Allow layout-altering automigrations of event tables#5269
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This commit adds special handling in automigrations to accept a broad set of schema- and layout-altering automigrations on event tables, including changes that we'd reject for non-event tables like removing or reordering columns, or layout-incompatibly changing the types of existing columns. This is due to a change we want to make to the ControlDB schema, where we have a product type which is used both as a table type, and as the column type of an event table, and we want to add an element to that product type. I've added a simple smoketest of the new behavior, `automigrate_reschema_event_table_arbitrarily`. Note that I have not tested commitlog replay of a database which has undergone one of these migrations, which has been a common place that bugs have appeared in similar changes in the past. I have done a pretty lazy job with the migration plan formatter for the new step, just printing the name of the event table which is changing, not any information about the specific changes or the columns. This is in an effort to save time, as we'd like to release the ControlDB change blocked by this.
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Can we add a commitlog replay test for this? In particular replay from snapshot?
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I am not sure how we would do that. To my knowledge, we don't currently have any tests of commitlog replay, or any infrastructure for testing it. |
Tested manually by doing the same automigrations as in the smoketest, then restarting the database and calling a procedure in the migrated database to force replay.
…klabs/SpacetimeDB into phoebe/automigrate-event-tables
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I have not added an automated test of replay, but I tested it manually, and it worked after my latest commit. |
joshua-spacetime
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Jun 11, 2026
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Description of Changes
This commit adds special handling in automigrations to accept a broad set of schema- and layout-altering automigrations on event tables, including changes that we'd reject for non-event tables like removing or reordering columns, or layout-incompatibly changing the types of existing columns.
This is due to a change we want to make to the ControlDB schema, where we have a product type which is used both as a table type, and as the column type of an event table, and we want to add an element to that product type.
I've added a simple smoketest of the new behavior,
automigrate_reschema_event_table_arbitrarily. Note that I have not tested commitlog replay of a database which has undergone one of these migrations, which has been a common place that bugs have appeared in similar changes in the past.I have done a pretty lazy job with the migration plan formatter for the new step, just printing the name of the event table which is changing, not any information about the specific changes or the columns. This is in an effort to save time, as we'd like to release the ControlDB change blocked by this.
API and ABI breaking changes
N/a
Expected complexity level and risk
3 at least: new categories of automigrations have a high risk to introduce commitlog replay bugs, and it's also possible I have misunderstood or mis-remembered some of the safety invariants of the
tablecrate.Testing
return_valuein the migrated module to force commitlog replay.