Prisma no data loss migrations
Hi ,Is it common practice to modified the generated sql migration such as replacing drop statements with alter or update statements?
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Yes, it is a common and recommended practice to modify the generated SQL migration files in Prisma to avoid data loss, especially when dealing with column renames or changes that could potentially lead to data loss.
Prisma Migrate generates SQL migration files based on changes in your Prisma schema, but it doesn't always create the most optimal or data-safe migrations. In cases where the default migration might lead to data loss, it's advisable to edit the migration file before applying it.
Here are some key points to consider:
1. Prisma provides a workflow for customizing migrations:
- Use
prisma migrate dev --create-only to generate a draft migration
- Edit the SQL file
- Apply the modified migration with prisma migrate dev
2. Replacing DROP statements with ALTER or UPDATE statements is a common technique to preserve data, especially when renaming columns or changing table structures.
3. Prisma's documentation explicitly mentions this practice. As stated in Customizing migrations:
"In some scenarios, you need to edit a migration file before you apply it. For example, to change the direction of a 1-1 relation (moving the foreign key from one side to another) without data loss, you need to move data as part of the migration - this SQL is not part of the default migration, and must be written by hand."
4. The documentation provides examples of how to modify migrations, such as renaming a field or changing the direction of a 1-1 relation.
5. It's important to note that while this practice is common and often necessary, it requires careful consideration and testing to ensure data integrity.
Remember, when working with production databases, it's crucial to thoroughly test your migrations in a staging environment before applying them to production. Always backup your data before performing migrations that involve structural changes to your database.Hey @yehtet804 👋
Can you please explain your use case? If you want to customize your migration before appying them, you should use create only flag
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