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Story #4871
closed
When changing unit_key_fields, the relevant DB units may need to be prepared during migration BEFORE indexes are applied
Start date:
Due date:
% Done:
100%
Estimated time:
Platform Release:
2.20.0
Groomed:
Yes
Sprint Candidate:
Yes
Tags:
Pulp 2
Sprint:
Sprint 53
Quarter:
Description
pulp-manage-db currently creates indexes before migrations are run.
In most cases this is desirable behaviour since it ensures Mongo will enforce uniqueness constraints (see https://pulp.plan.io/issues/4055).
However, when dropping a field from the unit_key_fields of a DB model, this means that the new key is applied (as an index) BEFORE the migration has had a chance to prepare the existing units for the new key.
This can easily turn previously unique units into duplicates, thus breaking any attempt to migrate them.
This makes it essentially impossible to change a unit key in this way.
Actions
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Add an optional pre index part for DB migrations
This is needed to provide a way to prepare the data base for an index change BEFORE that index is applied. The new mechanism is subject to certain risks and limitations. It should only be used where absolutely necessary.
ref #4055, #4138 https://pulp.plan.io/issues/4055 https://pulp.plan.io/issues/4138
closes #4871 https://pulp.plan.io/issues/4871