fix(eventstore): use decimal for position (#9881)

Float64 which was used for the event.Position field is [not precise in
go and gets rounded](https://github.com/golang/go/issues/47300). This
can lead to unprecies position tracking of events and therefore
projections especially on cockcoachdb as the position used there is a
big number.

example of a unprecies position:
exact: 1725257931223002628
float64: 1725257931223002624.000000

The float64 was replaced by
[github.com/jackc/pgx-shopspring-decimal](https://github.com/jackc/pgx-shopspring-decimal).

Rename `latestSequence`-queries to `latestPosition`

closes https://github.com/zitadel/zitadel/issues/8863

internal/database/cockroach/crdb.go

@@ -73,10 +73,16 @@ func (_ *Config) Decode(configs []interface{}) (dialect.Connector, error) {
 }
 
 func (c *Config) Connect(useAdmin bool) (*sql.DB, *pgxpool.Pool, error) {
-	dialect.RegisterAfterConnect(func(ctx context.Context, c *pgx.Conn) error {
+	dialect.RegisterAfterConnect(func(ctx context.Context, conn *pgx.Conn) error {
 		// CockroachDB by default does not allow multiple modifications of the same table using ON CONFLICT
 		// This is needed to fill the fields table of the eventstore during eventstore.Push.
-		_, err := c.Exec(ctx, "SET enable_multiple_modifications_of_table = on")
+
+		// This modification is only needed on crdb so we check if the connection is crdb
+		// postgres doesn't have parameter so we check if the parameter is empty
+		if conn.PgConn().ParameterStatus("crdb_version") == "" {
+			return nil
+		}
+		_, err := conn.Exec(ctx, "SET enable_multiple_modifications_of_table = on")
 		return err
 	})
 	connConfig := dialect.NewConnectionConfig(c.MaxOpenConns, c.MaxIdleConns)

internal/database/dialect/connections.go

@@ -5,6 +5,8 @@ import (
 	"errors"
 	"reflect"
 
+	pgxdecimal "github.com/jackc/pgx-shopspring-decimal"
+
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
 )
@@ -21,7 +23,12 @@ type ConnectionConfig struct {
 	AfterConnect []func(ctx context.Context, c *pgx.Conn) error
 }
 
-var afterConnectFuncs []func(ctx context.Context, c *pgx.Conn) error
+var afterConnectFuncs = []func(ctx context.Context, c *pgx.Conn) error{
+	func(ctx context.Context, c *pgx.Conn) error {
+		pgxdecimal.Register(c.TypeMap())
+		return nil
+	},
+}
 
 func RegisterAfterConnect(f func(ctx context.Context, c *pgx.Conn) error) {
 	afterConnectFuncs = append(afterConnectFuncs, f)

internal/database/postgres/pg.go

@@ -81,13 +81,15 @@ func (c *Config) Connect(useAdmin bool) (*sql.DB, *pgxpool.Pool, error) {
 		return nil, nil, err
 	}
 
-	config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
-		for _, f := range connConfig.AfterConnect {
-			if err := f(ctx, conn); err != nil {
-				return err
+	if len(connConfig.AfterConnect) > 0 {
+		config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
+			for _, f := range connConfig.AfterConnect {
+				if err := f(ctx, conn); err != nil {
+					return err
+				}
 			}
+			return nil
 		}
-		return nil
 	}
 
 	if connConfig.MaxOpenConns != 0 {