->cache(true)->sum('attribute') in mysql doesn't work.

[BenasPaulikas]

What steps will reproduce the problem?

->cache(true)->sum('attribute') in mysql doesn't work.
->cache(true)->one() - works

What is the expected result?

doing 100x ->cache(true)->sum('attribute') would do sql query only 1 time

What do you get instead?

sql query is executed 100x times

Additional info

Q	A
Yii version	2.0.?
PHP version	7
Operating system	Linux

[samdark]

Is that MySQL specific? Does it depend on how cache is configured?

[alex-code]

Which version of Yii are you using?
If it's older than 2.0.14 this could be why.

[BenasPaulikas]

Updated to 2.0.20 looks liek now it works except:

->cache(true)->sum('HOUR(TIMEDIFF(created, completed))')

This is not being cached

[alex-code]

How do you know that it's not caching?
I tested a simple loop with a sum query and it's cached.

[BenasPaulikas]

      for($i = 0; $i < 10; $i++) {
            Request::find()->where(['garage_id' => 153])->cache(true)->sum('HOUR(TIMEDIFF(created, completed))');
        }

[BenasPaulikas]

If I remove ->where(['garage_id' => 153]) then it works .. Is this expected ?

[alex-code]

Do you have a cache configured?

[Arkeins]

Hi !

Even if this issue is old, i face the same problem, so i'll put what i found here, in case that can help someone :)

I believe the sum() result is not cached when there are not results (the query return null).

In that case, queryScalar() (which is used internally by sum()) return false.

When checking the cache, false will then be returned, which also means that there is no valid entry in cache for this query, leading to a new execution.

[bizley]

Could you prepare new issue with that?

[Arkeins]

After some more digging I was kinda right.

The query returns null, which is cached.

The part that fails seems to be this one:

                if (is_array($result) && isset($result[0])) {
                    Yii::debug('Query result served from cache', 'yii\db\Command::query');
                    return $result[0];
                }

(in db/Command.php line 1157)

isset seems to return false if the value is null.

Changing to

                if (is_array($result) && array_key_exists(0, $result)) {
                    Yii::debug('Query result served from cache', 'yii\db\Command::query');
                    return $result[0];
                }

fix the issue for me (I have no clue if it breaks anything).

Should i still create a new issue?