protobuf-repeated-type-vs-any

A simple comparison between a protobuf repeated type (array) versus its repeated google.protobuf.Any counterpart. The same type (Person) is used for both.

The idea is to determine the size difference in bytes of binary and JSON formats for the same type stored as an array and as google.protobuf.Any type. Any stores type_url along with the encoded message so naturally it would need more bytes.

Message Definition (person.proto)

syntax = "proto3";

package test;

import "google/protobuf/any.proto";

message Person {
    string first_name = 1;
    string last_name = 2;
    int32 age = 3;
}

message PersonAny {
    repeated google.protobuf.Any persons = 1;
}

message PersonArray {
    repeated Person persons = 1;
}

Test Data

The persons_data array contains the data to populate Person objects:

persons_data = [
    { first_name: "abc", last_name: "def", age: 20 },
    { first_name: "def", last_name: "ghi", age: 21 },
    { first_name: "jkl", last_name: "mno", age: 22 },
    { first_name: "pqr", last_name: "stu", age: 23 },
].freeze

Compile (.proto file)

$ protoc --ruby_out=. ./person.proto

Run Script

$ ./person.rb

Output (bytes):

Any:
- Binary : 196
- JSON   : 373
Array:
- Binary : 56
- JSON   : 197

Comparison (bytes)

Here's the comparison in tabular form:

Type	Binary	JSON
Any	196	373
Array	56	197