Re: model->delete error

I'm sorry about your loss, hope you have a backup at least.

My guess is timing and bad luck. A quick look at the source code
suggests that if two deletes of the same Model record overlap during a
small crucial time period, the WHERE condition generated for the
second delete may come out as 1=1.

Here's an example of a sequence of operations that might lead to this
happening:

request 1: enter Model::delete
request 2: enter Model::delete
request 1: Model::delete: check if record exists -> yes
request 2: Model::delete: check if record exists -> yes
request 1: call $db->delete. Record is deleted. Request ends.
request 2: call $db->delete -> enter DboMysqlBase::delete
request 2: DboMysqlBase::delete: obtain default conditions calling
DboSource::defaultConditions
request 2: DboSource::defaultConditions: check if record exists -> NO.
Return null.
request 2: DboSource::conditions: No conditions found, so assume 1=1.
request 2: Delete all records. Request ends.

I haven't tested if this sequence is possible but it seems plausible.

To avoid problems like this the initial SELECT and the DELETEs should
be executed in a transaction.

On Aug 26, 10:20 pm, lloydhome <david.lloydh...@gmail.com> wrote:
> Hi,
>
> I have v1.3.2 running on a production site that has in a controller:
> (effectively, some non-related code removed)
>
> $results = $this->Pipe->find('all', array('conditions'=>$conditions));
> if(sizeof($results) > 1) {
>         $pipes = sizeof($results);
>         for($i = 0; $i < $pipes - 1; $i++) {
>                 $this->Pipe->id = $results[$i]['Pipe']['p_id'];
>                 $this->Pipe->delete();
>                 unset($results[$i]);
>         }
>
> }
>
> so that all but one matching record remains.
>
> Typically, for months now and even within seconds of the error, the
> SQL generated by this code was:
>         DELETE FROM `pipe` WHERE `pipe`.`p_id` = 12345;
>
> until the one time on yesterday it issued:
>         DELETE FROM `pipe` WHERE 1 = 1;
>
> (There went 360000+ records) I see this in the MySQL binlog but cannot
> tell what value for id was set.  It is my understanding that in no
> reasonable case should this cause this SQL to be generated.
>
> Does anyone have an alternate understanding or insight into what went
> wrong?

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