mysql multi_query intermittently fails

Question

function cpanel_populate_database($dbname) 
{ 
     // populate database
     $sql = file_get_contents(dirname(__FILE__) . '/PHP-Point-Of-Sale/database/database.sql');
     $mysqli->multi_query($sql);

     $mysqli->close();
 }

The sql file is a direct export from phpMyAdmin and about 95% of the time runs without issue and all the tables are created and data is inserted. (I am creating a database from scratch)

The other 5% only the first table or sometimes the first 4 tables are created, but none of the other tables are created (there are 30 tables).

I have decided to NOT use multi_query because it seems buggy and see if the the bug occurs by using just mysql_query on each line after semi-colon. Has anyone ran into issue's like this?

Answer 1

I've seen similar issues when using multi_query with queries that can create or alter tables. In particular, I tend to get InnoDB 1005 errors that seem to be related to foreign keys; it's like MySQL doesn't completely finish one statement before moving on to the next, so the foreign keys lack a proper referent.

In one system, I split the problematic statements into their own files. In another, I have indeed run each command separately, splitting on semicolons:

function load_sql_file($basename, $db) {
    // Todo: Trim comments from the end of a line
    log_upgrade("Attempting to run the `$basename` upgrade.");

    $filename = dirname(__FILE__)."/sql/$basename.sql";
    if (!file_exists($filename)) {
        log_upgrade("Upgrade file `$filename` does not exist.");
        return false;
    }

    $file_content = file($filename);
    $query = '';
    foreach ($file_content as $sql_line) {
        $tsl = trim($sql_line);
        if ($sql_line and (substr($tsl, 0, 2) != '--') and (substr($tsl, 0, 1) != '#')) {
            $query .= $sql_line;
            if (substr($tsl, -1) == ';') {
                set_time_limit(300);
                $sql = trim($query, "\0.. ;");
                $result = $db->execute($sql);
                if (!$result) {
                    log_upgrade("Failure in `$basename` upgrade:\n$sql");
                    if ($error = $db->lastError()) {
                        log_upgrade("$error");
                    }

                    return false;
                }

                $query = '';
            }
        }
    }

    $remainder = trim($query);
    if ($remainder) {
        log_upgrade("Trailing text in `$basename` upgrade:\n$remainder");
        if (DEBUG) trigger_error('Trailing text in upgrade script: '.$remainder, E_USER_WARNING);
        return false;
    }

    log_upgrade("`$basename` upgrade successful.");
    return true;
}