aweisberg commented on code in PR #4508:
URL: https://github.com/apache/cassandra/pull/4508#discussion_r2611475463
##########
src/java/org/apache/cassandra/tcm/transformations/AlterSchema.java:
##########
@@ -332,6 +337,64 @@ public static Transformer
maybeUpdateConsensusMigrationState(ConsensusMigrationS
return next;
}
+ /**
+ * Auto-start mutation tracking migration when keyspace replication type
changes.
+ * Detects transitions between tracked and untracked replication and
initializes
+ * migration state accordingly.
+ * Also handles removing dropped tables and keyspaces from migration state.
+ */
+ public static Transformer maybeUpdateMutationTrackingMigrationState(Epoch
nextEpoch,
+
MutationTrackingMigrationState prev,
+
Transformer next,
+
ImmutableList<KeyspaceDiff> altered,
+
Keyspaces dropped)
+ {
+ MutationTrackingMigrationState migrationState = prev;
+
+ // Handle dropped keyspaces - remove their migration state entirely
+ if (!dropped.isEmpty())
+ {
+ Set<String> droppedKeyspaceNames = dropped.stream()
+ .map(ks -> ks.name)
+ .collect(Collectors.toSet());
+ migrationState = migrationState.dropKeyspaces(nextEpoch,
droppedKeyspaceNames);
+ }
+
+ // Handle dropped tables from altered keyspaces
+ Set<TableId> droppedTableIds = altered.stream()
+ .flatMap(diff ->
diff.tables.dropped.stream().map(TableMetadata::id))
+ .collect(Collectors.toSet());
+
+ if (!droppedTableIds.isEmpty())
+ migrationState = migrationState.dropTables(droppedTableIds,
nextEpoch);
+
+ // Handle keyspace replication type changes (new migrations or
reversals)
+ for (KeyspaceDiff diff : altered)
+ {
+ ReplicationType beforeType = diff.before.params.replicationType;
+ ReplicationType afterType = diff.after.params.replicationType;
+
+ // Check if replication type changed
+ if (beforeType != afterType)
+ {
+ // Auto-start migration for this keyspace
+ logger.info("Auto-starting mutation tracking migration for
keyspace {} (replication_type={})",
+ diff.after.name, afterType);
+
+ Collection<TableId> tableIds = diff.after.tables.stream()
+ .map(table -> table.id)
+ .collect(Collectors.toList());
+
+ migrationState =
migrationState.withKeyspaceMigrating(diff.after.name, tableIds, nextEpoch);
Review Comment:
Maybe a comment or a name change to reflect the fact that it does reversal?
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