PDO::pgsqlCopyFromArray

If your $nullAs is '\\N', then you should use $nullAs as is in concatenation of cells of $rows, but send to pgsqlCopyFromArray() escaped version. Also fifth arg $fields should be a SQL-valid string for the column_names placeholder in COPY statement of PostgreSQL.
I provide my smart wrapper for pgsqlCopyFromArray() which do this automatically.
<?php
/**
 *
 * @param PDO $db
 * @param string $tableName
 * @param string[] $fields List of fields names.
 * @param array[] $records Two-demension array of cells (array of rows).
 * @return boolean
 */
function pgInsertByCopy (PDO $db, $tableName, array $fields, array $records) {
 static $delimiter = "\t", $nullAs = '\\N';
 $rows = [];
 foreach ($records as $record) {
 $record = array_map(
 function ($field) use( $record, $delimiter, $nullAs) {
 $value = array_key_exists($field, $record) ? $record[$field] : null;
 if (is_null($value)) {
 $value = $nullAs;
 } elseif (is_bool($value)) {
 $value = $value ? 't' : 'f';
 }
 $value = str_replace($delimiter, ' ', $value);
 // Convert multiline text to one line.
 $value = addcslashes($value, "0円..37円");
 return $value;
 }, $fields);
 $rows[] = implode($delimiter, $record) . "\n";
 }
 return $db->pgsqlCopyFromArray($tableName, $rows, $delimiter, addslashes($nullAs), implode(',', $fields));
}
?>