/**
* Finds all tables that are like the specified base table name.
*
* @param string $table_expression
* An SQL expression, for example "cache_%" (without the quotes).
*
* @return array
* Both the keys and the values are the matching tables.
*/
public function findTables($table_expression)
{
// Load all the tables up front in order to take into account per-table
// prefixes. The actual matching is done at the bottom of the method.
$condition = $this->buildTableNameCondition('%', 'LIKE');
$condition->compile($this->connection, $this);
$individually_prefixed_tables = $this->connection->getUnprefixedTablesMap();
$default_prefix = $this->connection->tablePrefix();
$default_prefix_length = strlen($default_prefix);
$tables = [];
// Normally, we would heartily discourage the use of string
// concatenation for conditionals like this however, we
// couldn't use db_select() here because it would prefix
// information_schema.tables and the query would fail.
// Don't use {} around information_schema.tables table.
$results = $this->connection->query("SELECT table_name FROM information_schema.tables WHERE " . (string) $condition, $condition->arguments());
foreach ($results as $table) {
// Take into account tables that have an individual prefix.
if (isset($individually_prefixed_tables[$table->table_name])) {
$prefix_length = strlen($this->connection->tablePrefix($individually_prefixed_tables[$table->table_name]));
} elseif ($default_prefix && substr($table->table_name, 0, $default_prefix_length) !== $default_prefix) {
// This table name does not start the default prefix, which means that
// it is not managed by Drupal so it should be excluded from the result.
continue;
} else {
$prefix_length = $default_prefix_length;
}
// Remove the prefix from the returned tables.
$unprefixed_table_name = substr($table->table_name, $prefix_length);
// The pattern can match a table which is the same as the prefix. That
// will become an empty string when we remove the prefix, which will
// probably surprise the caller, besides not being a prefixed table. So
// remove it.
if (!empty($unprefixed_table_name)) {
$tables[$unprefixed_table_name] = $unprefixed_table_name;
}
}
// Convert the table expression from its SQL LIKE syntax to a regular
// expression and escape the delimiter that will be used for matching.
$table_expression = str_replace(array('%', '_'), array('.*?', '.'), preg_quote($table_expression, '/'));
$tables = preg_grep('/^' . $table_expression . '$/i', $tables);
return $tables;
}
