if the attachment on CouchDB is test.pdf is posible change the attachment ext?

[JarbyDev]

Let me explain better, i have php on couch on codeigniter framework, so when i enter the docid pull the attachment from couchDB, but because the file is with the wrong ext i cant view the file online, but the couchDB database is big, some files are store using the wrong file ext. so i want to know if is possible manipulate CouchDB stream to render the correctly on the browser or download.

Thanks for the Advice.