`migrate dev --create-only` with empty schema but existing database schema detects drift and warns about deleting all data

Bug description

• No modesl in schema.prisma
• 1 table in database schema
• Running migrate dev --create-only gives following output:

PS C:\Users\piotr\Documents\serverless-prisma\demo> npx prisma migrate dev --create-only
Environment variables loaded from .env
Prisma schema loaded from prisma\schema.prisma
Datasource "db": PostgreSQL database "tests", schema "public" at "localhost:5432"

√ Drift detected: Your database schema is not in sync with your migration history.

We need to reset the PostgreSQL database "tests" at "localhost:5432".
Do you want to continue? All data will be lost. ... yes

√ Name of migration ... init
Prisma Migrate created the following migration without applying it 20210414181550_init

You can now edit it and apply it by running prisma migrate dev.

--create-only needing to reset my database, and supposedly even doing that, was unexpected.

Expected behavior

No changes on data or warnings that indicate that when using --create-only.

Prisma information

PS C:\Users\piotr\Documents\serverless-prisma\demo> npx prisma -v
Environment variables loaded from .env
prisma               : 2.21.1
@prisma/client       : 2.21.1
Current platform     : windows
Query Engine         : query-engine e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules\@prisma\engines\query-engine-windows.exe)
Migration Engine     : migration-engine-cli e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules\@prisma\engines\migration-engine-windows.exe)
Introspection Engine : introspection-core e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules\@prisma\engines\introspection-engine-windows.exe)
Format Binary        : prisma-fmt e421996c87d5f3c8f7eeadd502d4ad402c89464d (at node_modules\@prisma\engines\prisma-fmt-windows.exe)
Default Engines Hash : e421996c87d5f3c8f7eeadd502d4ad402c89464d
Studio               : 0.371.0

[richin13]

I tried using --create-only and ignoring the reset warning hoping it would not reset my DB until I applied the migration on a separate step but instead it wiped my data. Here are the reproduction steps:

1. I had an existing local development database, generated by a different framework.
2. I ran prisma db pull to generate a schema.prisma file based on the existing db structure. At this point I have no prisma/migrations/ folder.
3. I ran prisma migrate dev --name initial-migration --create-only to generate an initial migration based on the existing schema of my DB. I received the warning that, even though I specified --create-only my DB still needs to be reset. I approved it and I ended up with a brand new migration file (just as expected by using prisma migrate) but with an empty local development database (to me, unexpected given that I specified --create-only)

Drift detected: Your database schema is not in sync with your migration history.

I received the above error upon running prisma migrate dev --name initial-migration --create-only

[NaveenKJammula]

can confirm the issue still exists. prisma migrate dev --create-only should never reset the data. unless we specifically apply it manually.