perf(fields): create index for instance domain query (#9146)

# Which Problems Are Solved

get instance by domain cannot provide an instance id because it is not
known at that time. This causes a full table scan on the fields table
because current indexes always include the `instance_id` column.

# How the Problems Are Solved

Added a specific index for this query.

# Additional Context

If a system has many fields and there is no cache hit for the given
domain this query can heaviuly influence database CPU usage, the newly
added resolves this problem.

cmd/setup/43.go

@@ -0,0 +1,40 @@
+package setup
+
+import (
+	"context"
+	"embed"
+	"fmt"
+
+	"github.com/zitadel/logging"
+
+	"github.com/zitadel/zitadel/internal/database"
+	"github.com/zitadel/zitadel/internal/eventstore"
+)
+
+var (
+	//go:embed 43/cockroach/*.sql
+	//go:embed 43/postgres/*.sql
+	createFieldsDomainIndex embed.FS
+)
+
+type CreateFieldsDomainIndex struct {
+	dbClient *database.DB
+}
+
+func (mig *CreateFieldsDomainIndex) Execute(ctx context.Context, _ eventstore.Event) error {
+	statements, err := readStatements(createFieldsDomainIndex, "43", mig.dbClient.Type())
+	if err != nil {
+		return err
+	}
+	for _, stmt := range statements {
+		logging.WithFields("file", stmt.file, "migration", mig.String()).Info("execute statement")
+		if _, err := mig.dbClient.ExecContext(ctx, stmt.query); err != nil {
+			return fmt.Errorf("%s %s: %w", mig.String(), stmt.file, err)
+		}
+	}
+	return nil
+}
+
+func (mig *CreateFieldsDomainIndex) String() string {
+	return "43_create_fields_domain_index"
+}

cmd/setup/43/cockroach/43.sql

@@ -0,0 +1,3 @@
+CREATE INDEX CONCURRENTLY IF NOT EXISTS fields_instance_domains_idx
+ON eventstore.fields (object_id)
+WHERE object_type = 'instance_domain' AND field_name = 'domain';

cmd/setup/43/postgres/43.sql

@@ -0,0 +1,3 @@
+CREATE INDEX CONCURRENTLY IF NOT EXISTS fields_instance_domains_idx
+ON eventstore.fields (object_id) INCLUDE (instance_id)
+WHERE object_type = 'instance_domain' AND field_name = 'domain';

cmd/setup/config.go

@@ -128,6 +128,7 @@ type Steps struct {
 	s38BackChannelLogoutNotificationStart   *BackChannelLogoutNotificationStart
 	s40InitPushFunc                         *InitPushFunc
 	s42Apps7OIDCConfigsLoginVersion         *Apps7OIDCConfigsLoginVersion
+	s43CreateFieldsDomainIndex              *CreateFieldsDomainIndex
 }
 
 func MustNewSteps(v *viper.Viper) *Steps {

cmd/setup/setup.go

@@ -171,6 +171,7 @@ func Setup(ctx context.Context, config *Config, steps *Steps, masterKey string)
 	steps.s38BackChannelLogoutNotificationStart = &BackChannelLogoutNotificationStart{dbClient: esPusherDBClient, esClient: eventstoreClient}
 	steps.s40InitPushFunc = &InitPushFunc{dbClient: esPusherDBClient}
 	steps.s42Apps7OIDCConfigsLoginVersion = &Apps7OIDCConfigsLoginVersion{dbClient: esPusherDBClient}
+	steps.s43CreateFieldsDomainIndex = &CreateFieldsDomainIndex{dbClient: queryDBClient}
 
 	err = projection.Create(ctx, projectionDBClient, eventstoreClient, config.Projections, nil, nil, nil)
 	logging.OnError(err).Fatal("unable to start projections")
@@ -242,6 +243,7 @@ func Setup(ctx context.Context, config *Config, steps *Steps, masterKey string)
 		steps.s33SMSConfigs3TwilioAddVerifyServiceSid,
 		steps.s37Apps7OIDConfigsBackChannelLogoutURI,
 		steps.s42Apps7OIDCConfigsLoginVersion,
+		steps.s43CreateFieldsDomainIndex,
 	} {
 		mustExecuteMigration(ctx, eventstoreClient, step, "migration failed")
 	}