sql: add SET CLUSTER SETTING wrapper to alter system.settings

Currently a very thin wrapper around just upserting strings, just to get the various boilerplate and plumbing in place.

pkg/sql/set.go

@@ -17,11 +17,11 @@
 package sql
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 	"time"
 
+	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 
 	"github.com/cockroachdb/apd"
@@ -40,6 +40,13 @@ func (p *planner) Set(ctx context.Context, n *parser.Set) (planNode, error) {
 		return nil, errors.New("invalid statement: SET ROW")
 	}
 
+	name := n.Name.String()
+	setMode := n.SetMode
+
+	if setMode == parser.SetModeClusterSetting {
+		return p.setClusterSetting(ctx, name, n.Values)
+	}
+
 	// By using VarName.String() here any variables that are keywords will
 	// be double quoted.
 	typedValues := make([]parser.TypedExpr, len(n.Values))
@@ -51,14 +58,11 @@ func (p *planner) Set(ctx context.Context, n *parser.Set) (planNode, error) {
 		typedValues[i] = typedValue
 	}
 
-	name := n.Name.String()
-
 	v, ok := varGen[strings.ToLower(name)]
 	if !ok {
 		return nil, fmt.Errorf("unknown variable: %q", name)
 	}
 
-	setMode := n.SetMode
 	if len(n.Values) == 0 {
 		setMode = parser.SetModeReset
 	}
@@ -83,6 +87,53 @@ func (p *planner) Set(ctx context.Context, n *parser.Set) (planNode, error) {
 	return &emptyNode{}, nil
 }
 
+func (p *planner) setClusterSetting(
+	ctx context.Context, name string, v []parser.Expr,
+) (planNode, error) {
+	if err := p.RequireSuperUser("SET CLUSTER SETTING"); err != nil {
+		return nil, err
+	}
+	name = strings.ToLower(name)
+	ie := InternalExecutor{LeaseManager: p.LeaseMgr()}
+
+	switch len(v) {
+	case 0:
+		if _, err := ie.ExecuteStatementInTransaction(
+			ctx, "update-setting", p.txn, "DELETE FROM system.settings WHERE name = $1", name,
+		); err != nil {
+			return nil, err
+		}
+	case 1:
+		// TODO(dt): validate and properly encode str according to type.
+		encoded, err := p.toSettingString(v[0])
+		if err != nil {
+			return nil, err
+		}
+		upsertQ := "UPSERT INTO system.settings (name, value, lastUpdated, valueType) VALUES ($1, $2, NOW(), $3)"
+		if _, err := ie.ExecuteStatementInTransaction(
+			ctx, "update-setting", p.txn, upsertQ, name, encoded, "s",
+		); err != nil {
+			return nil, err
+		}
+	default:
+		return nil, errors.Errorf("SET %q requires a single value", name)
+	}
+	return &emptyNode{}, nil
+}
+
+func (p *planner) toSettingString(raw parser.Expr) (string, error) {
+	// TODO(dt): typecheck and handle according to setting's desired type.
+	typed, err := parser.TypeCheckAndRequire(raw, nil, parser.TypeString, "SET")
+	if err != nil {
+		return "", err
+	}
+	d, err := typed.Eval(&p.evalCtx)
+	if err != nil {
+		return "", err
+	}
+	return string(parser.MustBeDString(d)), nil
+}
+
 func (p *planner) getStringVal(name string, values []parser.TypedExpr) (string, error) {
 	if len(values) != 1 {
 		return "", fmt.Errorf("set %s: requires a single string value", name)

pkg/sql/testdata/logic_test/set

@@ -196,3 +196,51 @@ server_version
 # Test read-only variables
 statement error variable "max_index_keys" cannot be changed
 SET max_index_keys = 32
+
+query TT
+SELECT name, value FROM system.settings WHERE name = 'foo'
+----
+
+user testuser
+statement error only root is allowed to SET CLUSTER SETTING
+SET CLUSTER SETTING foo = 'bar'
+
+user root
+
+query TT
+SELECT name, value FROM system.settings WHERE name = 'foo'
+----
+
+statement ok
+SET CLUSTER SETTING foo = 'bar'
+
+query TT
+SELECT name, value FROM system.settings WHERE name = 'foo'
+----
+foo   bar
+
+statement ok
+SET CLUSTER SETTING foo = 'baz'
+
+query TT
+SELECT name, value FROM system.settings WHERE name = 'foo'
+----
+foo   baz
+
+user testuser
+statement error only root is allowed to SET CLUSTER SETTING
+SET CLUSTER SETTING foo = 'bar'
+
+user root
+
+query TT
+SELECT name, value FROM system.settings WHERE name = 'foo'
+----
+foo   baz
+
+statement ok
+SET CLUSTER SETTING foo TO DEFAULT
+
+query TT
+SELECT name, value FROM system.settings WHERE name = 'foo'
+----