Re: Inefficient escape codes.

I guess, You should check, if a blob field and large object access is suitable for you - no escaping etc, just raw binary large objects.

AFAIK, PQExecParams is not the right solution for You. Refer the "Large object" section:

"28.3.5. Writing Data to a Large Object
The function
int lo_write(PGconn *conn, int fd, const char *buf, size_t len);writes len bytes from buf to large object descriptor fd. The fd argument must have been returned by a previous lo_open. The number of bytes actually written is returned. In the event of an error, the return value is negative."