SQL connection error from PHP after many operations - php

Question

I'm currently looping to create a MBTiles map, and add information to my database each time.
Here's how I configured my connection and execute actions during the loop:
if ($pdo_mbtiles == null) {
echo "Opening new database connection".PHP_EOL;
$pdo_mbtiles = new PDO('sqlite:'.$filename,
'',
'',
array(
PDO::ATTR_PERSISTENT => true
)
);
$pdo_mbtiles->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$pdo_mbtiles->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
$q = $pdo_mbtiles->prepare("INSERT INTO tiles (zoom_level, tile_column, tile_row,tile_data) VALUES (:zoom_level, :tile_column, :tile_rowTMS, :tile_data)");
$q->bindParam(':zoom_level', $zoom_level);
$q->bindParam(':tile_column', $tile_column);
$q->bindParam(':tile_rowTMS', $tile_rowTMS);
$q->bindParam(':tile_data', $tile_data, PDO::PARAM_LOB);
$q->execute();
After 1018 times looping (this number doesn't change no matter how many times I try), I get this error message:
SQLSTATE[HY000]: General error: 14 unable to open database file
I checked the solution written here:
How to prevent SQLITE SQLSTATE[HY000] [14]?
but the echoed message only appears at the first time of the loop, so I assume the PDO connection isn't closed.
I didn't find other documentation relevant to this error code.
What could possibly go wrong here?
I tried to move the prepare and bind commands in a condition as follows. The exception isn't raised, but only the first tile is saved (or every tile is saved on top of the first one, not sure):
if ($pdo_mbtiles == null) {
echo "Opening new database connection".PHP_EOL;
$pdo_mbtiles = new PDO('sqlite:'.$filename,
'',
'',
array(
PDO::ATTR_PERSISTENT => true
)
);
$pdo_mbtiles->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
$pdo_mbtiles->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
if ($q == null) {
$q = $pdo_mbtiles->prepare("INSERT INTO tiles (zoom_level, tile_column, tile_row,tile_data) VALUES (:zoom_level, :tile_column, :tile_rowTMS, :tile_data)");
$q->bindParam(':zoom_level', $zoom_level);
$q->bindParam(':tile_column', $tile_column);
$q->bindParam(':tile_rowTMS', $tile_rowTMS);
$q->bindParam(':tile_data', $tile_data, PDO::PARAM_LOB);
}
$q->execute();
Here are the files during the generation:
And here after the exception is raised:
Also, when the exception is raised, I do a var_dump of my $pdo_mbtiles, and here's the result (exactly the same as when I do it with a success):
object(PDO)#116 (0) {
}
Edit: Still trying to solve this problem, I simplified the code to create the MBTiles file. No success yet, but here's a sample if anyone want's to reproduce the issue. You can download it from https://www.dropbox.com/s/33vqamc9tn4c3ux/sample_PHP_MBTiles_generation_bug.zip?dl=0

Answer 1

I suggest you to reuse the connection if it is open.
Create a property: private $pdo;
And check if it's null before creating a new object:
function opendatabase(){
try{
if($this->pdo==null){
$this->pdo =new PDO("sqlite:database/database.db","","",array(
PDO::ATTR_PERSISTENT => true
));
}
return $this->pdo;
}catch(PDOException $e){
logerror($e->getMessage(), "opendatabase");
print "Error in openhrsedb ".$e->getMessage();
}
}

Answer 2

The error message was misleading. After many hours of debugging, I found that it was completely unrelated to my database connection.
It's juste that I used fopen() to get tiles data, and didn't fclose() after registration, thus reaching the limit of 1024.
1024 is because I used six require or require_once statements, so 1018 tile requests + 6 require = 1024 opened connections.