Remove transaction from abort

All migrations can be aborted idempotently at the moment and hence we
don't need to use a transaction for atomicity.

src/lib.rs

@@ -151,13 +151,10 @@ impl Reshape {
                 last_migration_index + 1,
                 last_action_index + 1,
             );
-            self.state.save(&mut self.db)?;
 
-            self.abort_migrations(
+            // Abort will only
-                &remaining_migrations,
+            self.abort()?;
-                last_migration_index + 1,
+
-                last_action_index + 1,
-            )?;
             return Err(err);
         }
 
@@ -494,31 +491,19 @@ impl Reshape {
                     continue;
                 }
 
-                // Run each action abort as a separate transaction. We need atomicity
-                // to ensure the abort changes are run only once for each action.
-                let mut transaction = self
-                    .db
-                    .transaction()
-                    .context("failed to start transaction")?;
-
                 let ctx = MigrationContext::new(migration_index, action_index);
                 action
-                    .abort(&ctx, &mut transaction)
+                    .abort(&ctx, &mut self.db)
                     .with_context(|| format!("failed to abort migration {}", migration.name))
                     .with_context(|| format!("failed to abort action: {}", action.describe()))?;
 
-                // Update state with which migrations and actions have been aborted. By running this
+                // Update state with which migrations and actions have been aborted.
-                // in a transaction, we guarantee that an action is only aborted once.
+                // We don't need to run this in a transaction as aborts are idempotent.
-                // We want to use a single transaction for each action to keep the length
-                // of the transaction as short as possible.
                 self.state
                     .aborting(migrations.to_vec(), migration_index, action_index);
                 self.state
-                    .save(&mut transaction)
+                    .save(&mut self.db)
                     .context("failed to save state")?;
-                transaction
-                    .commit()
-                    .context("failed to commit transaction")?;
             }
 
             println!("{}", "done".green());

src/migrations/add_column.rs

@@ -250,17 +250,6 @@ impl Action for AddColumn {
     }
 
     fn abort(&self, ctx: &MigrationContext, db: &mut dyn Conn) -> anyhow::Result<()> {
-        // Remove triggers and procedures
-        let query = format!(
-            "
-            DROP TRIGGER IF EXISTS {trigger_name} ON {table};
-            DROP FUNCTION IF EXISTS {trigger_name};
-            ",
-            table = self.table,
-            trigger_name = self.trigger_name(ctx),
-        );
-        db.run(&query).context("failed to drop up trigger")?;
-
         // Remove column
         let query = format!(
             "
@@ -272,6 +261,17 @@ impl Action for AddColumn {
         );
         db.run(&query).context("failed to drop column")?;
 
+        // Remove triggers and procedures
+        let query = format!(
+            "
+            DROP TRIGGER IF EXISTS {trigger_name} ON {table};
+            DROP FUNCTION IF EXISTS {trigger_name};
+            ",
+            table = self.table,
+            trigger_name = self.trigger_name(ctx),
+        );
+        db.run(&query).context("failed to drop up trigger")?;
+
         Ok(())
     }
 }

src/migrations/alter_column.rs

@@ -311,6 +311,17 @@ impl Action for AlterColumn {
     }
 
     fn abort(&self, ctx: &MigrationContext, db: &mut dyn Conn) -> anyhow::Result<()> {
+        // Drop temporary column
+        let query = format!(
+            "
+			ALTER TABLE {table}
+            DROP COLUMN IF EXISTS {temp_column};
+			",
+            table = self.table,
+            temp_column = self.temporary_column_name(ctx),
+        );
+        db.run(&query).context("failed to drop temporary column")?;
+
         // Remove triggers and procedures
         let query = format!(
             "
@@ -327,17 +338,6 @@ impl Action for AlterColumn {
         db.run(&query)
             .context("failed to drop up and down triggers")?;
 
-        // Drop temporary column
-        let query = format!(
-            "
-			ALTER TABLE {table}
-            DROP COLUMN IF EXISTS {temp_column};
-			",
-            table = self.table,
-            temp_column = self.temporary_column_name(ctx),
-        );
-        db.run(&query).context("failed to drop temporary column")?;
-
         Ok(())
     }
 }