public IEnumerable<MigrationStep> Aggregate()
{
Dictionary<string, Aggregation> aggregations = FindLargestApplicableAggregations();
foreach (ApplicableMigration applicableMigration in _applicableMigrations)
{
MigrationStepMetadata migrationStepMetadata;
Aggregation aggregation;
if (aggregations.TryGetValue(applicableMigration.Migration.Metadata.ModuleName, out aggregation))
{
// Note: we issue an aggregated migration step when the last migration is hit to adhere more or less
// to the ordering of the migrations.
if (applicableMigration.Migration.Metadata.Timestamp == aggregation.LastAggregatedMigration.Timestamp)
{
// aggregate migration step
migrationStepMetadata = new MigrationStepMetadata(MigrationDirection.Up, false, aggregation.AggregatedMigrations);
Log.Info("Using {0} to aggregate {1} migration(s) from module '{2}'", aggregation.Migration.Implementation.GetName(), migrationStepMetadata.Migrations.Count(), migrationStepMetadata.ModuleName);
yield return new MigrationStep(aggregation.Migration.Implementation, migrationStepMetadata);
}
if (applicableMigration.Migration.Metadata.Timestamp <= aggregation.Migration.Metadata.Timestamp)
{
continue; // the migration will be included in the aggregate
}
}
// single migration step
migrationStepMetadata = new MigrationStepMetadata(applicableMigration.Direction, applicableMigration.Migration.UseModuleNameAsDefaultSchema, new[] { MetadataFor(applicableMigration) });
yield return new MigrationStep(applicableMigration.Migration.Implementation, migrationStepMetadata);
}
}
/// <summary>
/// Alters the database schema by applying the specified migration. Versioning is unaffected by this operation and any timestamp information on the <paramref name="migration"/> is disregarded.
/// </summary>
public void Alter(IMigration migration)
{
if (migration is IReversibleMigration)
{
Log.Info(LogCategory.General, "Migrations used to modify the database schema directly cannot be reversed.");
}
var migrationMetadata = new MigrationMetadata(0, "Bypass", "This migration is being executed without affecting the versioning.");
var stepMetadata = new MigrationStepMetadata(MigrationDirection.Up, false, new[] { migrationMetadata });
var batch = new MigrationBatch(new[]
{
new MigrationStep(migration, stepMetadata)
}, Enumerable.Empty<IMigrationMetadata>(), new NoVersioning(), Configuration);
batch.Execute();
}