Google Cloud Query

/**
 * My full data. It's purely made up for an example.
 */
[
    {
        "userId": 10,
        "timestamp": 1000
    },
    {
        "userId": 10,
        "timestamp": 500
    },
    {
        "userId": 5,
        "timestamp": 10
    },
    {
        "userId": 5,
        "timestamp": 1500
    },
    {
        "userId": 5,
        "timestamp": 50
    }
]

/**
 * What I want to recieve
 *
 * Notice the userId is unique and only the largest timestamp is retrieved
 */
[
    {
        "userId": 10,
        "timestamp": 1000
    },
    // {
    //  "userId": 10,
    //  "timestamp": 500
    // },
    // {
    //  "userId": 5,
    //  "timestamp": 10
    // },
    {
        "userId": 5,
        "timestamp": 1500
    },
    // {
    //  "userId": 5,
    //  "timestamp": 50
    // }
]

/**
 * What I actually receive with my query shown in the stackoverflow question
 */
[
    {
        "userId": 10,
        "timestamp": 1000
    },
    {
        "userId": 10,
        "timestamp": 500
    },
    // {
    //  "userId": 5,
    //  "timestamp": 10
    // },
    // {
    //  "userId": 5,
    //  "timestamp": 1500
    // },
    // {
    //  "userId": 5,
    //  "timestamp": 50
    // }
]