Why does codeigniter database cache regenerates file? - sql-server

Question

I've used Codeigniter Database Cache for a while and it works quite good, but now I have a weird problem with a specific query. The steps are as follow:
My cache directory is empty.
I open the URL /myproject/mycontroller/myaction/
The file is cached in mycontroller-myaction directory (I open the file with my notepad to be sure that it contains the correct data.
I open again the /myproject/mycontroller/myaction/ expecting the data to be retrieved from the cache and turns out that the data is retrieved from the database and the file y regenerated. I don't know why but the point is that the file generated is being useless.
If is important to you I give you the next info:
The query is a stored procedure.
I have other queries that are working perfectly.
I'd really appreciate your help, if you need specific data just let me know.
Thanks.
Using xdebug I found out that in the DB_driver.php file in the query function, there is a condition in the line 277 that says as follow:
// Is query caching enabled? If the query is a "read type"
// we will load the caching class and return the previously
// cached query if it exists
if ($this->cache_on == TRUE AND (stristr($sql, 'SELECT')))
{
if ($this->_cache_init())
{
$this->load_rdriver();
if (FALSE !== ($cache = $this->CACHE->read($sql)))
{
return $cache;
}
}
}
where the query must be a SELECT, and I am using a stored procedure and my model is:
public function cobertura($param1= NULL) {
$query = $this->db->query("[SP_NAME] ?", array($param1));
}
return $query->result();
}
So as I'm using a stored procedure instead of a SELECT statement, the condition returns FALSE and generates again the cache file.
How could I modify that function in order to detect my stored procedure as a valid statement?
Thank you very much.

Answer 1

Well, the solution for this problem was modify this
if ($this->cache_on == TRUE AND (stristr($sql, 'SELECT')))
by this
if ($this->cache_on == TRUE AND (stristr($sql, 'SELECT') OR strpos($sql, '[')))
This way I tell CI that when my sql statment starts with [ is a SELECT query too.
And when I have an stored procedure that is not a select statement simply disable the cache.
If you have a better solution you can share.

Answer 2

You should not use the query cache in CodeIgniter. It is not safe to use unless you know exactly what you are doing.
Instead I would create a cacheQuery function or something like it to at least give you control over caching for queries. The assumption that any query that returns data or might return data can be cached is very risky.
By replacing CI's attempted automation and doing it manually you will also gain some speed. If you xdebug profile all the guessing CI is doing about your queries add a lot of overhead to the query function.
The solution posted above might also be a bit dodgy because not all stored procedures return data and the square bracket could be anywhere in your queries so that check can get it wrong. It will return false if the first character and return true if the character is anywhere in the query even if it doesn't make up a stored procedure. For example, DELETE FROM table1 WHERE column1="[xxx]".
This kind of thing stristr($sql, 'SELECT') and strpos($sql, '[') are not good. CodeIgniter is simple, tidy, consistent and well organised but the actually quality of PHP code in it is extremely poor. To be fair, part of this is because it maintains compatibility with much older versions of PHP but there are several things that are inexplicably bad. When it comes to this kind of thing the CodeIgniter policy is "If it works 90% or more of the time then it's ok". This is of course not good for large serious enterprise applications.