this is the proposal i mentioned in the review

backend/v3/storage/database/database.go

@@ -2,8 +2,6 @@ package database
 
 import (
 	"context"
-
-	"github.com/jackc/pgx/v5"
 )
 
 // Pool is a connection pool. e.g. pgxpool
@@ -59,13 +57,25 @@ type Row interface {
 
 // Rows is an abstraction of sql.Rows.
 type Rows interface {
-	pgx.Rows
+	Scanner
+	Next() bool
+	Close() error
+	Err() error
 }
 
-// Collector is an interface for collecting rows into a specific type.
-type Collector[T any] interface {
-	// Collect collects a single row into the specified type.
-	Collect(Row) (T, error)
-	// CollectRows collects multiple rows into a slice of the specified type.
-	CollectRows(Rows) ([]T, error)
+type CollectableRows interface {
+	// Collect collects all rows and scans them into dest.
+	// dest must be a pointer to a slice of pointer to structs
+	// e.g. *[]*MyStruct
+	// Rows are closed after this call.
+	Collect(dest any) error
+	// CollectFirst collects the first row and scans it into dest.
+	// dest must be a pointer to a struct
+	// e.g. *MyStruct{}
+	// Rows are closed after this call.
+	CollectFirst(dest any) error
+	// CollectExactlyOneRow collects exactly one row and scans it into dest.
+	// e.g. *MyStruct{}
+	// Rows are closed after this call.
+	CollectExactlyOneRow(dest any) error
 }

backend/v3/storage/database/repository/instance.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"time"
 
-	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/zitadel/zitadel/backend/v3/domain"
 	"github.com/zitadel/zitadel/backend/v3/storage/database"
@@ -43,17 +42,11 @@ func (i *instance) Get(ctx context.Context, opts ...database.Condition) (*domain
 	andCondition := database.And(opts...)
 	i.writeCondition(&builder, andCondition)
 
-	rows, err := i.client.Query(ctx, builder.String(), builder.Args()...)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	return scanInstance(rows)
+	return scanInstance(ctx, i.client, &builder)
 }
 
 // List implements [domain.InstanceRepository].
-func (i *instance) List(ctx context.Context, opts ...database.Condition) ([]domain.Instance, error) {
+func (i *instance) List(ctx context.Context, opts ...database.Condition) ([]*domain.Instance, error) {
 	builder := database.StatementBuilder{}
 
 	builder.WriteString(queryInstanceStmt)
@@ -63,13 +56,7 @@ func (i *instance) List(ctx context.Context, opts ...database.Condition) ([]doma
 	andCondition := database.And(opts...)
 	i.writeCondition(&builder, andCondition)
 
-	rows, err := i.client.Query(ctx, builder.String(), builder.Args()...)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	return scanInstances(rows)
+	return scanInstances(ctx, i.client, &builder)
 }
 
 const createInstanceStmt = `INSERT INTO zitadel.instances (id, name, default_org_id, iam_project_id, console_client_id, console_app_id, default_language)` +
@@ -221,31 +208,29 @@ func (i *instance) writeCondition(
 	condition.Write(builder)
 }
 
-func scanInstance(rows database.Rows) (*domain.Instance, error) {
-	instance, err := pgx.CollectOneRow[domain.Instance](rows, pgx.RowToStructByNameLax[domain.Instance])
+func scanInstance(ctx context.Context, querier database.Querier, builder *database.StatementBuilder) (*domain.Instance, error) {
+	rows, err := querier.Query(ctx, builder.String(), builder.Args()...)
 	if err != nil {
-		// if no results returned, this is not a error
-		// it just means the instance was not found
-		// the caller should check if the returned instance is nil
-		if err.Error() == "no rows in result set" {
-			return nil, nil
-		}
 		return nil, err
 	}
 
-	return &instance, nil
+	instance := new(domain.Instance)
+	if err := rows.(database.CollectableRows).CollectExactlyOneRow(instance); err != nil {
+		return nil, err
+	}
+
+	return instance, nil
 }
 
-func scanInstances(rows database.Rows) ([]domain.Instance, error) {
-	instances, err := pgx.CollectRows[domain.Instance](rows, pgx.RowToStructByNameLax[domain.Instance])
+func scanInstances(ctx context.Context, querier database.Querier, builder *database.StatementBuilder) (instances []*domain.Instance, err error) {
+	rows, err := querier.Query(ctx, builder.String(), builder.Args()...)
 	if err != nil {
-		// if no results returned, this is not a error
-		// it just means the instance was not found
-		// the caller should check if the returned instance is nil
-		if err.Error() == "no rows in result set" {
-			return nil, nil
-		}
 		return nil, err
 	}
+
+	if err := rows.(database.CollectableRows).Collect(&instances); err != nil {
+		return nil, err
+	}
+
 	return instances, nil
 }

go.mod

@@ -119,6 +119,7 @@ require (
 	github.com/crewjam/httperr v0.2.0 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/envoyproxy/go-control-plane/envoy v1.32.4 // indirect
+	github.com/georgysavva/scany/v2 v2.1.4 // indirect
 	github.com/go-ini/ini v1.67.0 // indirect
 	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect

go.sum

@@ -233,6 +233,8 @@ github.com/fxamacker/cbor/v2 v2.7.0 h1:iM5WgngdRBanHcxugY4JySA0nk1wZorNOpTgCMedv
 github.com/fxamacker/cbor/v2 v2.7.0/go.mod h1:pxXPTn3joSm21Gbwsv0w9OSA2y1HFR9qXEeXQVeNoDQ=
 github.com/gabriel-vasile/mimetype v1.4.8 h1:FfZ3gj38NjllZIeJAmMhr+qKL8Wu+nOoI3GqacKw1NM=
 github.com/gabriel-vasile/mimetype v1.4.8/go.mod h1:ByKUIKGjh1ODkGM1asKUbQZOLGrPjydw3hYPU2YU9t8=
+github.com/georgysavva/scany/v2 v2.1.4 h1:nrzHEJ4oQVRoiKmocRqA1IyGOmM/GQOEsg9UjMR5Ip4=
+github.com/georgysavva/scany/v2 v2.1.4/go.mod h1:fqp9yHZzM/PFVa3/rYEC57VmDx+KDch0LoqrJzkvtos=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm+fLHvGI=
 github.com/gin-gonic/gin v1.6.3/go.mod h1:75u5sXoLsGZoRN5Sgbi1eraJ4GU3++wFwWzhwvtwp4M=
@@ -311,6 +313,7 @@ github.com/golang-jwt/jwt/v5 v5.2.2 h1:Rl4B7itRWVtYIHFrSNd7vhTiz9UpLdi6gZhZ3wEeD
 github.com/golang-jwt/jwt/v5 v5.2.2/go.mod h1:pqrtFR0X4osieyHYxtmOUWsAWrfe1Q5UVIyoH402zdk=
 github.com/golang-sql/civil v0.0.0-20190719163853-cb61b32ac6fe h1:lXe2qZdvpiX5WZkZR4hgp4KJVfY3nMkvmwbVkpv1rVY=
 github.com/golang-sql/civil v0.0.0-20190719163853-cb61b32ac6fe/go.mod h1:8vg3r2VgvsThLBIFL93Qb5yWzgyZWhEmBwUJWevAkK0=
+github.com/golang-sql/civil v0.0.0-20220223132316-b832511892a9 h1:au07oEsX2xN0ktxqI+Sida1w446QrXBRJ0nee3SNZlA=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
 github.com/golang/geo v0.0.0-20190916061304-5b978397cfec/go.mod h1:QZ0nwyI2jOfgRAoBvP+ab5aRr7c9x7lhGEJrKvBwjWI=
 github.com/golang/geo v0.0.0-20200319012246-673a6f80352d/go.mod h1:QZ0nwyI2jOfgRAoBvP+ab5aRr7c9x7lhGEJrKvBwjWI=