fix: optimize ennoblements query (#108)

Reviewed-on: twhelp/core#108

internal/bundb/ennoblement.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"sync"
 
 	"gitea.dwysokinski.me/twhelp/core/internal/bundb/internal/model"
 	"gitea.dwysokinski.me/twhelp/core/internal/domain"
@@ -56,19 +57,28 @@ func (e *Ennoblement) List(
 	var count int
 	var err error
 
-	q := e.db.NewSelect().
-		Model(&ennoblements).
-		Order("ennoblement.server_key ASC")
+	paramsApplier := listEnnoblementsParamsApplier{params}
 
-	q, err = listEnnoblementsParamsApplier{params}.apply(q)
+	base := e.db.NewSelect().
+		Model(&model.Ennoblement{}).
+		Order("ennoblement.server_key ASC").
+		Apply(paramsApplier.applyFilters).
+		Apply(paramsApplier.applyPagination)
+	base, err = paramsApplier.applySort(base)
 	if err != nil {
 		span.RecordError(err)
 		span.SetStatus(codes.Error, err.Error())
-		return nil, 0, fmt.Errorf("listEnnoblementsParamsApplier.apply: %w", err)
+		return nil, 0, fmt.Errorf("listEnnoblementsParamsApplier.applySort: %w", err)
 	}
 
+	q := e.db.NewSelect().
+		With("ennoblements_base", base).
+		Model(&ennoblements).
+		ModelTableExpr("ennoblements_base AS ennoblement").
+		Apply(paramsApplier.applyRelations)
+
 	if params.Count {
-		count, err = q.ScanAndCount(ctx)
+		count, err = e.listScanAndCount(ctx, base, q)
 	} else {
 		err = q.Scan(ctx)
 	}
@@ -86,25 +96,53 @@ func (e *Ennoblement) List(
 	return result, int64(count), nil
 }
 
+func (e *Ennoblement) listScanAndCount(
+	ctx context.Context,
+	base *bun.SelectQuery,
+	q *bun.SelectQuery,
+) (int, error) {
+	var wg sync.WaitGroup
+	var mu sync.Mutex
+	var count int
+	var err error
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		if scanErr := q.Scan(ctx); scanErr == nil {
+			mu.Lock()
+			if err == nil {
+				err = scanErr
+			}
+			mu.Unlock()
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		var countErr error
+		if count, countErr = base.Count(ctx); countErr != nil {
+			mu.Lock()
+			if err == nil {
+				err = countErr
+			}
+			mu.Unlock()
+		}
+	}()
+
+	wg.Wait()
+
+	return count, err
+}
+
 type listEnnoblementsParamsApplier struct {
 	params domain.ListEnnoblementsParams
 }
 
-func (l listEnnoblementsParamsApplier) apply(q *bun.SelectQuery) (*bun.SelectQuery, error) {
-	var err error
-
-	if l.params.ServerKeys != nil {
-		q = q.Where("ennoblement.server_key IN (?)", bun.In(l.params.ServerKeys))
-	}
-
-	if l.params.CreatedAtGTE.Valid {
-		q = q.Where("ennoblement.created_at >= ?", l.params.CreatedAtGTE.Time)
-	}
-
-	if l.params.CreatedAtLTE.Valid {
-		q = q.Where("ennoblement.created_at <= ?", l.params.CreatedAtLTE.Time)
-	}
-
+func (l listEnnoblementsParamsApplier) applyRelations(q *bun.SelectQuery) *bun.SelectQuery {
 	if l.params.IncludeVillage {
 		q = q.Relation("Village", func(q *bun.SelectQuery) *bun.SelectQuery {
 			return q.Column(villageMetaColumns...)
@@ -135,12 +173,23 @@ func (l listEnnoblementsParamsApplier) apply(q *bun.SelectQuery) (*bun.SelectQue
 		})
 	}
 
-	q, err = l.applySort(q)
-	if err != nil {
-		return nil, fmt.Errorf("listEnnoblementsParamsApplier.applySort: %w", err)
+	return q
+}
+
+func (l listEnnoblementsParamsApplier) applyFilters(q *bun.SelectQuery) *bun.SelectQuery {
+	if l.params.ServerKeys != nil {
+		q = q.Where("ennoblement.server_key IN (?)", bun.In(l.params.ServerKeys))
 	}
 
-	return l.applyPagination(q), nil
+	if l.params.CreatedAtGTE.Valid {
+		q = q.Where("ennoblement.created_at >= ?", l.params.CreatedAtGTE.Time)
+	}
+
+	if l.params.CreatedAtLTE.Valid {
+		q = q.Where("ennoblement.created_at <= ?", l.params.CreatedAtLTE.Time)
+	}
+
+	return q
 }
 
 func (l listEnnoblementsParamsApplier) applySort(q *bun.SelectQuery) (*bun.SelectQuery, error) {