feat(eventstore): increase parallel write capabilities (#5940)

This implementation increases parallel write capabilities of the eventstore.
Please have a look at the technical advisories: [05](https://zitadel.com/docs/support/advisory/a10005) and  [06](https://zitadel.com/docs/support/advisory/a10006).
The implementation of eventstore.push is rewritten and stored events are migrated to a new table `eventstore.events2`.
If you are using cockroach: make sure that the database user of ZITADEL has `VIEWACTIVITY` grant. This is used to query events.

internal/eventstore/v3/unique_constraints.go

@@ -0,0 +1,89 @@
+package eventstore
+
+import (
+	"context"
+	"database/sql"
+	_ "embed"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/jackc/pgconn"
+	"github.com/zitadel/logging"
+
+	errs "github.com/zitadel/zitadel/internal/errors"
+	"github.com/zitadel/zitadel/internal/eventstore"
+)
+
+var (
+	//go:embed unique_constraints_delete.sql
+	deleteConstraintStmt string
+	//go:embed unique_constraints_add.sql
+	addConstraintStmt string
+)
+
+func handleUniqueConstraints(ctx context.Context, tx *sql.Tx, commands []eventstore.Command) error {
+	deletePlaceholders := make([]string, 0)
+	deleteArgs := make([]any, 0)
+
+	addPlaceholders := make([]string, 0)
+	addArgs := make([]any, 0)
+	addConstraints := map[string]*eventstore.UniqueConstraint{}
+	deleteConstraints := map[string]*eventstore.UniqueConstraint{}
+
+	for _, command := range commands {
+		for _, constraint := range command.UniqueConstraints() {
+			switch constraint.Action {
+			case eventstore.UniqueConstraintAdd:
+				addPlaceholders = append(addPlaceholders, fmt.Sprintf("($%d, $%d, $%d)", len(addArgs)+1, len(addArgs)+2, len(addArgs)+3))
+				addArgs = append(addArgs, command.Aggregate().InstanceID, constraint.UniqueType, constraint.UniqueField)
+				addConstraints[fmt.Sprintf("('%s', '%s', '%s')", command.Aggregate().InstanceID, constraint.UniqueType, constraint.UniqueField)] = constraint
+			case eventstore.UniqueConstraintRemove:
+				deletePlaceholders = append(deletePlaceholders, fmt.Sprintf("(instance_id = $%d AND unique_type = $%d AND unique_field = $%d)", len(deleteArgs)+1, len(deleteArgs)+2, len(deleteArgs)+3))
+				deleteArgs = append(deleteArgs, command.Aggregate().InstanceID, constraint.UniqueType, constraint.UniqueField)
+				deleteConstraints[fmt.Sprintf("('%s', '%s', '%s')", command.Aggregate().InstanceID, constraint.UniqueType, constraint.UniqueField)] = constraint
+			case eventstore.UniqueConstraintInstanceRemove:
+				deletePlaceholders = append(deletePlaceholders, fmt.Sprintf("(instance_id = $%d)", len(deleteArgs)+1))
+				deleteArgs = append(deleteArgs, command.Aggregate().InstanceID)
+				deleteConstraints[fmt.Sprintf("('%s', '%s', '%s')", command.Aggregate().InstanceID, constraint.UniqueType, constraint.UniqueField)] = constraint
+			}
+		}
+	}
+
+	if len(deletePlaceholders) > 0 {
+		_, err := tx.ExecContext(ctx, fmt.Sprintf(deleteConstraintStmt, strings.Join(deletePlaceholders, " OR ")), deleteArgs...)
+		if err != nil {
+			logging.WithError(err).Warn("delete unique constraint failed")
+			errMessage := "Errors.Internal"
+			if constraint := constraintFromErr(err, deleteConstraints); constraint != nil {
+				errMessage = constraint.ErrorMessage
+			}
+			return errs.ThrowInternal(err, "V3-C8l3V", errMessage)
+		}
+	}
+	if len(addPlaceholders) > 0 {
+		_, err := tx.ExecContext(ctx, fmt.Sprintf(addConstraintStmt, strings.Join(addPlaceholders, ", ")), addArgs...)
+		if err != nil {
+			logging.WithError(err).Warn("add unique constraint failed")
+			errMessage := "Errors.Internal"
+			if constraint := constraintFromErr(err, addConstraints); constraint != nil {
+				errMessage = constraint.ErrorMessage
+			}
+			return errs.ThrowInternal(err, "V3-DKcYh", errMessage)
+		}
+	}
+	return nil
+}
+
+func constraintFromErr(err error, constraints map[string]*eventstore.UniqueConstraint) *eventstore.UniqueConstraint {
+	pgErr := new(pgconn.PgError)
+	if !errors.As(err, &pgErr) {
+		return nil
+	}
+	for key, constraint := range constraints {
+		if strings.Contains(pgErr.Detail, key) {
+			return constraint
+		}
+	}
+	return nil
+}