What is faster way to retrieve column constraints in tables - mysql

Question

In order to validate the integrity of data entered into forms by users, one test I must perform is to ensure that the data does not exceed the length of the table column that will hold it. Rather than hard-coding in the maximum length values for the various columns in my tables, I thought it would be more efficient to write a routine that would gather all the relevant constraint information from my tables (here, just the data_type and character_maximum_length) and put it into an associative array in which I could simply retrieve the values with easily writable and readable:
$table_info_array[$table_name][$column_name]['character_maximum_length'];
I found a solution, and it works rapidly on my localhost, but the construction of the $table_info_array is unacceptably slow on my live server. Here is what I coded:
/* Skipped here: set up your PDO $connection first, then: */
// Define your database:
$database_name = "my_database";
$sql = "SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = '" . $database_name ."'";
$stmt = $connection->prepare($sql);
$result = $stmt->execute();
$counter = -1;
$table_array = array();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
foreach ($row as &$value) {
$counter++;
$table_array[$value] = $counter;
}
}
$table_info_array = array();
foreach ($table_array as $table_name => $table_value) {
// Here I'm selecting the data_type and character_maximum_length by column_name, but other information could easily be collected:
$sql = "SELECT column_name, data_type, character_maximum_length FROM information_schema.columns WHERE table_name = '" . $table_name . "'";
$stmt = $connection->prepare($sql);
$result = $stmt->execute();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
$table_info_array[$table_name][$row['column_name']]['data_type'] = $row['data_type'];
$table_info_array[$table_name][$row['column_name']]['character_maximum_length'] = $row['character_maximum_length'];
}
}
This will show everything; notice how concise the results are:
print_r($table_info_array);
The syntax for retrieving table column constraints is therefore:
$table_info_array[$table_name][$column_name]['data_type'];
$table_info_array[$table_name][$column_name]['character_maximum_length'];
For example, now I can retrieve the maximum character length on the 'title' column in my 'artwork' table, like this:
$table_info_array['artwork']['title']['character_maximum_length'];
The construction of the $table_info_array works at lightning speed on my localhost, but on my live server it is unreasonably slow. Is there a faster way to do this?