*: Support SHOW PLACEMENT for placement policies

executor/show.go

@@ -215,6 +215,8 @@ func (e *ShowExec) fetchAll(ctx context.Context) error {
 		return e.fetchShowBRIE(ast.BRIEKindRestore)
 	case ast.ShowPlacementLabels:
 		return e.fetchShowPlacementLabels(ctx)
+	case ast.ShowPlacement:
+		return e.fetchShowPlacement(ctx)
 	}
 	return nil
 }

executor/show_placement.go

@@ -127,3 +127,24 @@ func (e *ShowExec) fetchShowPlacementLabels(ctx context.Context) error {
 
 	return nil
 }
+
+func (e *ShowExec) fetchShowPlacement(_ context.Context) error {
+	err := e.fetchAllPlacementPolicies()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (e *ShowExec) fetchAllPlacementPolicies() error {
+	policies := e.is.AllPlacementPolicies()
+	sort.Slice(policies, func(i, j int) bool { return policies[i].Name.O < policies[j].Name.O })
+	for _, policy := range policies {
+		name := policy.Name
+		settings := policy.PlacementSettings
+		e.appendRow([]interface{}{"POLICY " + name.String(), settings.String(), "SCHEDULED"})
+	}
+
+	return nil
+}

executor/show_placement_labels_test.go

@@ -0,0 +1,85 @@
+// Copyright 2021 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package executor
+
+import (
+	gjson "encoding/json"
+
+	. "github.com/pingcap/check"
+	"github.com/pingcap/tidb/store/helper"
+	"github.com/pingcap/tidb/types/json"
+)
+
+var _ = SerialSuites(&testShowPlacementLabelSuit{})
+
+type testShowPlacementLabelSuit struct {
+}
+
+func (s *testShowPlacementLabelSuit) TestShowPlacementLabelsBuilder(c *C) {
+	cases := []struct {
+		stores  [][]*helper.StoreLabel
+		expects [][]interface{}
+	}{
+		{
+			stores:  nil,
+			expects: nil,
+		},
+		{
+			stores: [][]*helper.StoreLabel{
+				{{Key: "zone", Value: "z1"}, {Key: "rack", Value: "r3"}, {Key: "host", Value: "h1"}},
+				{{Key: "zone", Value: "z1"}, {Key: "rack", Value: "r1"}, {Key: "host", Value: "h2"}},
+				{{Key: "zone", Value: "z1"}, {Key: "rack", Value: "r2"}, {Key: "host", Value: "h2"}},
+				{{Key: "zone", Value: "z2"}, {Key: "rack", Value: "r1"}, {Key: "host", Value: "h2"}},
+				nil,
+				{{Key: "k1", Value: "v1"}},
+			},
+			expects: [][]interface{}{
+				{"host", []string{"h1", "h2"}},
+				{"k1", []string{"v1"}},
+				{"rack", []string{"r1", "r2", "r3"}},
+				{"zone", []string{"z1", "z2"}},
+			},
+		},
+	}
+
+	b := &showPlacementLabelsResultBuilder{}
+	toBinaryJSON := func(obj interface{}) (bj json.BinaryJSON) {
+		d, err := gjson.Marshal(obj)
+		c.Assert(err, IsNil)
+		err = bj.UnmarshalJSON(d)
+		c.Assert(err, IsNil)
+		return
+	}
+
+	for _, ca := range cases {
+		for _, store := range ca.stores {
+			bj := toBinaryJSON(store)
+			err := b.AppendStoreLabels(bj)
+			c.Assert(err, IsNil)
+		}
+
+		rows, err := b.BuildRows()
+		c.Assert(err, IsNil)
+		c.Assert(len(rows), Equals, len(ca.expects))
+		for idx, expect := range ca.expects {
+			row := rows[idx]
+			bj := toBinaryJSON(expect[1])
+
+			c.Assert(row[0].(string), Equals, expect[0].(string))
+			c.Assert(row[1].(json.BinaryJSON).TypeCode, Equals, bj.TypeCode)
+			c.Assert(row[1].(json.BinaryJSON).Value, BytesEquals, bj.Value)
+		}
+	}
+}

executor/show_placement_test.go

@@ -12,74 +12,55 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package executor
+package executor_test
 
 import (
-	gjson "encoding/json"
-
 	. "github.com/pingcap/check"
-	"github.com/pingcap/tidb/store/helper"
-	"github.com/pingcap/tidb/types/json"
+	"github.com/pingcap/tidb/util/testkit"
 )
 
-var _ = SerialSuites(&testShowPlacementSuit{})
+func (s *testSuite5) TestShowPlacement(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("drop placement policy if exists p1")
 
-type testShowPlacementSuit struct {
-}
+	tk.MustExec("create placement policy pa1 " +
+		"PRIMARY_REGION=\"cn-east-1\" " +
+		"REGIONS=\"cn-east-1,cn-east-2\"" +
+		"SCHEDULE=\"EVEN\"")
+	defer tk.MustExec("drop placement policy pa1")
+
+	tk.MustExec("create placement policy pa2 " +
+		"LEADER_CONSTRAINTS=\"[+region=us-east-1]\" " +
+		"FOLLOWER_CONSTRAINTS=\"[+region=us-east-2]\" " +
+		"FOLLOWERS=3")
+	defer tk.MustExec("drop placement policy pa2")
 
-func (s *testPartitionSuite) TestShowPlacementLabelsBuilder(c *C) {
-	cases := []struct {
-		stores  [][]*helper.StoreLabel
-		expects [][]interface{}
-	}{
-		{
-			stores:  nil,
-			expects: nil,
-		},
-		{
-			stores: [][]*helper.StoreLabel{
-				{{Key: "zone", Value: "z1"}, {Key: "rack", Value: "r3"}, {Key: "host", Value: "h1"}},
-				{{Key: "zone", Value: "z1"}, {Key: "rack", Value: "r1"}, {Key: "host", Value: "h2"}},
-				{{Key: "zone", Value: "z1"}, {Key: "rack", Value: "r2"}, {Key: "host", Value: "h2"}},
-				{{Key: "zone", Value: "z2"}, {Key: "rack", Value: "r1"}, {Key: "host", Value: "h2"}},
-				nil,
-				{{Key: "k1", Value: "v1"}},
-			},
-			expects: [][]interface{}{
-				{"host", []string{"h1", "h2"}},
-				{"k1", []string{"v1"}},
-				{"rack", []string{"r1", "r2", "r3"}},
-				{"zone", []string{"z1", "z2"}},
-			},
-		},
-	}
+	tk.MustExec("create placement policy pb1 " +
+		"VOTER_CONSTRAINTS=\"[+region=bj]\" " +
+		"LEARNER_CONSTRAINTS=\"[+region=sh]\" " +
+		"CONSTRAINTS=\"[+disk=ssd]\"" +
+		"VOTERS=5 " +
+		"LEARNERS=3")
+	defer tk.MustExec("drop placement policy pb1")
 
-	b := &showPlacementLabelsResultBuilder{}
-	toBinaryJSON := func(obj interface{}) (bj json.BinaryJSON) {
-		d, err := gjson.Marshal(obj)
-		c.Assert(err, IsNil)
-		err = bj.UnmarshalJSON(d)
-		c.Assert(err, IsNil)
-		return
-	}
+	tk.MustQuery("show placement").Check(testkit.Rows(
+		"POLICY pa1 PRIMARY_REGION=\"cn-east-1\" REGIONS=\"cn-east-1,cn-east-2\" SCHEDULE=\"EVEN\" SCHEDULED",
+		"POLICY pa2 LEADER_CONSTRAINTS=\"[+region=us-east-1]\" FOLLOWERS=3 FOLLOWER_CONSTRAINTS=\"[+region=us-east-2]\" SCHEDULED",
+		"POLICY pb1 CONSTRAINTS=\"[+disk=ssd]\" VOTERS=5 VOTER_CONSTRAINTS=\"[+region=bj]\" LEARNERS=3 LEARNER_CONSTRAINTS=\"[+region=sh]\" SCHEDULED",
+	))
 
-	for _, ca := range cases {
-		for _, store := range ca.stores {
-			bj := toBinaryJSON(store)
-			err := b.AppendStoreLabels(bj)
-			c.Assert(err, IsNil)
-		}
+	tk.MustQuery("show placement like 'POLICY%'").Check(testkit.Rows(
+		"POLICY pa1 PRIMARY_REGION=\"cn-east-1\" REGIONS=\"cn-east-1,cn-east-2\" SCHEDULE=\"EVEN\" SCHEDULED",
+		"POLICY pa2 LEADER_CONSTRAINTS=\"[+region=us-east-1]\" FOLLOWERS=3 FOLLOWER_CONSTRAINTS=\"[+region=us-east-2]\" SCHEDULED",
+		"POLICY pb1 CONSTRAINTS=\"[+disk=ssd]\" VOTERS=5 VOTER_CONSTRAINTS=\"[+region=bj]\" LEARNERS=3 LEARNER_CONSTRAINTS=\"[+region=sh]\" SCHEDULED",
+	))
 
-		rows, err := b.BuildRows()
-		c.Assert(err, IsNil)
-		c.Assert(len(rows), Equals, len(ca.expects))
-		for idx, expect := range ca.expects {
-			row := rows[idx]
-			bj := toBinaryJSON(expect[1])
+	tk.MustQuery("show placement like 'POLICY pa%'").Check(testkit.Rows(
+		"POLICY pa1 PRIMARY_REGION=\"cn-east-1\" REGIONS=\"cn-east-1,cn-east-2\" SCHEDULE=\"EVEN\" SCHEDULED",
+		"POLICY pa2 LEADER_CONSTRAINTS=\"[+region=us-east-1]\" FOLLOWERS=3 FOLLOWER_CONSTRAINTS=\"[+region=us-east-2]\" SCHEDULED",
+	))
 
-			c.Assert(row[0].(string), Equals, expect[0].(string))
-			c.Assert(row[1].(json.BinaryJSON).TypeCode, Equals, bj.TypeCode)
-			c.Assert(row[1].(json.BinaryJSON).Value, BytesEquals, bj.Value)
-		}
-	}
+	tk.MustQuery("show placement where Target='POLICY pb1'").Check(testkit.Rows(
+		"POLICY pb1 CONSTRAINTS=\"[+disk=ssd]\" VOTERS=5 VOTER_CONSTRAINTS=\"[+region=bj]\" LEARNERS=3 LEARNER_CONSTRAINTS=\"[+region=sh]\" SCHEDULED",
+	))
 }

infoschema/infoschema.go

@@ -58,6 +58,8 @@ type InfoSchema interface {
 	SetBundle(*placement.Bundle)
 	// RuleBundles will return a copy of all rule bundles.
 	RuleBundles() []*placement.Bundle
+	// AllPlacementPolicies returns all placement policies
+	AllPlacementPolicies() []*placementpolicy.PolicyInfo
 }
 
 type sortedTables []table.Table
@@ -406,6 +408,13 @@ func (is *infoSchema) SetBundle(bundle *placement.Bundle) {
 	is.ruleBundleMap[bundle.ID] = bundle
 }
 
+func (is *infoSchema) AllPlacementPolicies() (policies []*placementpolicy.PolicyInfo) {
+	for _, p := range is.policyMap {
+		policies = append(policies, p)
+	}
+	return
+}
+
 func (is *infoSchema) deleteBundle(id string) {
 	is.ruleBundleMutex.Lock()
 	defer is.ruleBundleMutex.Unlock()

meta/meta_test.go

@@ -52,15 +52,17 @@ func TestPlacementPolicy(t *testing.T) {
 
 	// test the meta storage of placemnt policy.
 	policy := &placementpolicy.PolicyInfo{
-		Name:               model.NewCIStr("aa"),
-		PrimaryRegion:      "my primary",
-		Regions:            "my regions",
-		Learners:           1,
-		Followers:          2,
-		Voters:             3,
-		Schedule:           "even",
-		Constraints:        "+disk=ssd",
-		LearnerConstraints: "+zone=shanghai",
+		Name: model.NewCIStr("aa"),
+		PlacementSettings: placementpolicy.PlacementSettings{
+			PrimaryRegion:      "my primary",
+			Regions:            "my regions",
+			Learners:           1,
+			Followers:          2,
+			Voters:             3,
+			Schedule:           "even",
+			Constraints:        "+disk=ssd",
+			LearnerConstraints: "+zone=shanghai",
+		},
 	}
 	err = m.CreatePolicy(policy)
 	require.NoError(t, err)

planner/core/planbuilder.go

@@ -4127,6 +4127,9 @@ func buildShowSchema(s *ast.ShowStmt, isView bool, isSequence bool) (schema *exp
 	case ast.ShowPlacementLabels:
 		names = []string{"Key", "Values"}
 		ftypes = []byte{mysql.TypeVarchar, mysql.TypeJSON}
+	case ast.ShowPlacement:
+		names = []string{"Target", "Placement", "Scheduling_state"}
+		ftypes = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar}
 	}
 
 	schema = expression.NewSchema(make([]*expression.Column, 0, len(names))...)

util/placementpolicy/policy.go

@@ -15,23 +15,80 @@
 package placementpolicy
 
 import (
+	"fmt"
+	"strings"
+
 	"github.com/pingcap/parser/model"
 )
 
+// PlacementSettings is the settings of the placement
+type PlacementSettings struct {
+	PrimaryRegion       string `json:"primary_region"`
+	Regions             string `json:"regions"`
+	Learners            uint64 `json:"learners"`
+	Followers           uint64 `json:"followers"`
+	Voters              uint64 `json:"voters"`
+	Schedule            string `json:"schedule"`
+	Constraints         string `json:"constraints"`
+	LeaderConstraints   string `json:"leader_constraints"`
+	LearnerConstraints  string `json:"learner_constraints"`
+	FollowerConstraints string `json:"follower_constraints"`
+	VoterConstraints    string `json:"voter_constraints"`
+}
+
+func (p *PlacementSettings) String() string {
+	settings := make([]string, 0)
+	if len(p.PrimaryRegion) > 0 {
+		settings = append(settings, fmt.Sprintf("PRIMARY_REGION=\"%s\"", p.PrimaryRegion))
+	}
+
+	if len(p.Regions) > 0 {
+		settings = append(settings, fmt.Sprintf("REGIONS=\"%s\"", p.Regions))
+	}
+
+	if len(p.Schedule) > 0 {
+		settings = append(settings, fmt.Sprintf("SCHEDULE=\"%s\"", p.Schedule))
+	}
+
+	if len(p.Constraints) > 0 {
+		settings = append(settings, fmt.Sprintf("CONSTRAINTS=\"%s\"", p.Constraints))
+	}
+
+	if len(p.LeaderConstraints) > 0 {
+		settings = append(settings, fmt.Sprintf("LEADER_CONSTRAINTS=\"%s\"", p.LeaderConstraints))
+	}
+
+	if p.Voters > 0 {
+		settings = append(settings, fmt.Sprintf("VOTERS=%d", p.Voters))
+	}
+
+	if len(p.VoterConstraints) > 0 {
+		settings = append(settings, fmt.Sprintf("VOTER_CONSTRAINTS=\"%s\"", p.VoterConstraints))
+	}
+
+	if p.Followers > 0 {
+		settings = append(settings, fmt.Sprintf("FOLLOWERS=%d", p.Followers))
+	}
+
+	if len(p.FollowerConstraints) > 0 {
+		settings = append(settings, fmt.Sprintf("FOLLOWER_CONSTRAINTS=\"%s\"", p.FollowerConstraints))
+	}
+
+	if p.Learners > 0 {
+		settings = append(settings, fmt.Sprintf("LEARNERS=%d", p.Learners))
+	}
+
+	if len(p.LearnerConstraints) > 0 {
+		settings = append(settings, fmt.Sprintf("LEARNER_CONSTRAINTS=\"%s\"", p.LearnerConstraints))
+	}
+
+	return strings.Join(settings, " ")
+}
+
 // PolicyInfo is the struct to store the placement policy.
 type PolicyInfo struct {
-	ID                  int64             `json:"id"`
-	Name                model.CIStr       `json:"name"`
-	PrimaryRegion       string            `json:"primary_region"`
-	Regions             string            `json:"regions"`
-	Learners            uint64            `json:"learners"`
-	Followers           uint64            `json:"followers"`
-	Voters              uint64            `json:"voters"`
-	Schedule            string            `json:"schedule"`
-	Constraints         string            `json:"constraints"`
-	LeaderConstraints   string            `json:"leader_constraints"`
-	LearnerConstraints  string            `json:"learner_constraints"`
-	FollowerConstraints string            `json:"follower_constraints"`
-	VoterConstraints    string            `json:"voter_constraints"`
-	State               model.SchemaState `json:"state"`
+	PlacementSettings
+	ID    int64             `json:"id"`
+	Name  model.CIStr       `json:"name"`
+	State model.SchemaState `json:"state"`
 }