*: support 'admin show ddl jobs <number>' grammar

ast/misc.go

@@ -630,10 +630,11 @@ type HandleRange struct {
 type AdminStmt struct {
 	stmtNode
 
-	Tp     AdminStmtType
-	Index  string
-	Tables []*TableName
-	JobIDs []int64
+	Tp        AdminStmtType
+	Index     string
+	Tables    []*TableName
+	JobIDs    []int64
+	JobNumber int64
 
 	HandleRanges []HandleRange
 }

executor/builder.go

@@ -208,6 +208,7 @@ func (b *executorBuilder) buildShowDDL(v *plan.ShowDDL) Executor {
 
 func (b *executorBuilder) buildShowDDLJobs(v *plan.ShowDDLJobs) Executor {
 	e := &ShowDDLJobsExec{
+		jobNumber:    v.JobNumber,
 		is:           b.is,
 		baseExecutor: newBaseExecutor(b.ctx, v.Schema(), v.ExplainID()),
 	}

executor/executor.go

@@ -221,9 +221,10 @@ func (e *ShowDDLExec) Next(ctx context.Context, chk *chunk.Chunk) error {
 type ShowDDLJobsExec struct {
 	baseExecutor
 
-	cursor int
-	jobs   []*model.Job
-	is     infoschema.InfoSchema
+	cursor    int
+	jobs      []*model.Job
+	jobNumber int64
+	is        infoschema.InfoSchema
 }
 
 // ShowDDLJobQueriesExec represents a show DDL job queries executor.
@@ -247,7 +248,7 @@ func (e *ShowDDLJobQueriesExec) Open(ctx context.Context) error {
 		return errors.Trace(err)
 	}
 	// TODO: need to return the job that the user needs.
-	historyJobs, err := admin.GetHistoryDDLJobs(e.ctx.Txn())
+	historyJobs, err := admin.GetHistoryDDLJobs(e.ctx.Txn(), admin.DefHistoryJobs)
 	if err != nil {
 		return errors.Trace(err)
 	}
@@ -288,8 +289,10 @@ func (e *ShowDDLJobsExec) Open(ctx context.Context) error {
 	if err != nil {
 		return errors.Trace(err)
 	}
-
-	historyJobs, err := admin.GetHistoryDDLJobs(e.ctx.Txn())
+	if e.jobNumber == 0 {
+		e.jobNumber = 10
+	}
+	historyJobs, err := admin.GetHistoryDDLJobs(e.ctx.Txn(), int(e.jobNumber))
 	if err != nil {
 		return errors.Trace(err)
 	}

executor/executor_test.go

@@ -181,13 +181,23 @@ func (s *testSuite) TestAdmin(c *C) {
 	c.Assert(row.Len(), Equals, 10)
 	txn, err = s.store.Begin()
 	c.Assert(err, IsNil)
-	historyJobs, err := admin.GetHistoryDDLJobs(txn)
+	historyJobs, err := admin.GetHistoryDDLJobs(txn, admin.DefHistoryJobs)
 	c.Assert(len(historyJobs), Greater, 1)
 	c.Assert(len(row.GetString(1)), Greater, 0)
 	c.Assert(err, IsNil)
 	c.Assert(row.GetInt64(0), Equals, historyJobs[0].ID)
 	c.Assert(err, IsNil)
 
+	r, err = tk.Exec("admin show ddl jobs 20")
+	c.Assert(err, IsNil)
+	chk = r.NewChunk()
+	err = r.Next(ctx, chk)
+	c.Assert(err, IsNil)
+	row = chk.GetRow(0)
+	c.Assert(row.Len(), Equals, 10)
+	c.Assert(row.GetInt64(0), Equals, historyJobs[0].ID)
+	c.Assert(err, IsNil)
+
 	// show DDL job queries test
 	tk.MustExec("use test")
 	tk.MustExec("drop table if exists admin_test2")
@@ -196,7 +206,7 @@ func (s *testSuite) TestAdmin(c *C) {
 	result.Check(testkit.Rows())
 	result = tk.MustQuery(`admin show ddl job queries 1, 2, 3, 4`)
 	result.Check(testkit.Rows())
-	historyJob, err := admin.GetHistoryDDLJobs(txn)
+	historyJob, err := admin.GetHistoryDDLJobs(txn, admin.DefHistoryJobs)
 	result = tk.MustQuery(fmt.Sprintf("admin show ddl job queries %d", historyJob[0].ID))
 	result.Check(testkit.Rows(historyJob[0].Query))
 	c.Assert(err, IsNil)

parser/parser.y

@@ -5089,6 +5089,13 @@ AdminStmt:
 	{
 		$$ = &ast.AdminStmt{Tp: ast.AdminShowDDLJobs}
 	}
+|	"ADMIN" "SHOW" "DDL" "JOBS" NUM
+	{
+		$$ = &ast.AdminStmt{
+		    Tp: ast.AdminShowDDLJobs,
+		    JobNumber: $5.(int64),
+		}
+	}
 |	"ADMIN" "CHECK" "TABLE" TableNameList
 	{
 		$$ = &ast.AdminStmt{

parser/parser_test.go

@@ -413,6 +413,7 @@ func (s *testParserSuite) TestDMLStmt(c *C) {
 		// for admin
 		{"admin show ddl;", true},
 		{"admin show ddl jobs;", true},
+		{"admin show ddl jobs 20;", true},
 		{"admin show ddl job queries 1", true},
 		{"admin show ddl job queries 1, 2, 3, 4", true},
 		{"admin check table t1, t2;", true},

plan/common_plans.go

@@ -39,6 +39,8 @@ type ShowDDL struct {
 // ShowDDLJobs is for showing DDL job list.
 type ShowDDLJobs struct {
 	baseSchemaProducer
+
+	JobNumber int64
 }
 
 // ShowDDLJobQueries is for showing DDL job queries sql.

plan/planbuilder.go

@@ -469,7 +469,7 @@ func (b *planBuilder) buildAdmin(as *ast.AdminStmt) Plan {
 		p.SetSchema(buildShowDDLFields())
 		ret = p
 	case ast.AdminShowDDLJobs:
-		p := &ShowDDLJobs{}
+		p := &ShowDDLJobs{JobNumber: as.JobNumber}
 		p.SetSchema(buildShowDDLJobsFields())
 		ret = p
 	case ast.AdminCancelDDLJobs:

util/admin/admin.go

@@ -137,18 +137,21 @@ func GetDDLJobs(txn kv.Transaction) ([]*model.Job, error) {
 // MaxHistoryJobs is exported for testing.
 const MaxHistoryJobs = 10
 
+// DefHistoryJobs is default value of the default number of history job
+const DefHistoryJobs = 10
+
 // GetHistoryDDLJobs returns the DDL history jobs and an error.
-// The maximum count of history jobs is MaxHistoryJobs.
-func GetHistoryDDLJobs(txn kv.Transaction) ([]*model.Job, error) {
+// The maximum count of history jobs is num.
+func GetHistoryDDLJobs(txn kv.Transaction, num int) ([]*model.Job, error) {
 	t := meta.NewMeta(txn)
 	jobs, err := t.GetAllHistoryDDLJobs()
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
 
 	jobsLen := len(jobs)
-	if jobsLen > MaxHistoryJobs {
-		start := jobsLen - MaxHistoryJobs
+	if jobsLen > num {
+		start := jobsLen - num
 		jobs = jobs[start:]
 	}
 	jobsLen = len(jobs)

util/admin/admin_test.go

@@ -172,7 +172,7 @@ func (s *testSuite) TestGetHistoryDDLJobs(c *C) {
 		}
 		err = t.AddHistoryDDLJob(jobs[i])
 		c.Assert(err, IsNil)
-		historyJobs, err1 := GetHistoryDDLJobs(txn)
+		historyJobs, err1 := GetHistoryDDLJobs(txn, DefHistoryJobs)
 		c.Assert(err1, IsNil)
 		if i+1 > MaxHistoryJobs {
 			c.Assert(historyJobs, HasLen, MaxHistoryJobs)
@@ -182,7 +182,7 @@ func (s *testSuite) TestGetHistoryDDLJobs(c *C) {
 	}
 
 	delta := cnt - MaxHistoryJobs
-	historyJobs, err := GetHistoryDDLJobs(txn)
+	historyJobs, err := GetHistoryDDLJobs(txn, DefHistoryJobs)
 	c.Assert(err, IsNil)
 	c.Assert(historyJobs, HasLen, MaxHistoryJobs)
 	l := len(historyJobs) - 1