encodings.js

var zlib = require('zlib');
var snappy = require('snappy');
var avro = require('node-avro-io');
var toArray = require('stream-to-array');
var schema = {
    "namespace": "org.wikimedia.mediawiki",
    "type": "record",
    "name": "EditEvent",
    "fields" : [
        {"name": "action", "type": "string"},
        {
            "name": "meta",
            "type": "record",
            "fields": [
                {"name": "wiki", "type": "string" },
                {"name": "webHost", "type": "string" },
                {"name": "recvFrom", "type": "string" },
                {"name": "timestamp", "type": "long" },
                {"name": "clientIp", "type": "string" },
                {"name": "seqId", "type": "long" },
                {"name": "uuid", "type": "string" },
                {"name": "userAgent", "type": "string" },
            ]
        },
        {"name": "action_init_type", "type": ["null", "string"]},
        {"name": "action_init_mechanism", "type": ["null","string"]},
        {"name": "action_ready_timing", "type": ["null","long"]},
        {"name": "action_save_intent_timing", "type": ["null","long"]},
        {"name": "action_save_attempt_timing", "type": ["null","long"]},
        {"name": "action_save_success_timing", "type": ["null","long"]},

        {"name": "action_save_failure_type", "type": ["null","string"]},
        {"name": "action_save_failure_message", "type": ["null","string"]},
        {"name": "action_save_failure_timing", "type": ["null","long"]},

        {"name": "action_abort_type", "type": ["null","string"]},
        {"name": "action_abort_mechanism", "type": ["null","string"]},
        {"name": "action_abort_timing", "type": ["null","long"]},

        {"name": "mediawiki_version", "type": ["null","string"]},
        {"name": "page", "type": ["null","string"]},
        {"name": "editing_session_id", "type": ["null","string"]},
        {"name": "user", "type": ["null","string"]},
    ]
};

var record = {
    "action": "saveAttempt",
    "meta": {
        "wiki": "en.wikipedia.org",
        "webHost": "mediawiki-vagrant.dev",
        "recvFrom": "mediawiki-vagrant.dev",
        "timestamp": 1433974402,
        "clientIp": "127.0.0.1",
        "seqId": 1,
        "uuid": "05fcf26",
        "userAgent": "nonya"
    },

    "action_init_type": null,
    "action_init_mechanism": null,
    "action_ready_timing": null,
    "action_save_intent_timing": null,
    "action_save_attempt_timing": null,
    "action_save_success_timing": null,

    "action_save_failure_type": null,
    "action_save_failure_message": null,
    "action_save_failure_timing": null,

    "action_abort_type": null,
    "action_abort_mechanism": null,
    "action_abort_timing": null,

    "mediawiki_version": null,
    "page": null,

    "editing_session_id": null,

    "user": null
};

// Replace null entries with undefined
var jsonRecord = {};
Object.keys(record).forEach(function(key) {
    if (record[key] !== null) {
        jsonRecord[key] = record[key];
    }
});


var writer = new avro.DataFile.Writer(schema, "snappy");
writer.append(record).end();
toArray(writer, function(err, arr) {
    var dataBuffer = Buffer.concat(arr);
    console.log('avro+snappy', dataBuffer.length);
});

var json = JSON.stringify(jsonRecord);
console.log('json', new Buffer(json).length);

var buf = snappy.compressSync(json);
console.log('json+snappy', buf.length);

buf = zlib.deflate(json, function(err, res) {
    console.log('json+deflate', res.length);
});

// Output
// json 221
// json+snappy 198
// json+deflate 160
// avro+snappy 1504 (1327 schema, ~160 data)