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Fast Avro for Python
Python Shell Makefile
Latest commit 152a5d7 @tebeka is 3.5 there yet?


The current Python avro package is packed with features but dog slow.

On a test case of about 10K records, it takes about 14sec to iterate over all of them. In comparison the JAVA avro SDK does it in about 1.9sec.

fastavro is less feature complete than avro, however it's much faster. It iterates over the same 10K records in 2.9sec, and if you use it with PyPy it'll do it in 1.5sec (to be fair, the JAVA benchmark is doing some extra JSON encoding/decoding).

If the optional C extension (generated by Cython) is available, then fastavro will be even faster. For the same 10K records it'll run in about 1.7sec.

fastavro supports the following Python versions:

  • Python 2.6
  • Python 2.7
  • Python 3.4
  • Python 3.5b2
  • pypy
  • pypy3



    import fastavro as avro

    with open('weather.avro', 'rb') as fo:
        reader = avro.reader(fo)
        schema = reader.schema

        for record in reader:


    from fastavro import writer

    schema = {
        'doc': 'A weather reading.',
        'name': 'Weather',
        'namespace': 'test',
        'type': 'record',
        'fields': [
            {'name': 'station', 'type': 'string'},
            {'name': 'time', 'type': 'long'},
            {'name': 'temp', 'type': 'int'},

    records = [
        {u'station': u'011990-99999', u'temp': 0, u'time': 1433269388},
        {u'station': u'011990-99999', u'temp': 22, u'time': 1433270389},
        {u'station': u'011990-99999', u'temp': -11, u'time': 1433273379},
        {u'station': u'012650-99999', u'temp': 111, u'time': 1433275478},

    with open('weather.avro', 'wb') as out:
        writer(out, schema, records)

You can also use the fastavro script from the command line to dump avro files.

fastavro weather.avro

By default fastavro prints one JSON object per line, you can use the --pretty flag to change this.

You can also dump the avro schema

fastavro --schema weather.avro

Here's the full command line help

usage: fastavro [-h] [--schema] [--codecs] [--version] [-p] [file [file ...]]

iter over avro file, emit records as JSON

positional arguments:
  file          file(s) to parse

optional arguments:
  -h, --help    show this help message and exit
  --schema      dump schema instead of records
  --codecs      print supported codecs
  --version     show program's version number and exit
  -p, --pretty  pretty print json


  • No reader schema


As recommended by Cython, the C files output is distributed. This has the advantage that the end user does not need to have Cython installed. However it means that every time you change fastavro/ you need to run make.

For make to succeed you need both python and Python 3 installed, Cython on both of them. For ./ you'll need virtualenv.


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