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Support "ADD COLUMN IF NOT EXISTS"

See original GitHub issue

Issue Creation Checklist

I understand that my issue will be automatically closed if I don’t fill in the requested information
I have read the contribution guidelines

Feature Description

Describe the feature you’d like to see implemented

When creating a new column with addColumn, I’d like to be able to provide an option for the method to not crash if the column already exists. For example:

await queryInterface.addColumn('MyTable', 'new_col', {
  type: Sequelize.INTEGER,
}, {
  mustExist: false, // Prevents crashing if the column already exists
);

Using Postgres as a reference, the generated SQL would look like this:

ALTER TABLE "MyTable" ADD COLUMN IF NOT EXISTS "new_col";

Describe why you would like this feature to be added to Sequelize

Because migrations don’t happen in transactions, you can end up with a partially-executed migration that needs to be re-triggered. Adding support for this option would make it easier to have resiliant migrations that can be executed multiple times.

Is this feature dialect-specific?

No. This feature is relevant to Sequelize as a whole.
Yes. This feature only applies to the following dialect(s):
- Postgres: ADD COLUMN IF NOT EXISTS is officially supported
- MySQL: Not officially supported. Possible workarounds?
- MSSQL: Not officially supported. Possible workarounds?
- SQLite: Not officially supported. Possible workarounds?

Would you be willing to resolve this issue by submitting a Pull Request?

Yes, I have the time and I know how to start.
Yes, I have the time but I will need guidance.
No, I don’t have the time, but my company or I are supporting Sequelize through donations on OpenCollective.
No, I don’t have the time, and I understand that I will need to wait until someone from the community or maintainers is interested in implementing my feature.

Context

Indicate your interest in the addition of this feature by adding the 👍 reaction. Comments such as “+1” will be removed.

Issue Analytics

State:
Created a year ago
Reactions:2
Comments:6 (5 by maintainers)

Top GitHub Comments

2reactions

ephyscommented, Oct 10, 2022

Feel free 😃 My only note is, because of the support table (does any other dialect than postgres support this?) I think this shouldn’t be the default & add a ifNotExists option. If the dialect doesn’t support IF NOT EXISTS, it should throw instead of silently ignoring the option

2reactions

ephyscommented, Sep 17, 2022

Sounds like a nice addition, we welcome it. I think dialects that don’t support it and don’t have a clean workaround could query whether the column exists first

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