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•Created by tort6334 on 8/5/2024 in #help-and-questions

Alternative to solving optimistic concurrency issue without version field

In the following page there is a suggestion how to solve concurrency issue by adding a version field and ask about it in the where clause when updating a model:

const userEmail = '[email protected]'
const movieName = 'Hidden Figures'

// Find the first available seat
// availableSeat.version might be 0
const availableSeat = await client.seat.findFirst({
  where: {
    Movie: {
      name: movieName,
    },
    claimedBy: null,
  },
})

if (!availableSeat) {
  throw new Error(`Oh no! ${movieName} is all booked.`)
}

// Only mark the seat as claimed if the availableSeat.version
// matches the version we're updating. Additionally, increment the
// version when we perform this update so all other clients trying
// to book this same seat will have an outdated version.
const seats = await client.seat.updateMany({
  data: {
    claimedBy: userEmail,
    version: {
      increment: 1,
    },
  },
  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },
})

if (seats.count === 0) {
  throw new Error(`That seat is already booked! Please try again.`)
}

const userEmail = '[email protected]'
const movieName = 'Hidden Figures'

// Find the first available seat
// availableSeat.version might be 0
const availableSeat = await client.seat.findFirst({
  where: {
    Movie: {
      name: movieName,
    },
    claimedBy: null,
  },
})

if (!availableSeat) {
  throw new Error(`Oh no! ${movieName} is all booked.`)
}

// Only mark the seat as claimed if the availableSeat.version
// matches the version we're updating. Additionally, increment the
// version when we perform this update so all other clients trying
// to book this same seat will have an outdated version.
const seats = await client.seat.updateMany({
  data: {
    claimedBy: userEmail,
    version: {
      increment: 1,
    },
  },
  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },
})

if (seats.count === 0) {
  throw new Error(`That seat is already booked! Please try again.`)
}

Reference: https://www.prisma.io/docs/orm/prisma-client/queries/transactions#optimistic-concurrency-control what I want to ask, is if instead of doing:

  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },

  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },

I could have asked if claimedBy is still null, will it do the same trick? so the solution would be like so:

  where: {
    id: availableSeat.id,
    claimedBy: null
  },

  where: {
    id: availableSeat.id,
    claimedBy: null
  },

The only disadvantage compared to version is that if there were many swaps between claimedby and null, i would have not known about it, but that's fine by me I guess?

1 replies

PPrisma

•Created by tort6334 on 7/24/2024 in #help-and-questions

Solve optimistic concurrency issue without adding a `version` field

Question In the following page there is a suggestion how to solve concurrency issue by adding a version field and ask about it in the where clause when updating a model:

const userEmail = '[email protected]'
const movieName = 'Hidden Figures'

// Find the first available seat
// availableSeat.version might be 0
const availableSeat = await client.seat.findFirst({
  where: {
    Movie: {
      name: movieName,
    },
    claimedBy: null,
  },
})

if (!availableSeat) {
  throw new Error(`Oh no! ${movieName} is all booked.`)
}

// Only mark the seat as claimed if the availableSeat.version
// matches the version we're updating. Additionally, increment the
// version when we perform this update so all other clients trying
// to book this same seat will have an outdated version.
const seats = await client.seat.updateMany({
  data: {
    claimedBy: userEmail,
    version: {
      increment: 1,
    },
  },
  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },
})

if (seats.count === 0) {
  throw new Error(`That seat is already booked! Please try again.`)
}

const userEmail = '[email protected]'
const movieName = 'Hidden Figures'

// Find the first available seat
// availableSeat.version might be 0
const availableSeat = await client.seat.findFirst({
  where: {
    Movie: {
      name: movieName,
    },
    claimedBy: null,
  },
})

if (!availableSeat) {
  throw new Error(`Oh no! ${movieName} is all booked.`)
}

// Only mark the seat as claimed if the availableSeat.version
// matches the version we're updating. Additionally, increment the
// version when we perform this update so all other clients trying
// to book this same seat will have an outdated version.
const seats = await client.seat.updateMany({
  data: {
    claimedBy: userEmail,
    version: {
      increment: 1,
    },
  },
  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },
})

if (seats.count === 0) {
  throw new Error(`That seat is already booked! Please try again.`)
}

Reference: https://www.prisma.io/docs/orm/prisma-client/queries/transactions#optimistic-concurrency-control what I want to ask, is if instead of doing:

  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },

  where: {
    id: availableSeat.id,
    version: availableSeat.version, // This version field is the key; only claim seat if in-memory version matches database version, indicating that the field has not been updated
  },

I could have asked if claimedBy is still null, will it do the same trick? so the solution would be like so:

  where: {
    id: availableSeat.id,
    claimedBy: null
  },

  where: {
    id: availableSeat.id,
    claimedBy: null
  },

The only disadvantage compared to version is that if there were many swaps between claimedby and null, i would have not known about it, but that's fine by me I guess?

3 replies

PPrisma

•Created by tort6334 on 6/27/2024 in #help-and-questions

How can I use Prisma with Kubernetes? Any example

I couldn't find a single local development Kubernetes example with Prisma, and like other tools like Skaffold. How can I do that? Prisma is an interesting case because it requires also post processing of migration, deployment and creation of the schemas.

2 replies

PPrisma

•Created by tort6334 on 5/27/2024 in #help-and-questions

Any expected SDL-First generator with CRUD abilities?

Hi guys, I really like Prisma and I want to use it with GraphQL, the thing is, I want to generate automatically all CRUD operations based on my schema, and the only valid option right now is to use TypeGraphQL, and I prefer to use Schema First language, will there be a generator for that?

12 replies

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