CODEWITHSUNDEEP
node.jsmultithreadingcluster-computingcomputer-sciencerethinkdb
tofaelahmed
tofaelahmed

Reputation: 101

Concurrent safe short unique integer id generation in nodeJS

I have a node application where I am using rethinkdb as database. The id rethinkdb generates for each document is not human readable and not suitable for real world reference purpose.

For example, each user I create I want to have a short integer id which I can use to refer that user in real world. The id I get from database is not suitable for that.

What would be a concurrent safe way to generate a short unique integer id ?

Upvotes: 2

Views: 551

Answers (2)

vbranden
vbranden

Reputation: 5986

Building off of @Suvitruf 's answer you can accomplish this in pure reql using the following where "last" is a table that contains the last id. Modifications made here are specifically for parallel updates. Instead of individual id updates for each update, the number block is reserved in 1 insert that is part of the query. Please award any points to his answer.

r([{ foo: 'a' }, { foo: 'b'}])
.do(records => {
    return r.table('lastId').get('last')('current')
  .do(current => {
    return r.table('lastId').get('last').update({ current: current.add(records.count()) })
    .do(() => {
      return r.range(0, records.count()).map(idx => {
        return records.nth(idx).merge(rec => {
            return { id: current.add(idx) }
        })
      })
    })
  })
})
.coerceTo('array')
.do(records => {
    return r.table('ids').insert(records)    
})

Upvotes: 1

Suvitruf - Andrei Apanasik
Suvitruf - Andrei Apanasik

Reputation: 5672

You can create new table, for example, System.

Add to this table just one record:

{
    id: "myLastId",
    current: 0
}

When you want to insert new record to another table, you need to increment this id first and return it:

const getNewId = r.table("System").get("myLastId").update({
                                current: r.row("current").add(1)
                            },
                            {returnChanges: true});

Your new id will be in result.changes[0]["new_val"].current. Now, you can insert new record with this id.

Yes, you have to send additional request each time you want to insert new record, but, at least, this method is 100% atomic and synchronized between all nodes in cluster.

Upvotes: 0

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