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dialect/sql/schema: add prepare option to mysql dialect

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This commit is contained in:
Ariel Mashraki
2020-01-01 19:11:20 +02:00
parent ab732c7654
commit 7fc3689027
4 changed files with 192 additions and 4 deletions
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21
dialect/sql/schema/migrate.go
View File

@@ -179,10 +179,15 @@ func (m *Migrate) create(ctx context.Context, tx dialect.Tx, tables ...*Table) e
// apply applies changes on the given table.
func (m *Migrate) apply(ctx context.Context, tx dialect.Tx, table string, change *changes) error {
// constraints should be dropped before dropping columns, because if a column
// Constraints should be dropped before dropping columns, because if a column
// is a part of multi-column constraints (like, unique index), ALTER TABLE
// might fail if the intermediate state violates the constraints.
if m.dropIndexes {
if pr, ok := m.sqlDialect.(preparer); ok {
if err := pr.prepare(ctx, tx, change, table); err != nil {
return err
}
}
for _, idx := range change.index.drop {
if err := m.dropIndex(ctx, tx, idx, table); err != nil {
return fmt.Errorf("drop index of table %q: %v", table, err)
@@ -232,6 +237,16 @@ type changes struct {
}
}
// dropColumn returns the dropped column by name (if any).
func (c *changes) dropColumn(name string) (*Column, bool) {
for _, col := range c.column.drop {
if col.Name == name {
return col, true
}
}
return nil, false
}
// changeSet returns a changes object to be applied on existing table.
// It fails if one of the changes is invalid.
func (m *Migrate) changeSet(curr, new *Table) (*changes, error) {
@@ -444,3 +459,7 @@ type sqlDialect interface {
alterColumn(*Column) []*sql.ColumnBuilder
addIndex(*Index, string) *sql.IndexBuilder
}
type preparer interface {
prepare(context.Context, dialect.Tx, *changes, string) error
}

74
dialect/sql/schema/mysql.go
View File

@@ -227,6 +227,55 @@ func (d *MySQL) dropIndex(ctx context.Context, tx dialect.Tx, idx *Index, table
return tx.Exec(ctx, query, args, new(sql.Result))
}
// prepare runs preparation work that needs to be done to apply the change-set.
func (d *MySQL) prepare(ctx context.Context, tx dialect.Tx, change *changes, table string) error {
for _, idx := range change.index.drop {
switch n := len(idx.columns); {
case n == 0:
return fmt.Errorf("index %q has no columns", idx.Name)
case n > 1:
continue // not a foreign-key index.
}
var qr sql.Querier
Switch:
switch col, ok := change.dropColumn(idx.columns[0]); {
// If both the index and the column need to be dropped, the foreign-key
// constraint that is associated with them need to be dropped as well.
case ok:
names, err := fkNames(ctx, tx, table, col.Name)
if err != nil {
return err
}
if len(names) == 1 {
qr = sql.AlterTable(table).DropForeignKey(names[0])
}
// If the uniqueness was dropped from a foreign-key column,
// create a "simple index" if no other index exist for it.
case !ok && idx.Unique && len(idx.Columns) > 0:
col := idx.Columns[0]
for _, idx2 := range col.indexes {
if idx2 != idx && len(idx2.columns) == 1 {
break Switch
}
}
names, err := fkNames(ctx, tx, table, col.Name)
if err != nil {
return err
}
if len(names) == 1 {
qr = sql.CreateIndex(names[0]).Table(table).Columns(col.Name)
}
}
if qr != nil {
query, args := qr.Query()
if err := tx.Exec(ctx, query, args, new(sql.Result)); err != nil {
return err
}
}
}
return nil
}
// scanColumn scans the column information from MySQL column description.
func (d *MySQL) scanColumn(c *Column, rows *sql.Rows) error {
var (
@@ -360,3 +409,28 @@ func (d *MySQL) scanIndexes(rows *sql.Rows) (Indexes, error) {
}
return i, nil
}
// fkNames returns the foreign-key names of a column.
func fkNames(ctx context.Context, tx dialect.Tx, table, column string) ([]string, error) {
query, args := sql.Select("CONSTRAINT_NAME").From(sql.Table("INFORMATION_SCHEMA.KEY_COLUMN_USAGE").Unquote()).
Where(sql.
EQ("TABLE_NAME", table).
And().EQ("COLUMN_NAME", column).
// NULL for unique and primary-key constraints.
And().NotNull("POSITION_IN_UNIQUE_CONSTRAINT").
And().EQ("TABLE_SCHEMA", sql.Raw("(SELECT DATABASE())")),
).
Query()
var (
names []string
rows = &sql.Rows{}
)
if err := tx.Query(ctx, query, args, rows); err != nil {
return nil, fmt.Errorf("mysql: reading constraint names %v", err)
}
defer rows.Close()
if err := sql.ScanSlice(rows, &names); err != nil {
return nil, err
}
return names, nil
}

95
dialect/sql/schema/mysql_test.go
View File

@@ -702,6 +702,10 @@ func TestMySQL_Create(t *testing.T) {
WillReturnRows(sqlmock.NewRows([]string{"index_name", "column_name", "non_unique", "seq_in_index"}).
AddRow("PRIMARY", "id", "0", "1").
AddRow("age", "age", "0", "1"))
// check if a foreign-key needs to be dropped.
mock.ExpectQuery(escape("SELECT `CONSTRAINT_NAME` FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE `TABLE_NAME` = ? AND `COLUMN_NAME` = ? AND `POSITION_IN_UNIQUE_CONSTRAINT` IS NOT NULL AND `TABLE_SCHEMA` = (SELECT DATABASE())")).
WithArgs("users", "age").
WillReturnRows(sqlmock.NewRows([]string{"CONSTRAINT_NAME"}))
// drop the unique index.
mock.ExpectExec(escape("DROP INDEX `age` ON `users`")).
WillReturnResult(sqlmock.NewResult(0, 1))
@@ -758,6 +762,97 @@ func TestMySQL_Create(t *testing.T) {
mock.ExpectCommit()
},
},
{
name: "drop foreign key with column and index",
tables: []*Table{
{
Name: "users",
Columns: []*Column{
{Name: "id", Type: field.TypeInt, Increment: true},
},
PrimaryKey: []*Column{
{Name: "id", Type: field.TypeInt, Increment: true},
},
},
},
options: []MigrateOption{WithDropIndex(true), WithDropColumn(true)},
before: func(mock sqlmock.Sqlmock) {
mock.ExpectBegin()
mock.ExpectQuery(escape("SHOW VARIABLES LIKE 'version'")).
WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).AddRow("version", "5.7.23"))
mock.ExpectQuery(escape("SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
WithArgs("users").
WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
mock.ExpectQuery(escape("SELECT `column_name`, `column_type`, `is_nullable`, `column_key`, `column_default`, `extra`, `character_set_name`, `collation_name` FROM INFORMATION_SCHEMA.COLUMNS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
WithArgs("users").
WillReturnRows(sqlmock.NewRows([]string{"column_name", "column_type", "is_nullable", "column_key", "column_default", "extra", "character_set_name", "collation_name"}).
AddRow("id", "bigint(20)", "NO", "PRI", "NULL", "auto_increment", "", "").
AddRow("parent_id", "bigint(20)", "YES", "NULL", "NULL", "", "", ""))
mock.ExpectQuery(escape("SELECT `index_name`, `column_name`, `non_unique`, `seq_in_index` FROM INFORMATION_SCHEMA.STATISTICS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
WithArgs("users").
WillReturnRows(sqlmock.NewRows([]string{"index_name", "column_name", "non_unique", "seq_in_index"}).
AddRow("PRIMARY", "id", "0", "1").
AddRow("parent_id", "parent_id", "0", "1"))
// check if a foreign-key needs to be dropped.
mock.ExpectQuery(escape("SELECT `CONSTRAINT_NAME` FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE `TABLE_NAME` = ? AND `COLUMN_NAME` = ? AND `POSITION_IN_UNIQUE_CONSTRAINT` IS NOT NULL AND `TABLE_SCHEMA` = (SELECT DATABASE())")).
WithArgs("users", "parent_id").
WillReturnRows(sqlmock.NewRows([]string{"CONSTRAINT_NAME"}).AddRow("users_parent_id"))
mock.ExpectExec(escape("ALTER TABLE `users` DROP FOREIGN KEY `users_parent_id`")).
WillReturnResult(sqlmock.NewResult(0, 1))
// drop the unique index.
mock.ExpectExec(escape("DROP INDEX `parent_id` ON `users`")).
WillReturnResult(sqlmock.NewResult(0, 1))
// drop the unique index.
mock.ExpectExec(escape("ALTER TABLE `users` DROP COLUMN `parent_id`")).
WillReturnResult(sqlmock.NewResult(0, 1))
mock.ExpectCommit()
},
},
{
name: "create a new simple-index for the foreign-key",
tables: []*Table{
{
Name: "users",
Columns: []*Column{
{Name: "id", Type: field.TypeInt, Increment: true},
{Name: "parent_id", Type: field.TypeInt, Nullable: true},
},
PrimaryKey: []*Column{
{Name: "id", Type: field.TypeInt, Increment: true},
},
},
},
options: []MigrateOption{WithDropIndex(true), WithDropColumn(true)},
before: func(mock sqlmock.Sqlmock) {
mock.ExpectBegin()
mock.ExpectQuery(escape("SHOW VARIABLES LIKE 'version'")).
WillReturnRows(sqlmock.NewRows([]string{"Variable_name", "Value"}).AddRow("version", "5.7.23"))
mock.ExpectQuery(escape("SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
WithArgs("users").
WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(1))
mock.ExpectQuery(escape("SELECT `column_name`, `column_type`, `is_nullable`, `column_key`, `column_default`, `extra`, `character_set_name`, `collation_name` FROM INFORMATION_SCHEMA.COLUMNS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
WithArgs("users").
WillReturnRows(sqlmock.NewRows([]string{"column_name", "column_type", "is_nullable", "column_key", "column_default", "extra", "character_set_name", "collation_name"}).
AddRow("id", "bigint(20)", "NO", "PRI", "NULL", "auto_increment", "", "").
AddRow("parent_id", "bigint(20)", "YES", "NULL", "NULL", "", "", ""))
mock.ExpectQuery(escape("SELECT `index_name`, `column_name`, `non_unique`, `seq_in_index` FROM INFORMATION_SCHEMA.STATISTICS WHERE `TABLE_SCHEMA` = (SELECT DATABASE()) AND `TABLE_NAME` = ?")).
WithArgs("users").
WillReturnRows(sqlmock.NewRows([]string{"index_name", "column_name", "non_unique", "seq_in_index"}).
AddRow("PRIMARY", "id", "0", "1").
AddRow("parent_id", "parent_id", "0", "1"))
// check if there's a foreign-key that is associated with this index.
mock.ExpectQuery(escape("SELECT `CONSTRAINT_NAME` FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE `TABLE_NAME` = ? AND `COLUMN_NAME` = ? AND `POSITION_IN_UNIQUE_CONSTRAINT` IS NOT NULL AND `TABLE_SCHEMA` = (SELECT DATABASE())")).
WithArgs("users", "parent_id").
WillReturnRows(sqlmock.NewRows([]string{"CONSTRAINT_NAME"}).AddRow("users_parent_id"))
// create a new index, to replace the old one (that needs to be dropped).
mock.ExpectExec(escape("CREATE INDEX `users_parent_id` ON `users`(`parent_id`)")).
WillReturnResult(sqlmock.NewResult(0, 1))
// drop the unique index.
mock.ExpectExec(escape("DROP INDEX `parent_id` ON `users`")).
WillReturnResult(sqlmock.NewResult(0, 1))
mock.ExpectCommit()
},
},
{
name: "add edge to table",
tables: func() []*Table {

6
dialect/sql/schema/schema.go
View File

@@ -69,13 +69,13 @@ func (t *Table) AddIndex(name string, unique bool, columns []string) *Table {
Name: name,
Unique: unique,
columns: columns,
Columns: make([]*Column, len(columns)),
Columns: make([]*Column, 0, len(columns)),
}
for i, name := range columns {
for _, name := range columns {
c, ok := t.columns[name]
if ok {
idx.Columns[i] = c
c.indexes = append(c.indexes, idx)
idx.Columns = append(idx.Columns, c)
}
}
t.Indexes = append(t.Indexes, idx)