internal/integration: test mysql auto_increment

Also, fix minor diff issue in AUTO_INCREMENT migration

internal/integration/script_test.go

@@ -154,8 +154,16 @@ func (t *myTest) cmdCmpShow(ts *testscript.TestScript, _ bool, args []string) {
 		if err := t.db.QueryRow(fmt.Sprintf("SHOW CREATE TABLE `%s`.`%s`", schema, name)).Scan(&name, &create); err != nil {
 			return "", err
 		}
-		// Trim the "table_options" if it was not requested explicitly.
-		return create[:strings.LastIndexByte(create, ')')+1], nil
+		i := strings.LastIndexByte(create, ')')
+		create, opts := create[:i+1], strings.Fields(create[i+1:])
+		for _, opt := range opts {
+			switch strings.Split(opt, "=")[0] {
+			// Keep only options that are relevant for the tests.
+			case "AUTO_INCREMENT", "COMMENT":
+				create += " " + opt
+			}
+		}
+		return create, nil
 	})
 }
 

internal/integration/testdata/mysql/autoincrement.txt

@@ -0,0 +1,93 @@
+apply 1.hcl
+cmpshow users 1.sql
+
+# Setup a custom AUTO_INCREMENT initial value.
+apply 2.hcl
+cmpshow users 2.sql
+
+# Increase the AUTO_INCREMENT value.
+apply 3.hcl
+cmpshow users 3.sql
+
+-- 1.hcl --
+schema "$db" {}
+
+table "users" {
+  schema = schema.$db
+  column "id" {
+    null = false
+    type = bigint
+    auto_increment = true
+  }
+  primary_key  {
+    columns = [column.id]
+  }
+}
+
+-- 1.sql --
+CREATE TABLE `users` (
+  `id` bigint(20) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`id`)
+)
+
+-- 8/1.sql --
+CREATE TABLE `users` (
+  `id` bigint NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`id`)
+)
+
+-- 2.hcl --
+schema "$db" {}
+
+table "users" {
+  schema = schema.$db
+  column "id" {
+    null = false
+    type = bigint
+    auto_increment = true
+  }
+  primary_key  {
+    columns = [column.id]
+  }
+  auto_increment = 1000
+}
+
+-- 2.sql --
+CREATE TABLE `users` (
+  `id` bigint(20) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`id`)
+) AUTO_INCREMENT=1000
+
+-- 8/2.sql --
+CREATE TABLE `users` (
+  `id` bigint NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`id`)
+) AUTO_INCREMENT=1000
+
+-- 3.hcl --
+schema "$db" {}
+
+table "users" {
+  schema = schema.$db
+  column "id" {
+    null = false
+    type = bigint
+    auto_increment = true
+  }
+  primary_key  {
+    columns = [column.id]
+  }
+  auto_increment = 2000
+}
+
+-- 3.sql --
+CREATE TABLE `users` (
+  `id` bigint(20) NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`id`)
+) AUTO_INCREMENT=2000
+
+-- 8/3.sql --
+CREATE TABLE `users` (
+  `id` bigint NOT NULL AUTO_INCREMENT,
+  PRIMARY KEY (`id`)
+) AUTO_INCREMENT=2000

sql/mysql/diff.go

@@ -228,10 +228,16 @@ func (*diff) charsetChange(from, top, to []schema.Attr) schema.Change {
 // attribute in case it is not the default.
 func (*diff) autoIncChange(from, to []schema.Attr) schema.Change {
 	var fromA, toA AutoIncrement
-	// The table is empty and AUTO_INCREMENT was not configured. This can happen
-	// because older versions of MySQL (< 8.0) stored the AUTO_INCREMENT counter
-	// in main memory (not persistent), and the value is reset on process restart.
-	if sqlx.Has(from, &fromA) && sqlx.Has(to, &toA) && fromA.V <= 1 && toA.V > 1 {
+	switch fromHas, toHas := sqlx.Has(from, &fromA), sqlx.Has(to, &toA); {
+	// Ignore if the AUTO_INCREMENT attribute was dropped from the desired schema.
+	case fromHas && !toHas:
+	// The AUTO_INCREMENT exists in the desired schema, and may not exists in the inspected one.
+	// This can happen because older versions of MySQL (< 8.0) stored the AUTO_INCREMENT counter
+	// in main memory (not persistent), and the value is reset on process restart for empty tables.
+	case toA.V > 1 && toA.V > fromA.V:
+		// Suggest a diff only if the desired value is greater than the inspected one,
+		// because this attribute cannot be maintained in users schema and used to set
+		// up only the initial value.
 		return &schema.ModifyAttr{
 			From: &fromA,
 			To:   &toA,

sql/mysql/sqlspec.go

@@ -92,11 +92,11 @@ func convertTable(spec *sqlspec.Table, parent *schema.Schema) (*schema.Table, er
 	// MySQL allows setting the initial AUTO_INCREMENT value
 	// on the table definition.
 	if attr, ok := spec.Attr("auto_increment"); ok {
-		b, err := attr.Int64()
+		v, err := attr.Int64()
 		if err != nil {
 			return nil, err
 		}
-		t.AddAttrs(&AutoIncrement{V: b})
+		t.AddAttrs(&AutoIncrement{V: v})
 	}
 	return t, err
 }