comment_on_database.go

// Copyright 2018 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

package sql

import (
	"context"

	"github.com/cockroachdb/cockroach/pkg/keys"
	"github.com/cockroachdb/cockroach/pkg/security"
	"github.com/cockroachdb/cockroach/pkg/sql/catalog"
	"github.com/cockroachdb/cockroach/pkg/sql/privilege"
	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
	"github.com/cockroachdb/cockroach/pkg/sql/sessiondata"
	"github.com/cockroachdb/cockroach/pkg/util/log/eventpb"
)

type commentOnDatabaseNode struct {
	n      *tree.CommentOnDatabase
	dbDesc catalog.DatabaseDescriptor
}

// CommentOnDatabase add comment on a database.
// Privileges: CREATE on database.
//   notes: postgres requires CREATE on the database.
func (p *planner) CommentOnDatabase(
	ctx context.Context, n *tree.CommentOnDatabase,
) (planNode, error) {
	if err := checkSchemaChangeEnabled(
		ctx,
		p.ExecCfg(),
		"COMMENT ON DATABASE",
	); err != nil {
		return nil, err
	}

	dbDesc, err := p.Descriptors().GetImmutableDatabaseByName(ctx, p.txn,
		string(n.Name), tree.DatabaseLookupFlags{Required: true})
	if err != nil {
		return nil, err
	}
	if err := p.CheckPrivilege(ctx, dbDesc, privilege.CREATE); err != nil {
		return nil, err
	}

	return &commentOnDatabaseNode{n: n, dbDesc: dbDesc}, nil
}

func (n *commentOnDatabaseNode) startExec(params runParams) error {
	if n.n.Comment != nil {
		_, err := params.p.extendedEvalCtx.ExecCfg.InternalExecutor.ExecEx(
			params.ctx,
			"set-db-comment",
			params.p.Txn(),
			sessiondata.InternalExecutorOverride{User: security.RootUserName()},
			"UPSERT INTO system.comments VALUES ($1, $2, 0, $3)",
			keys.DatabaseCommentType,
			n.dbDesc.GetID(),
			*n.n.Comment)
		if err != nil {
			return err
		}
	} else {
		_, err := params.p.extendedEvalCtx.ExecCfg.InternalExecutor.ExecEx(
			params.ctx,
			"delete-db-comment",
			params.p.Txn(),
			sessiondata.InternalExecutorOverride{User: security.RootUserName()},
			"DELETE FROM system.comments WHERE type=$1 AND object_id=$2 AND sub_id=0",
			keys.DatabaseCommentType,
			n.dbDesc.GetID())
		if err != nil {
			return err
		}
	}

	comment := ""
	if n.n.Comment != nil {
		comment = *n.n.Comment
	}
	return params.p.logEvent(params.ctx,
		n.dbDesc.GetID(),
		&eventpb.CommentOnDatabase{
			DatabaseName: n.n.Name.String(),
			Comment:      comment,
			NullComment:  n.n.Comment == nil,
		})
}

func (n *commentOnDatabaseNode) Next(runParams) (bool, error) { return false, nil }
func (n *commentOnDatabaseNode) Values() tree.Datums          { return tree.Datums{} }
func (n *commentOnDatabaseNode) Close(context.Context)        {}