How to debug a delete query? I'm trying to debug an issue with a delete query not happening. I've added logging before the query, after the query and I'm logging the return value of the query. Everything looks right, the only problem is that the rows are still in the database. 

It's a simple query, I can't see anything wrong with it:

$result = db_delete('cloud_files')
  -&gt;condition('uri', $uri)
  -&gt;execute();


I've checked the $uri in every way I possibly can and it's right. I've tried executing the delete query by hand and it works just fine. The table name is correct, the field name is correct, the $uri is correct. I don't know what else to check. 

I've used the Devel module to log the queries and while it logs queries that happen both before and after this query, it doesn't log this query at all. However, I've got error_log() calls before and after the query so I know this code is being run and it reports that it is running successfully.

I've even added code to select the data before deleting it and it works!

$select = db_select('cloud_files', 'cf')
                -&gt;fields('cf')
                -&gt;condition('uri', $uri)
                -&gt;execute();

$entry = $select-&gt;fetchAssoc();

error_log("entry: ".print_r($entry, true));


That works, it prints out the row I'm trying to delete.

dqp() doesn't work for delete queries, so I don't know of any way of getting the truly final sql being executed. 

I've made sure that if I connect using the mysql command line client from the drupal host with the user/password in the drupal config that all of the commands work. 

How do I debug this? What is going wrong?

EDIT: 

Is there any kind of transaction happening during a delete action? Could this behavior be the result of those delete queries happening in a transaction that gets aborted?
With a problem like this, you may need to turn on MySQL query logging.  Once logging is enabled, put a noticeable query right before and after your DELETE query (do you can have something easy to search for), check the logs, and go from there.  Just be sure to disable logging when you are done.  It can kill performance and also fill up the disk pretty quickly.