*: 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{}{name.String(), settings.String(), "SCHEDULED"})
+	}
+
+	return nil
+}

infoschema/infoschema.go

@@ -57,6 +57,8 @@ 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
@@ -395,6 +397,13 @@ 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

@@ -15,22 +15,75 @@
 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"`
+	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 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))
+	}
+
+	if len(p.Constraints) > 0 {
+		settings = append(settings, fmt.Sprintf("CONSTRAINTS=\"%s\"", p.Constraints))
+	}
+
+	if len(p.Schedule) > 0 {
+		settings = append(settings, fmt.Sprintf("SCHEDULE=\"%s\"", p.Schedule))
+	}
+
+	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"`
-	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"`
 }

util/placementpolicy/policy_test.go

@@ -0,0 +1,51 @@
+// 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 placementpolicy
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPlacementSettingsString(t *testing.T) {
+	assert := assert.New(t)
+
+	settings := &PlacementSettings{
+		PrimaryRegion: "us-east-1",
+		Regions:       "us-east-1,us-east-2",
+		Voters:        2,
+	}
+	assert.Equal("PRIMARY_REGION=\"us-east-1\" REGIONS=\"us-east-1,us-east-2\" VOTERS=2", settings.String())
+
+	settings = &PlacementSettings{
+		Voters:              1,
+		VoterConstraints:    "[+region=us-east-1]",
+		Followers:           2,
+		FollowerConstraints: "[+disk=ssd]",
+		Learners:            3,
+		LearnerConstraints:  "[+region=us-east-2]",
+		Schedule:            "EVEN",
+	}
+	assert.Equal("VOTERS=1 VOTER_CONSTRAINTS=\"[+region=us-east-1]\" FOLLOWERS=2 FOLLOWER_CONSTRAINTS=\"[+disk=ssd]\" LEARNERS=3 LEARNER_CONSTRAINTS=\"[+region=us-east-2]\" SCHEDULE=\"EVEN\"", settings.String())
+
+	settings = &PlacementSettings{
+		Voters:      3,
+		Followers:   2,
+		Learners:    1,
+		Constraints: "{+us-east-1:1,+us-east-2:1}",
+	}
+	assert.Equal("VOTERS=3 FOLLOWERS=2 LEARNERS=1 CONSTRAINTS=\"{+us-east-1:1,+us-east-2:1}\"", settings.String())
+}