update: optimize mysql v8.0 ddl instant check (#668)

config/config.go

@@ -304,6 +304,8 @@ type Inc struct {
 	EnableSetCollation bool `toml:"enable_set_collation" json:"enable_set_collation"`
 	// 开启sql统计
 	EnableSqlStatistic bool `toml:"enable_sql_statistic" json:"enable_sql_statistic"`
+	// 在MySQL8.0检测是否支持 ALGORITHM=INSTANT, 当支持时自动关闭pt-osc/gh-ost.
+	EnableDDLInstant bool `toml:"enable_ddl_instant" json:"enable_ddl_instant"`
 
 	// explain判断受影响行数时使用的规则, 默认值"first"
 	// 可选值: "first", "max"
@@ -703,6 +705,7 @@ var defaultConf = Config{
 		CheckIdentifierUpper:  false,
 		CheckIdentifierLower:  false,
 		CheckReadOnly:         true,
+		EnableDDLInstant:      true,
 		SqlSafeUpdates:        -1,
 		LockWaitTimeout:       -1,
 		SupportCharset:        "utf8,utf8mb4",

config/config.toml.default

@@ -61,6 +61,8 @@ check_float_double = false
 check_identifier_upper = false
 check_identifier_lower = false
 check_read_only = true
+# 在MySQL8.0检测是否支持ALGORITHM=INSTANT, 当支持时自动关闭pt-osc/gh-ost.
+enable_ddl_instant = true
 
 # 是否检查字段存在多个索引，比如索引 (a,b) 与索引 (a) 中，a字段就是被重复索引的，应当只保留索引 (a,b)
 check_index_column_repeat = false

session/session_inception.go

@@ -3354,13 +3354,13 @@
 
 	// 设置osc开关
 	s.checkAlterUseOsc(table)
+	s.checkDDLInstant(node, table)
 
 	// 如果修改了表名,则调整回滚语句
 	hasRenameTable := false
 	for _, alter := range node.Specs {
 		if alter.Tp == ast.AlterTableRenameTable {
 			hasRenameTable = true
-			s.myRecord.useOsc = false
 			break
 		}
 	}
@@ -3423,6 +3423,7 @@
 		s.appendErrorNo(ER_NOT_SUPPORTED_YET)
 		return
 	}
+
 	for i, alter := range node.Specs {
 		switch alter.Tp {
 		case ast.AlterTableOption:
@@ -3610,6 +3611,123 @@
 	}
 }
 
+// checkDDLInstant 检查是否支持 ALGORITHM=INSTANT, 当支持时自动关闭pt-osc/gh-ost.
+func (s *session) checkDDLInstant(node *ast.AlterTableStmt, t *TableInfo) {
+	if !s.inc.EnableDDLInstant || !s.myRecord.useOsc || s.dbVersion < 50700 {
+		return
+	}
+
+	if s.dbVersion < 80000 {
+		// 如果mysql版本小于8.0,只有VIRTUAL column支持Only Modifies Metadata
+		for _, alter := range node.Specs {
+			switch alter.Tp {
+			case ast.AlterTableAddColumns:
+				newColumns := len(alter.NewColumns)
+				virtualColumns := 0
+				for _, nc := range alter.NewColumns {
+					isPrimary := false
+					isUnique := false
+					var isStore *bool
+					for _, op := range nc.Options {
+						switch op.Tp {
+						case ast.ColumnOptionPrimaryKey:
+							isPrimary = true
+						case ast.ColumnOptionUniqKey:
+							isUnique = true
+						case ast.ColumnOptionGenerated:
+							isStore = &op.Stored
+						}
+					}
+
+					if !isPrimary && !isUnique {
+						if s.dbVersion < 80000 && isStore != nil && !*isStore {
+							virtualColumns++
+						}
+					}
+				}
+				if virtualColumns == newColumns {
+					s.myRecord.useOsc = false
+					return
+				}
+			default:
+				return
+			}
+		}
+		return
+	}
+
+	canInstantSpecs := 0
+	for _, alter := range node.Specs {
+		// 当用户指定了 ALGORITHM=INSTANT 时,忽略检查并关闭osc
+		if alter.Algorithm == ast.AlgorithmTypeInstant {
+			s.myRecord.useOsc = false
+			return
+		}
+		switch alter.Tp {
+		case ast.AlterTableAddColumns:
+			newColumns := len(alter.NewColumns)
+			virtualColumns := 0
+			for _, nc := range alter.NewColumns {
+				isPrimary := false
+				isUnique := false
+				var isStore *bool
+				for _, op := range nc.Options {
+					switch op.Tp {
+					case ast.ColumnOptionPrimaryKey:
+						isPrimary = true
+					case ast.ColumnOptionUniqKey:
+						isUnique = true
+					case ast.ColumnOptionGenerated:
+						isStore = &op.Stored
+					}
+				}
+
+				if !isPrimary && !isUnique {
+					// 此时已经排除主键/唯一键的情况
+					// 8.0版本下只有STORED column不支持Only Modifies Metadata
+					if isStore == nil || !*isStore {
+						virtualColumns++
+					}
+				}
+			}
+			if alter.Position.Tp != ast.ColumnPositionNone {
+				if s.dbVersion < 80029 {
+					return
+				} else {
+					canInstantSpecs++
+				}
+			}
+			if virtualColumns == newColumns {
+				canInstantSpecs++
+			} else {
+				return
+			}
+
+		case ast.AlterTableDropColumn:
+			for _, field := range t.Fields {
+				if strings.EqualFold(field.Field, alter.OldColumnName.Name.O) && !field.IsDeleted {
+					if strings.Contains(field.Extra, "VIRTUAL") {
+						canInstantSpecs++
+					}
+					break
+				}
+			}
+
+		case ast.AlterTableRenameTable:
+			canInstantSpecs++
+
+		case ast.AlterTableAlterColumn:
+			canInstantSpecs++
+
+		default:
+			return
+		}
+	}
+	if canInstantSpecs == len(node.Specs) {
+		s.myRecord.useOsc = false
+	}
+}
+
 func (s *session) checkMultiPartitionParts(specs []*ast.AlterTableSpec) {
 	if len(specs) <= 1 {
 		return
@@ -4902,15 +5020,12 @@
 			if !s.hasError() {
 				isPrimary := false
 				isUnique := false
-				var isStore *bool
 				for _, op := range nc.Options {
 					switch op.Tp {
 					case ast.ColumnOptionPrimaryKey:
 						isPrimary = true
 					case ast.ColumnOptionUniqKey:
 						isUnique = true
-					case ast.ColumnOptionGenerated:
-						isStore = &op.Stored
 					}
 				}
 
@@ -4960,16 +5075,6 @@
 						}
 						t.Indexes = append(t.Indexes, index)
 					}
-				} else {
-					// 此时已经排除主键/唯一键的情况
-					// 8.0版本下只有STORED column不支持Only Modifies Metadata
-					if s.dbVersion >= 80000 && (nil == isStore || !*isStore) {
-						s.myRecord.useOsc = false
-					}
-					// 如果mysql版本小于8.0,只有VIRTUAL column支持Only Modifies Metadata
-					if s.dbVersion < 80000 && nil != isStore && !*isStore {
-						s.myRecord.useOsc = false
-					}
 				}
 			}