Writer Sync Avro C

[Marius <m....@googlemail.com>]

He Guys,

i am currently using Avro C to serialize some data to the file. The 
program itsself is written in Python so i use Python Extensions and this 
implementation https://github.com/Byhiras/pyavroc. The problem is i need 
the file to be seekable. E.g. each datum i want to serialize has an ID , 
and i want to seek to that position and be able to read exactly that 
datum without having to parse across the whole file.
  In io.h of the Avro C are methods called avro_file_writer_sync and 
avro_writer_tell. I thought these might be used to write the data to the 
file after each datum and then return the current offset of the file so 
i know where each datums starts.
  But when i implemented this the function returned a constant value. 
Are these the right methods for doing this and my code is wrong or do i 
use the wrong methods?

Greetings

Marius