14 lines
554 B
Markdown
14 lines
554 B
Markdown
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### How to write migrations?
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We only write `up` migrations, `down` migrations are not always possible in sqlite or
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too complex/too expensive. For example to remove a column you would have to duplicate
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the table, copy over the data, delete and recreated.
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This can be very expensive for some tables (user_messages for example), so should not be attempted.
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### Notes
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One issue we faced multiple times is that updates to `user_messages` can be very
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expensive, leading to slow upgrade times and interrupted migrations. So avoid
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writes if not necessary.
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