improve the usability of DDL Job.Args

[lance6716]

Enhancement

Currently Job.Args is like a type-erasure field

tidb/pkg/parser/model/ddl.go

Lines 514 to 522 in fedf3b7

	// Note: it might change when state changes, such as when rollback on AddColumn.
	// - CreateTable, it's [model.TableInfo, foreignKeyCheck]
	// - AddIndex or AddPrimaryKey: [unique, ....
	// - TruncateTable: [new-table-id, foreignKeyCheck, ...
	// - RenameTable: [old-db-id, new-table-name, old-db-name]
	// - ExchangeTablePartition: [partition-id, pt-db-id, pt-id, partition-name, with-validation]
	Args []interface{} `json:"-"`
	// RawArgs : We must use json raw message to delay parsing special args.
	RawArgs json.RawMessage `json:"raw_args"`

It's hard to find all usage of a DDL job type arguments and maintain them.

idea 1: I think it's better to have a specialized struct for each DDL job type. So the developer can directly find all usage of a DDL job type among all types.

idea 2: don't change old format of the serialized Job.RawArgs, the new structs should handle the serialization/deserialization in the old format. The advantage is we don't need to handle the compatibility of DDL jobs written by old version clusters.

Tasks

• *: move annotated attributes of AST node to resolve.Context #55634
• *: move XXInfo/Job, etc, out from model pkg in parser to meta #55754
• ddl: add job version 2 and use typed args for truncate table #55854
• ddl: args v2 for create/drop/modify schema #55919
• ddl: args v2 for create table/view/sequence, batch create table #55964
• ddl: args v2 for create/alter/drop resource group #56153
• ddl: args v2 for Alter/Remove Partitioning and Add/Drop/Reorganize Partition #56163
• ddl: args v2 for drop table/view/sequence #56219
• ddl: fix panic in TablePartitionArgs v2 #56222
• ddl: detect tidb version to determine job version to use, add scripts to run V1 separately #56242
• ddl: args v2 for truncate/exchange/alter partition #56269
• ddl: use JobArgs in job wrapper and use doDDLJob2 for some job type #56400
• ddl: use golang tags to force job args v1 in CI #56417
• ddl: args v2 for rename tables #55946
• ddl: args v2 for add/drop/alter CheckConstraint #56010
• ddl: args v2 for add/drop/rename index, include PK/vector-index #56130
• ddl: arg v2 for modify column and multi schema change #56536
• ddl: args v2 for create/alter/drop placement policy  #56186
• ddl: args v2 for lock/unlock/repair table and recover table/schema #56194
• ddl: arg v2 for flashback cluster and alter table attributes #56290
• ddl: refactor the args for the DDL type of renametable #55959
• ddl: refactor V2 job args of dropping column DDL. #56021
• ddl: refactor V2 args for RebaseAutoID/Modify-table/Index-visibility/FK related DDL. #56164
• ddl: refactor job args for alter sequence/auto-id-cache/shard-rowid/cache/ttl related ddl job. #56206
• ddl: refactor job args for set/update tiflash-replica and alter-table-placement ddl #56241
• ddl: refactor job args for set-default-value/add column ddl. #56337

[lance6716]

And for one type of DDL jobs, the Args may change so the marshal field RawArgs is hard to maintain

For example, DROP DATABASE will have a bool as Args at first

tidb/pkg/ddl/ddl_api.go

Lines 685 to 687 in d19fc99

	Type: model.ActionDropSchema,
	BinlogInfo: &model.HistoryInfo{},
	Args: []any{fkCheck},

but somehow it becomes []int64

tidb/pkg/ddl/delete_range.go

Lines 284 to 286 in d19fc99

	case model.ActionDropSchema:
	var tableIDs []int64
	if err := job.DecodeArgs(&tableIDs); err != nil {