Remove redundant parameter from previous_migration function (#914)

Remove the `includeInferred` parameter from the `previous_migration` SQL
function as it was set to `true` at all call sites.

Part of #872

Author: andrew-farries

pkg/roll/execute.go

@@ -269,8 +269,8 @@ func (m *Roll) Rollback(ctx context.Context) error {
 		m.logger.LogSchemaDeletion(migration.Name, versionSchema)
 	}
 
-	// get the name of the previous version of the schema
-	previousMigration, err := m.state.PreviousMigration(ctx, m.schema, true)
+	// get the name of the previous migration
+	previousMigration, err := m.state.PreviousMigration(ctx, m.schema)
 	if err != nil {
 		return fmt.Errorf("unable to get name of previous version: %w", err)
 	}

pkg/state/init.sql

@@ -173,9 +173,7 @@ LANGUAGE SQL
 STABLE;
 
 -- Get the name of the previous migration, or NULL if there is none.
--- This ignores previous versions for which no version schema exists, such as
--- versions corresponding to inferred migrations.
-CREATE OR REPLACE FUNCTION placeholder.previous_migration (schemaname name, includeInferred boolean)
+CREATE OR REPLACE FUNCTION placeholder.previous_migration (schemaname name)
     RETURNS text
     AS $$
     WITH RECURSIVE ancestors AS (
@@ -208,15 +206,6 @@ CREATE OR REPLACE FUNCTION placeholder.previous_migration (schemaname name, incl
             ancestors a
     WHERE
         a.depth > 0
-        AND (includeInferred
-            OR (a.migration_type = 'pgroll'
-                AND EXISTS (
-                    SELECT
-                        s.schema_name
-                    FROM
-                        information_schema.schemata s
-                    WHERE
-                        s.schema_name = schemaname || '_' || a.name)))
     ORDER BY
         a.depth ASC
     LIMIT 1;

pkg/state/state.go

@@ -266,11 +266,11 @@ func (s *State) PreviousVersion(ctx context.Context, schema string, includeInfer
 }
 
 // PreviousMigration returns the name of the previous migration
-func (s *State) PreviousMigration(ctx context.Context, schema string, includeInferred bool) (*string, error) {
+func (s *State) PreviousMigration(ctx context.Context, schema string) (*string, error) {
 	var parent *string
 	err := s.pgConn.QueryRowContext(ctx,
-		fmt.Sprintf("SELECT %s.previous_migration($1, $2)", pq.QuoteIdentifier(s.schema)),
-		schema, includeInferred).Scan(&parent)
+		fmt.Sprintf("SELECT %s.previous_migration($1)", pq.QuoteIdentifier(s.schema)),
+		schema).Scan(&parent)
 	if err != nil {
 		return nil, err
 	}