fix(eventstore): prevent allocation of filtered events (#6749)

* fix(eventstore): prevent allocation of filtered events

Directly reduce each event obtained from a sql.Rows scan,
so that we do not have to allocate all events in a slice.

* reinstate the mutex as RWMutex

* scan data directly

* add todos

* fix(writemodels): add reduce of parent

* test: remove comment

* update comments

---------

Co-authored-by: adlerhurst <silvan.reusser@gmail.com>

internal/eventstore/search_query.go

@@ -1,9 +1,11 @@
 package eventstore
 
 import (
+	"context"
 	"database/sql"
 	"time"
 
+	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/errors"
 )
 
@@ -82,6 +84,13 @@ func (q SearchQueryBuilder) GetCreationDateAfter() time.Time {
 	return q.creationDateAfter
 }
 
+// ensureInstanceID makes sure that the instance id is always set
+func (b *SearchQueryBuilder) ensureInstanceID(ctx context.Context) {
+	if b.instanceID == nil && authz.GetInstance(ctx).InstanceID() != "" {
+		b.InstanceID(authz.GetInstance(ctx).InstanceID())
+	}
+}
+
 type SearchQuery struct {
 	builder        *SearchQueryBuilder
 	aggregateTypes []AggregateType