)

So, let's say I've got a queryable database with 100 data objects in it. I want to show 3 random ones.

I don't have any working code since this is an idea I just had.

Method 1:

so essentially Query for IDs (1, 15, 67) then print each one.

OR

Method 2:

essentially Query ALL posts if (ID = 1, 15, 67) then print each one and if ($counter = 3){ break; }

Method 2 sounds like it would give me a nasty large object. While Method 1 sounds like it would be a more expensive DB query. I think Method 1 would be better, but I'm not sure

Upvotes: 0

Views: 80

Answers (3)

Jeroen De Dauw
Jeroen De Dauw

Reputation: 10918

If your ID column is indexed, which it probably should be, then doing a select with 

WHERE id IN (1, 15, 67)

is very cheap. And it will scale even if you have many more rows in your table. Solution 2 will not scale as it selects the whole table and loads it into memory.

Upvotes: 3

ppetrov
ppetrov

Reputation: 3105

I'm sure method 1 is better:

in method 1 the db engine will iterate through all your posts to find the ones you need, then will send only the 3 ones it selected. in method 2, the db engine will also iterate through all your posts, and then will send a larger object (with all your posts), which will for sure take more time.

hope this was helpfull ;)

Upvotes: 3

SeanCannon
SeanCannon

Reputation: 78006

Method 1 obviously. It wouldn't be a more expensive DB query if you have indexes set up appropriately.

If you are truly curious, you can find your own answer: 

<?
$start = microtime();
doMethodOne();
$end = microtime();

echo 'Method 1 took ' . $end - $start . ' ms<br />';

$start = microtime();
doMethodTwo();
$end = microtime();

echo 'Method 2 took ' . $end - $start . ' ms';

Upvotes: 1

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