Meteor, MongoDB, oplog tailing and you

gistfile1.md

Meteor, MongoDB, oplog tailing and you

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Prior art

• Pub sub
• Live data sets
• Poll and diff

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What's wrong with poll and diff?

• More writes, more polls
• Mongo bandwidth
• Large record sets
• Latency

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What is oplog?

• MongoDB replica set
• A capped collection
• A rolling record of all operations that modify data

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What is oplog tailing?

• Follow along and find out about changes immediately
• Let the database tell us when things have changed

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What does an entry look like?

{
    "ts" : Timestamp(1396897233, 1),
    "h" : NumberLong(-8686789604923146223),
    "v" : 2,
    "op" : "i",
    "ns" : "bookstore.users",
    "o" : {
        "password" : "$2a$10$ZK5uFJ8T4Z.TMbvafMIpauYQf0CrGN2DXbJrgVlbFlOgDHnTjWTw6",
        "email" : "test@example.org",
        "name" : "Test User",
        "settings" : {
            "fontSize" : 160,
            "colourScheme" : "standard"
        },
        "books" : [],
        "canAccessKeystone" : false,
        "joinDate" : ISODate("2014-04-07T19:00:33.371Z"),
        "_id" : ObjectId("5342f5d15d28ce2802021770"),
        "__v" : 0
    }
}

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What does it mean?

• Less computation
• Reduced db bandwidth
• More connected clients
• Profit?

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More info

• http://www.manuel-schoebel.com/blog/meteorjs-and-mongodb-replica-set-for-oplog-tailing
• http://www.slideshare.net/yaliceme/glasser-devshop10oplog

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Nice! Great Summary!