The cubrid_lob_size function returns the size of BLOB/CLOB data. The maximum size of BLOB/CLOB data is the same as the maximum file size in an external storage. LOB type size of CUBRID PHP is 64-bit integer but 64-bit integer cannot be returned in PHP. Therefore, string is returned instead.
bool cubrid_lob_size(resource $lob_identifier )
<?php
$lobs = cubrid_lob_get($con, "SELECT doc_content FROM doc WHERE doc_id=5");
echo "Doc size:".cubrid_lob_size($lobs[0]);
cubrid_lob_export($conn, $lobs[0], "doc_5.txt");
cubrid_lob_close($lobs);
?>