diff --git a/api_test.go b/api_test.go
index e80cd21..e726ed8 100644
--- a/api_test.go
+++ b/api_test.go
@@ -109,12 +109,9 @@ func setup(t *testing.T) *api.RestApi {
 		t.Fatal(err)
 	}
 
-	resolver := &graph.Resolver{DB: db}
-	if err := resolver.Init(); err != nil {
-		t.Fatal(err)
-	}
+	resolver := &graph.Resolver{DB: db, Repo: &repository.JobRepository{DB: db}}
 	return &api.RestApi{
-		JobRepository: &repository.JobRepository{DB: db},
+		JobRepository: resolver.Repo,
 		Resolver:      resolver,
 	}
 }
diff --git a/graph/resolver.go b/graph/resolver.go
index a023b5b..ce08e33 100644
--- a/graph/resolver.go
+++ b/graph/resolver.go
@@ -1,17 +1,7 @@
 package graph
 
 import (
-	"context"
-	"errors"
-	"fmt"
-	"regexp"
-	"strings"
-
-	"github.com/ClusterCockpit/cc-backend/auth"
-	"github.com/ClusterCockpit/cc-backend/graph/model"
-	"github.com/ClusterCockpit/cc-backend/log"
-	"github.com/ClusterCockpit/cc-backend/schema"
-	sq "github.com/Masterminds/squirrel"
+	"github.com/ClusterCockpit/cc-backend/repository"
 	"github.com/jmoiron/sqlx"
 )
 
@@ -20,215 +10,6 @@ import (
 // It serves as dependency injection for your app, add any dependencies you require here.
 
 type Resolver struct {
-	DB *sqlx.DB
-
-	findJobByIdStmt         *sqlx.Stmt
-	findJobByIdWithUserStmt *sqlx.Stmt
-}
-
-func (r *Resolver) Init() error {
-	findJobById, _, err := sq.Select(schema.JobColumns...).From("job").Where("job.id = ?", nil).ToSql()
-	if err != nil {
-		return err
-	}
-
-	r.findJobByIdStmt, err = r.DB.Preparex(findJobById)
-	if err != nil {
-		return err
-	}
-
-	findJobByIdWithUser, _, err := sq.Select(schema.JobColumns...).From("job").Where("job.id = ?", nil).Where("job.user = ?").ToSql()
-	if err != nil {
-		return err
-	}
-
-	r.findJobByIdWithUserStmt, err = r.DB.Preparex(findJobByIdWithUser)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// Helper function for the `jobs` GraphQL-Query. Is also used elsewhere when a list of jobs is needed.
-func (r *Resolver) queryJobs(
-	ctx context.Context,
-	filters []*model.JobFilter,
-	page *model.PageRequest,
-	order *model.OrderByInput) ([]*schema.Job, int, error) {
-
-	query := sq.Select(schema.JobColumns...).From("job")
-	query = securityCheck(ctx, query)
-
-	if order != nil {
-		field := toSnakeCase(order.Field)
-		if order.Order == model.SortDirectionEnumAsc {
-			query = query.OrderBy(fmt.Sprintf("job.%s ASC", field))
-		} else if order.Order == model.SortDirectionEnumDesc {
-			query = query.OrderBy(fmt.Sprintf("job.%s DESC", field))
-		} else {
-			return nil, 0, errors.New("invalid sorting order")
-		}
-	}
-
-	if page != nil {
-		limit := uint64(page.ItemsPerPage)
-		query = query.Offset((uint64(page.Page) - 1) * limit).Limit(limit)
-	} else {
-		query = query.Limit(50)
-	}
-
-	for _, f := range filters {
-		query = buildWhereClause(f, query)
-	}
-
-	sql, args, err := query.ToSql()
-	if err != nil {
-		return nil, 0, err
-	}
-
-	log.Debugf("SQL query: `%s`, args: %#v", sql, args)
-	rows, err := r.DB.Queryx(sql, args...)
-	if err != nil {
-		return nil, 0, err
-	}
-
-	jobs := make([]*schema.Job, 0, 50)
-	for rows.Next() {
-		job, err := schema.ScanJob(rows)
-		if err != nil {
-			return nil, 0, err
-		}
-		jobs = append(jobs, job)
-	}
-
-	// count all jobs:
-	query = sq.Select("count(*)").From("job")
-	for _, f := range filters {
-		query = buildWhereClause(f, query)
-	}
-	query = securityCheck(ctx, query)
-	var count int
-	if err := query.RunWith(r.DB).Scan(&count); err != nil {
-		return nil, 0, err
-	}
-
-	return jobs, count, nil
-}
-
-func securityCheck(ctx context.Context, query sq.SelectBuilder) sq.SelectBuilder {
-	user := auth.GetUser(ctx)
-	if user == nil || user.HasRole(auth.RoleAdmin) {
-		return query
-	}
-
-	return query.Where("job.user = ?", user.Username)
-}
-
-// Build a sq.SelectBuilder out of a schema.JobFilter.
-func buildWhereClause(filter *model.JobFilter, query sq.SelectBuilder) sq.SelectBuilder {
-	if filter.Tags != nil {
-		query = query.Join("jobtag ON jobtag.job_id = job.id").Where(sq.Eq{"jobtag.tag_id": filter.Tags})
-	}
-	if filter.JobID != nil {
-		query = buildStringCondition("job.job_id", filter.JobID, query)
-	}
-	if filter.ArrayJobID != nil {
-		query = query.Where("job.array_job_id = ?", *filter.ArrayJobID)
-	}
-	if filter.User != nil {
-		query = buildStringCondition("job.user", filter.User, query)
-	}
-	if filter.Project != nil {
-		query = buildStringCondition("job.project", filter.Project, query)
-	}
-	if filter.Cluster != nil {
-		query = buildStringCondition("job.cluster", filter.Cluster, query)
-	}
-	if filter.Partition != nil {
-		query = buildStringCondition("job.partition", filter.Partition, query)
-	}
-	if filter.StartTime != nil {
-		query = buildTimeCondition("job.start_time", filter.StartTime, query)
-	}
-	if filter.Duration != nil {
-		query = buildIntCondition("job.duration", filter.Duration, query)
-	}
-	if filter.State != nil {
-		states := make([]string, len(filter.State))
-		for i, val := range filter.State {
-			states[i] = string(val)
-		}
-
-		query = query.Where(sq.Eq{"job.job_state": states})
-	}
-	if filter.NumNodes != nil {
-		query = buildIntCondition("job.num_nodes", filter.NumNodes, query)
-	}
-	if filter.NumAccelerators != nil {
-		query = buildIntCondition("job.num_acc", filter.NumAccelerators, query)
-	}
-	if filter.NumHWThreads != nil {
-		query = buildIntCondition("job.num_hwthreads", filter.NumHWThreads, query)
-	}
-	if filter.FlopsAnyAvg != nil {
-		query = buildFloatCondition("job.flops_any_avg", filter.FlopsAnyAvg, query)
-	}
-	if filter.MemBwAvg != nil {
-		query = buildFloatCondition("job.mem_bw_avg", filter.MemBwAvg, query)
-	}
-	if filter.LoadAvg != nil {
-		query = buildFloatCondition("job.load_avg", filter.LoadAvg, query)
-	}
-	if filter.MemUsedMax != nil {
-		query = buildFloatCondition("job.mem_used_max", filter.MemUsedMax, query)
-	}
-	return query
-}
-
-func buildIntCondition(field string, cond *model.IntRange, query sq.SelectBuilder) sq.SelectBuilder {
-	return query.Where(field+" BETWEEN ? AND ?", cond.From, cond.To)
-}
-
-func buildTimeCondition(field string, cond *model.TimeRange, query sq.SelectBuilder) sq.SelectBuilder {
-	if cond.From != nil && cond.To != nil {
-		return query.Where(field+" BETWEEN ? AND ?", cond.From.Unix(), cond.To.Unix())
-	} else if cond.From != nil {
-		return query.Where("? <= "+field, cond.From.Unix())
-	} else if cond.To != nil {
-		return query.Where(field+" <= ?", cond.To.Unix())
-	} else {
-		return query
-	}
-}
-
-func buildFloatCondition(field string, cond *model.FloatRange, query sq.SelectBuilder) sq.SelectBuilder {
-	return query.Where(field+" BETWEEN ? AND ?", cond.From, cond.To)
-}
-
-func buildStringCondition(field string, cond *model.StringInput, query sq.SelectBuilder) sq.SelectBuilder {
-	if cond.Eq != nil {
-		return query.Where(field+" = ?", *cond.Eq)
-	}
-	if cond.StartsWith != nil {
-		return query.Where(field+" LIKE ?", fmt.Sprint(*cond.StartsWith, "%"))
-	}
-	if cond.EndsWith != nil {
-		return query.Where(field+" LIKE ?", fmt.Sprint("%", *cond.EndsWith))
-	}
-	if cond.Contains != nil {
-		return query.Where(field+" LIKE ?", fmt.Sprint("%", *cond.Contains, "%"))
-	}
-	return query
-}
-
-var matchFirstCap = regexp.MustCompile("(.)([A-Z][a-z]+)")
-var matchAllCap = regexp.MustCompile("([a-z0-9])([A-Z])")
-
-func toSnakeCase(str string) string {
-	str = strings.ReplaceAll(str, "'", "")
-	str = strings.ReplaceAll(str, "\\", "")
-	snake := matchFirstCap.ReplaceAllString(str, "${1}_${2}")
-	snake = matchAllCap.ReplaceAllString(snake, "${1}_${2}")
-	return strings.ToLower(snake)
+	DB   *sqlx.DB
+	Repo *repository.JobRepository
 }
diff --git a/graph/schema.resolvers.go b/graph/schema.resolvers.go
index bfe0542..bd5c5f9 100644
--- a/graph/schema.resolvers.go
+++ b/graph/schema.resolvers.go
@@ -40,12 +40,7 @@ func (r *jobResolver) Tags(ctx context.Context, obj *schema.Job) ([]*schema.Tag,
 }
 
 func (r *mutationResolver) CreateTag(ctx context.Context, typeArg string, name string) (*schema.Tag, error) {
-	res, err := r.DB.Exec("INSERT INTO tag (tag_type, tag_name) VALUES ($1, $2)", typeArg, name)
-	if err != nil {
-		return nil, err
-	}
-
-	id, err := res.LastInsertId()
+	id, err := r.Repo.CreateTag(typeArg, name)
 	if err != nil {
 		return nil, err
 	}
@@ -59,18 +54,18 @@ func (r *mutationResolver) DeleteTag(ctx context.Context, id string) (string, er
 }
 
 func (r *mutationResolver) AddTagsToJob(ctx context.Context, job string, tagIds []string) ([]*schema.Tag, error) {
-	jid, err := strconv.Atoi(job)
+	jid, err := strconv.ParseInt(job, 10, 64)
 	if err != nil {
 		return nil, err
 	}
 
 	for _, tagId := range tagIds {
-		tid, err := strconv.Atoi(tagId)
+		tid, err := strconv.ParseInt(tagId, 10, 64)
 		if err != nil {
 			return nil, err
 		}
 
-		if _, err := r.DB.Exec("INSERT INTO jobtag (job_id, tag_id) VALUES ($1, $2)", jid, tid); err != nil {
+		if err := r.Repo.AddTag(jid, tid); err != nil {
 			return nil, err
 		}
 	}
@@ -148,14 +143,21 @@ func (r *queryResolver) Tags(ctx context.Context) ([]*schema.Tag, error) {
 }
 
 func (r *queryResolver) Job(ctx context.Context, id string) (*schema.Job, error) {
-	// This query is very common (mostly called through other resolvers such as JobMetrics),
-	// so we use prepared statements here.
-	user := auth.GetUser(ctx)
-	if user == nil || user.HasRole(auth.RoleAdmin) {
-		return schema.ScanJob(r.findJobByIdStmt.QueryRowx(id))
+	numericId, err := strconv.ParseInt(id, 10, 64)
+	if err != nil {
+		return nil, err
 	}
 
-	return schema.ScanJob(r.findJobByIdWithUserStmt.QueryRowx(id, user.Username))
+	job, err := r.Repo.FindById(numericId)
+	if err != nil {
+		return nil, err
+	}
+
+	if user := auth.GetUser(ctx); user != nil && !user.HasRole(auth.RoleAdmin) && job.User != user.Username {
+		return nil, errors.New("you are not allowed to see this job")
+	}
+
+	return job, nil
 }
 
 func (r *queryResolver) JobMetrics(ctx context.Context, id string, metrics []string, scopes []schema.MetricScope) ([]*model.JobMetricWithName, error) {
@@ -191,7 +193,12 @@ func (r *queryResolver) JobsFootprints(ctx context.Context, filter []*model.JobF
 }
 
 func (r *queryResolver) Jobs(ctx context.Context, filter []*model.JobFilter, page *model.PageRequest, order *model.OrderByInput) (*model.JobResultList, error) {
-	jobs, count, err := r.queryJobs(ctx, filter, page, order)
+	jobs, err := r.Repo.QueryJobs(ctx, filter, page, order)
+	if err != nil {
+		return nil, err
+	}
+
+	count, err := r.Repo.CountJobs(ctx, filter)
 	if err != nil {
 		return nil, err
 	}
diff --git a/graph/stats.go b/graph/stats.go
index d979229..bca0afe 100644
--- a/graph/stats.go
+++ b/graph/stats.go
@@ -11,6 +11,7 @@ import (
 	"github.com/ClusterCockpit/cc-backend/config"
 	"github.com/ClusterCockpit/cc-backend/graph/model"
 	"github.com/ClusterCockpit/cc-backend/metricdata"
+	"github.com/ClusterCockpit/cc-backend/repository"
 	"github.com/ClusterCockpit/cc-backend/schema"
 	sq "github.com/Masterminds/squirrel"
 )
@@ -53,9 +54,9 @@ func (r *queryResolver) jobsStatistics(ctx context.Context, filter []*model.JobF
 				Where("job.cluster = ?", cluster.Name).
 				Where("job.partition = ?", partition.Name)
 
-			query = securityCheck(ctx, query)
+			query = repository.SecurityCheck(ctx, query)
 			for _, f := range filter {
-				query = buildWhereClause(f, query)
+				query = repository.BuildWhereClause(f, query)
 			}
 
 			rows, err := query.RunWith(r.DB).Query()
@@ -90,9 +91,9 @@ func (r *queryResolver) jobsStatistics(ctx context.Context, filter []*model.JobF
 
 	if groupBy == nil {
 		query := sq.Select("COUNT(job.id)").From("job").Where("job.duration < 120")
-		query = securityCheck(ctx, query)
+		query = repository.SecurityCheck(ctx, query)
 		for _, f := range filter {
-			query = buildWhereClause(f, query)
+			query = repository.BuildWhereClause(f, query)
 		}
 		if err := query.RunWith(r.DB).QueryRow().Scan(&(stats[""].ShortJobs)); err != nil {
 			return nil, err
@@ -100,9 +101,9 @@ func (r *queryResolver) jobsStatistics(ctx context.Context, filter []*model.JobF
 	} else {
 		col := groupBy2column[*groupBy]
 		query := sq.Select(col, "COUNT(job.id)").From("job").Where("job.duration < 120")
-		query = securityCheck(ctx, query)
+		query = repository.SecurityCheck(ctx, query)
 		for _, f := range filter {
-			query = buildWhereClause(f, query)
+			query = repository.BuildWhereClause(f, query)
 		}
 		rows, err := query.RunWith(r.DB).Query()
 		if err != nil {
@@ -162,9 +163,9 @@ func (r *queryResolver) jobsStatistics(ctx context.Context, filter []*model.JobF
 // to add a condition to the query of the kind "<col> = <id>".
 func (r *queryResolver) jobsStatisticsHistogram(ctx context.Context, value string, filters []*model.JobFilter, id, col string) ([]*model.HistoPoint, error) {
 	query := sq.Select(value, "COUNT(job.id) AS count").From("job")
-	query = securityCheck(ctx, query)
+	query = repository.SecurityCheck(ctx, query)
 	for _, f := range filters {
-		query = buildWhereClause(f, query)
+		query = repository.BuildWhereClause(f, query)
 	}
 
 	if len(id) != 0 && len(col) != 0 {
@@ -188,14 +189,16 @@ func (r *queryResolver) jobsStatisticsHistogram(ctx context.Context, value strin
 	return points, nil
 }
 
+const MAX_JOBS_FOR_ANALYSIS = 500
+
 // Helper function for the rooflineHeatmap GraphQL query placed here so that schema.resolvers.go is not too full.
 func (r *Resolver) rooflineHeatmap(ctx context.Context, filter []*model.JobFilter, rows int, cols int, minX float64, minY float64, maxX float64, maxY float64) ([][]float64, error) {
-	jobs, count, err := r.queryJobs(ctx, filter, &model.PageRequest{Page: 1, ItemsPerPage: 501}, nil)
+	jobs, err := r.Repo.QueryJobs(ctx, filter, &model.PageRequest{Page: 1, ItemsPerPage: MAX_JOBS_FOR_ANALYSIS + 1}, nil)
 	if err != nil {
 		return nil, err
 	}
-	if len(jobs) > 500 {
-		return nil, fmt.Errorf("too many jobs matched (matched: %d, max: %d)", count, 500)
+	if len(jobs) > MAX_JOBS_FOR_ANALYSIS {
+		return nil, fmt.Errorf("too many jobs matched (max: %d)", MAX_JOBS_FOR_ANALYSIS)
 	}
 
 	fcols, frows := float64(cols), float64(rows)
@@ -250,12 +253,12 @@ func (r *Resolver) rooflineHeatmap(ctx context.Context, filter []*model.JobFilte
 
 // Helper function for the jobsFootprints GraphQL query placed here so that schema.resolvers.go is not too full.
 func (r *queryResolver) jobsFootprints(ctx context.Context, filter []*model.JobFilter, metrics []string) ([]*model.MetricFootprints, error) {
-	jobs, count, err := r.queryJobs(ctx, filter, &model.PageRequest{Page: 1, ItemsPerPage: 501}, nil)
+	jobs, err := r.Repo.QueryJobs(ctx, filter, &model.PageRequest{Page: 1, ItemsPerPage: MAX_JOBS_FOR_ANALYSIS + 1}, nil)
 	if err != nil {
 		return nil, err
 	}
-	if len(jobs) > 500 {
-		return nil, fmt.Errorf("too many jobs matched (matched: %d, max: %d)", count, 500)
+	if len(jobs) > MAX_JOBS_FOR_ANALYSIS {
+		return nil, fmt.Errorf("too many jobs matched (max: %d)", MAX_JOBS_FOR_ANALYSIS)
 	}
 
 	avgs := make([][]schema.Float, len(metrics))
diff --git a/repository/job.go b/repository/job.go
index 9d01051..770074f 100644
--- a/repository/job.go
+++ b/repository/job.go
@@ -4,7 +4,6 @@ import (
 	"context"
 	"database/sql"
 	"errors"
-	"fmt"
 	"strconv"
 
 	"github.com/ClusterCockpit/cc-backend/auth"
@@ -42,8 +41,7 @@ func (r *JobRepository) Find(
 		return nil, err
 	}
 
-	job, err := schema.ScanJob(r.DB.QueryRowx(sqlQuery, args...))
-	return job, err
+	return schema.ScanJob(r.DB.QueryRowx(sqlQuery, args...))
 }
 
 // FindById executes a SQL query to find a specific batch job.
@@ -58,8 +56,7 @@ func (r *JobRepository) FindById(
 		return nil, err
 	}
 
-	job, err := schema.ScanJob(r.DB.QueryRowx(sqlQuery, args...))
-	return job, err
+	return schema.ScanJob(r.DB.QueryRowx(sqlQuery, args...))
 }
 
 // Start inserts a new job in the table, returning the unique job ID.
@@ -96,20 +93,9 @@ func (r *JobRepository) Stop(
 	return
 }
 
-// CountJobs returns the number of jobs for the specified user (if a non-admin user is found in that context) and state.
+// CountJobsPerCluster returns the number of jobs for the specified user (if a non-admin user is found in that context) and state.
 // The counts are grouped by cluster.
-func (r *JobRepository) CountJobs(ctx context.Context, state *schema.JobState) (map[string]int, error) {
-	// q := sq.Select("count(*)").From("job")
-	// if cluster != nil {
-	// 	q = q.Where("job.cluster = ?", cluster)
-	// }
-	// if state != nil {
-	// 	q = q.Where("job.job_state = ?", string(*state))
-	// }
-
-	// err = q.RunWith(r.DB).QueryRow().Scan(&count)
-	// return
-
+func (r *JobRepository) CountJobsPerCluster(ctx context.Context, state *schema.JobState) (map[string]int, error) {
 	q := sq.Select("job.cluster, count(*)").From("job").GroupBy("job.cluster")
 	if state != nil {
 		q = q.Where("job.job_state = ?", string(*state))
@@ -137,13 +123,6 @@ func (r *JobRepository) CountJobs(ctx context.Context, state *schema.JobState) (
 	return counts, nil
 }
 
-// func (r *JobRepository) Query(
-// 	filters []*model.JobFilter,
-// 	page *model.PageRequest,
-// 	order *model.OrderByInput) ([]*schema.Job, int, error) {
-
-// }
-
 func (r *JobRepository) UpdateMonitoringStatus(job int64, monitoringStatus int32) (err error) {
 	stmt := sq.Update("job").
 		Set("monitoring_status", monitoringStatus).
@@ -186,91 +165,6 @@ func (r *JobRepository) Archive(
 	return nil
 }
 
-// Add the tag with id `tagId` to the job with the database id `jobId`.
-func (r *JobRepository) AddTag(jobId int64, tagId int64) error {
-	_, err := r.DB.Exec(`INSERT INTO jobtag (job_id, tag_id) VALUES (?, ?)`, jobId, tagId)
-	return err
-}
-
-// CreateTag creates a new tag with the specified type and name and returns its database id.
-func (r *JobRepository) CreateTag(tagType string, tagName string) (tagId int64, err error) {
-	res, err := r.DB.Exec("INSERT INTO tag (tag_type, tag_name) VALUES ($1, $2)", tagType, tagName)
-	if err != nil {
-		return 0, err
-	}
-
-	return res.LastInsertId()
-}
-
-func (r *JobRepository) GetTags(user *string) (tags []schema.Tag, counts map[string]int, err error) {
-	tags = make([]schema.Tag, 0, 100)
-	xrows, err := r.DB.Queryx("SELECT * FROM tag")
-	if err != nil {
-		return nil, nil, err
-	}
-
-	for xrows.Next() {
-		var t schema.Tag
-		if err := xrows.StructScan(&t); err != nil {
-			return nil, nil, err
-		}
-		tags = append(tags, t)
-	}
-
-	q := sq.Select("t.tag_name, count(jt.tag_id)").
-		From("tag t").
-		LeftJoin("jobtag jt ON t.id = jt.tag_id").
-		GroupBy("t.tag_name")
-	if user != nil {
-		q = q.Where("jt.job_id IN (SELECT id FROM job WHERE job.user = ?)", *user)
-	}
-
-	rows, err := q.RunWith(r.DB).Query()
-	if err != nil {
-		return nil, nil, err
-	}
-
-	counts = make(map[string]int)
-
-	for rows.Next() {
-		var tagName string
-		var count int
-		err = rows.Scan(&tagName, &count)
-		if err != nil {
-			fmt.Println(err)
-		}
-		counts[tagName] = count
-	}
-	err = rows.Err()
-
-	return
-}
-
-// AddTagOrCreate adds the tag with the specified type and name to the job with the database id `jobId`.
-// If such a tag does not yet exist, it is created.
-func (r *JobRepository) AddTagOrCreate(jobId int64, tagType string, tagName string) (tagId int64, err error) {
-	tagId, exists := r.TagId(tagType, tagName)
-	if !exists {
-		tagId, err = r.CreateTag(tagType, tagName)
-		if err != nil {
-			return 0, err
-		}
-	}
-
-	return tagId, r.AddTag(jobId, tagId)
-}
-
-// TagId returns the database id of the tag with the specified type and name.
-func (r *JobRepository) TagId(tagType string, tagName string) (tagId int64, exists bool) {
-	exists = true
-	if err := sq.Select("id").From("tag").
-		Where("tag.tag_type = ?", tagType).Where("tag.tag_name = ?", tagName).
-		RunWith(r.DB).QueryRow().Scan(&tagId); err != nil {
-		exists = false
-	}
-	return
-}
-
 var ErrNotFound = errors.New("no such job or user")
 
 // FindJobOrUser returns a job database ID or a username if a job or user machtes the search term.
diff --git a/repository/job_test.go b/repository/job_test.go
index 8a43617..2c8e75f 100644
--- a/repository/job_test.go
+++ b/repository/job_test.go
@@ -7,8 +7,6 @@ import (
 	"github.com/jmoiron/sqlx"
 
 	"github.com/ClusterCockpit/cc-backend/test"
-	_ "github.com/go-sql-driver/mysql"
-	_ "github.com/mattn/go-sqlite3"
 )
 
 var db *sqlx.DB
@@ -57,7 +55,7 @@ func TestFindById(t *testing.T) {
 func TestGetTags(t *testing.T) {
 	r := setup(t)
 
-	tags, counts, err := r.GetTags(nil)
+	tags, counts, err := r.CountTags(nil)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/repository/query.go b/repository/query.go
new file mode 100644
index 0000000..53a863e
--- /dev/null
+++ b/repository/query.go
@@ -0,0 +1,212 @@
+package repository
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/ClusterCockpit/cc-backend/auth"
+	"github.com/ClusterCockpit/cc-backend/graph/model"
+	"github.com/ClusterCockpit/cc-backend/log"
+	"github.com/ClusterCockpit/cc-backend/schema"
+	sq "github.com/Masterminds/squirrel"
+)
+
+// QueryJobs returns a list of jobs matching the provided filters. page and order are optional-
+func (r *JobRepository) QueryJobs(
+	ctx context.Context,
+	filters []*model.JobFilter,
+	page *model.PageRequest,
+	order *model.OrderByInput) ([]*schema.Job, error) {
+
+	query := sq.Select(schema.JobColumns...).From("job")
+	query = SecurityCheck(ctx, query)
+
+	if order != nil {
+		field := toSnakeCase(order.Field)
+		if order.Order == model.SortDirectionEnumAsc {
+			query = query.OrderBy(fmt.Sprintf("job.%s ASC", field))
+		} else if order.Order == model.SortDirectionEnumDesc {
+			query = query.OrderBy(fmt.Sprintf("job.%s DESC", field))
+		} else {
+			return nil, errors.New("invalid sorting order")
+		}
+	}
+
+	if page != nil {
+		limit := uint64(page.ItemsPerPage)
+		query = query.Offset((uint64(page.Page) - 1) * limit).Limit(limit)
+	} else {
+		query = query.Limit(50)
+	}
+
+	for _, f := range filters {
+		query = BuildWhereClause(f, query)
+	}
+
+	sql, args, err := query.ToSql()
+	if err != nil {
+		return nil, err
+	}
+
+	log.Debugf("SQL query: `%s`, args: %#v", sql, args)
+	rows, err := r.DB.Queryx(sql, args...)
+	if err != nil {
+		return nil, err
+	}
+
+	jobs := make([]*schema.Job, 0, 50)
+	for rows.Next() {
+		job, err := schema.ScanJob(rows)
+		if err != nil {
+			return nil, err
+		}
+		jobs = append(jobs, job)
+	}
+
+	return jobs, nil
+}
+
+// CountJobs counts the number of jobs matching the filters.
+func (r *JobRepository) CountJobs(
+	ctx context.Context,
+	filters []*model.JobFilter) (int, error) {
+
+	// count all jobs:
+	query := sq.Select("count(*)").From("job")
+	query = SecurityCheck(ctx, query)
+	for _, f := range filters {
+		query = BuildWhereClause(f, query)
+	}
+	var count int
+	if err := query.RunWith(r.DB).Scan(&count); err != nil {
+		return 0, err
+	}
+
+	return count, nil
+}
+
+func SecurityCheck(ctx context.Context, query sq.SelectBuilder) sq.SelectBuilder {
+	user := auth.GetUser(ctx)
+	if user == nil || user.HasRole(auth.RoleAdmin) {
+		return query
+	}
+
+	return query.Where("job.user = ?", user.Username)
+}
+
+// Build a sq.SelectBuilder out of a schema.JobFilter.
+func BuildWhereClause(filter *model.JobFilter, query sq.SelectBuilder) sq.SelectBuilder {
+	if filter.Tags != nil {
+		query = query.Join("jobtag ON jobtag.job_id = job.id").Where(sq.Eq{"jobtag.tag_id": filter.Tags})
+	}
+	if filter.JobID != nil {
+		query = buildStringCondition("job.job_id", filter.JobID, query)
+	}
+	if filter.ArrayJobID != nil {
+		query = query.Where("job.array_job_id = ?", *filter.ArrayJobID)
+	}
+	if filter.User != nil {
+		query = buildStringCondition("job.user", filter.User, query)
+	}
+	if filter.Project != nil {
+		query = buildStringCondition("job.project", filter.Project, query)
+	}
+	if filter.Cluster != nil {
+		query = buildStringCondition("job.cluster", filter.Cluster, query)
+	}
+	if filter.Partition != nil {
+		query = buildStringCondition("job.partition", filter.Partition, query)
+	}
+	if filter.StartTime != nil {
+		query = buildTimeCondition("job.start_time", filter.StartTime, query)
+	}
+	if filter.Duration != nil {
+		query = buildIntCondition("job.duration", filter.Duration, query)
+	}
+	if filter.State != nil {
+		states := make([]string, len(filter.State))
+		for i, val := range filter.State {
+			states[i] = string(val)
+		}
+
+		query = query.Where(sq.Eq{"job.job_state": states})
+	}
+	if filter.NumNodes != nil {
+		query = buildIntCondition("job.num_nodes", filter.NumNodes, query)
+	}
+	if filter.NumAccelerators != nil {
+		query = buildIntCondition("job.num_acc", filter.NumAccelerators, query)
+	}
+	if filter.NumHWThreads != nil {
+		query = buildIntCondition("job.num_hwthreads", filter.NumHWThreads, query)
+	}
+	if filter.FlopsAnyAvg != nil {
+		query = buildFloatCondition("job.flops_any_avg", filter.FlopsAnyAvg, query)
+	}
+	if filter.MemBwAvg != nil {
+		query = buildFloatCondition("job.mem_bw_avg", filter.MemBwAvg, query)
+	}
+	if filter.LoadAvg != nil {
+		query = buildFloatCondition("job.load_avg", filter.LoadAvg, query)
+	}
+	if filter.MemUsedMax != nil {
+		query = buildFloatCondition("job.mem_used_max", filter.MemUsedMax, query)
+	}
+	return query
+}
+
+func buildIntCondition(field string, cond *model.IntRange, query sq.SelectBuilder) sq.SelectBuilder {
+	return query.Where(field+" BETWEEN ? AND ?", cond.From, cond.To)
+}
+
+func buildTimeCondition(field string, cond *model.TimeRange, query sq.SelectBuilder) sq.SelectBuilder {
+	if cond.From != nil && cond.To != nil {
+		return query.Where(field+" BETWEEN ? AND ?", cond.From.Unix(), cond.To.Unix())
+	} else if cond.From != nil {
+		return query.Where("? <= "+field, cond.From.Unix())
+	} else if cond.To != nil {
+		return query.Where(field+" <= ?", cond.To.Unix())
+	} else {
+		return query
+	}
+}
+
+func buildFloatCondition(field string, cond *model.FloatRange, query sq.SelectBuilder) sq.SelectBuilder {
+	return query.Where(field+" BETWEEN ? AND ?", cond.From, cond.To)
+}
+
+func buildStringCondition(field string, cond *model.StringInput, query sq.SelectBuilder) sq.SelectBuilder {
+	if cond.Eq != nil {
+		return query.Where(field+" = ?", *cond.Eq)
+	}
+	if cond.StartsWith != nil {
+		return query.Where(field+" LIKE ?", fmt.Sprint(*cond.StartsWith, "%"))
+	}
+	if cond.EndsWith != nil {
+		return query.Where(field+" LIKE ?", fmt.Sprint("%", *cond.EndsWith))
+	}
+	if cond.Contains != nil {
+		return query.Where(field+" LIKE ?", fmt.Sprint("%", *cond.Contains, "%"))
+	}
+	return query
+}
+
+var matchFirstCap = regexp.MustCompile("(.)([A-Z][a-z]+)")
+var matchAllCap = regexp.MustCompile("([a-z0-9])([A-Z])")
+
+func toSnakeCase(str string) string {
+	for _, c := range str {
+		if c == '\'' || c == '\\' {
+			panic("A hacker (probably not)!!!")
+		}
+	}
+
+	str = strings.ReplaceAll(str, "'", "")
+	str = strings.ReplaceAll(str, "\\", "")
+	snake := matchFirstCap.ReplaceAllString(str, "${1}_${2}")
+	snake = matchAllCap.ReplaceAllString(snake, "${1}_${2}")
+	return strings.ToLower(snake)
+}
diff --git a/repository/tags.go b/repository/tags.go
new file mode 100644
index 0000000..c8d8310
--- /dev/null
+++ b/repository/tags.go
@@ -0,0 +1,93 @@
+package repository
+
+import (
+	"fmt"
+
+	"github.com/ClusterCockpit/cc-backend/schema"
+	sq "github.com/Masterminds/squirrel"
+)
+
+// Add the tag with id `tagId` to the job with the database id `jobId`.
+func (r *JobRepository) AddTag(jobId int64, tagId int64) error {
+	_, err := r.DB.Exec(`INSERT INTO jobtag (job_id, tag_id) VALUES (?, ?)`, jobId, tagId)
+	return err
+}
+
+// CreateTag creates a new tag with the specified type and name and returns its database id.
+func (r *JobRepository) CreateTag(tagType string, tagName string) (tagId int64, err error) {
+	res, err := r.DB.Exec("INSERT INTO tag (tag_type, tag_name) VALUES ($1, $2)", tagType, tagName)
+	if err != nil {
+		return 0, err
+	}
+
+	return res.LastInsertId()
+}
+
+func (r *JobRepository) CountTags(user *string) (tags []schema.Tag, counts map[string]int, err error) {
+	tags = make([]schema.Tag, 0, 100)
+	xrows, err := r.DB.Queryx("SELECT * FROM tag")
+	if err != nil {
+		return nil, nil, err
+	}
+
+	for xrows.Next() {
+		var t schema.Tag
+		if err := xrows.StructScan(&t); err != nil {
+			return nil, nil, err
+		}
+		tags = append(tags, t)
+	}
+
+	q := sq.Select("t.tag_name, count(jt.tag_id)").
+		From("tag t").
+		LeftJoin("jobtag jt ON t.id = jt.tag_id").
+		GroupBy("t.tag_name")
+	if user != nil {
+		q = q.Where("jt.job_id IN (SELECT id FROM job WHERE job.user = ?)", *user)
+	}
+
+	rows, err := q.RunWith(r.DB).Query()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	counts = make(map[string]int)
+
+	for rows.Next() {
+		var tagName string
+		var count int
+		err = rows.Scan(&tagName, &count)
+		if err != nil {
+			fmt.Println(err)
+		}
+		counts[tagName] = count
+	}
+	err = rows.Err()
+
+	return
+}
+
+// AddTagOrCreate adds the tag with the specified type and name to the job with the database id `jobId`.
+// If such a tag does not yet exist, it is created.
+func (r *JobRepository) AddTagOrCreate(jobId int64, tagType string, tagName string) (tagId int64, err error) {
+	tagId, exists := r.TagId(tagType, tagName)
+	if !exists {
+		tagId, err = r.CreateTag(tagType, tagName)
+		if err != nil {
+			return 0, err
+		}
+	}
+
+	return tagId, r.AddTag(jobId, tagId)
+}
+
+// TagId returns the database id of the tag with the specified type and name.
+func (r *JobRepository) TagId(tagType string, tagName string) (tagId int64, exists bool) {
+	exists = true
+	if err := sq.Select("id").From("tag").
+		Where("tag.tag_type = ?", tagType).Where("tag.tag_name = ?", tagName).
+		RunWith(r.DB).QueryRow().Scan(&tagId); err != nil {
+		exists = false
+	}
+	return
+}
diff --git a/server.go b/server.go
index 5a78d4a..ba127c8 100644
--- a/server.go
+++ b/server.go
@@ -130,12 +130,12 @@ func setupHomeRoute(i InfoType, r *http.Request) InfoType {
 	}
 
 	state := schema.JobStateRunning
-	runningJobs, err := jobRepo.CountJobs(r.Context(), &state)
+	runningJobs, err := jobRepo.CountJobsPerCluster(r.Context(), &state)
 	if err != nil {
 		log.Errorf("failed to count jobs: %s", err.Error())
 		runningJobs = map[string]int{}
 	}
-	totalJobs, err := jobRepo.CountJobs(r.Context(), nil)
+	totalJobs, err := jobRepo.CountJobsPerCluster(r.Context(), nil)
 	if err != nil {
 		log.Errorf("failed to count jobs: %s", err.Error())
 		totalJobs = map[string]int{}
@@ -200,7 +200,7 @@ func setupTaglistRoute(i InfoType, r *http.Request) InfoType {
 		username = &user.Username
 	}
 
-	tags, counts, err := jobRepo.GetTags(username)
+	tags, counts, err := jobRepo.CountTags(username)
 	tagMap := make(map[string][]map[string]interface{})
 	if err != nil {
 		log.Errorf("GetTags failed: %s", err.Error())
@@ -360,10 +360,7 @@ func main() {
 
 	// Build routes...
 
-	resolver := &graph.Resolver{DB: db}
-	if err := resolver.Init(); err != nil {
-		log.Fatal(err)
-	}
+	resolver := &graph.Resolver{DB: db, Repo: jobRepo}
 	graphQLEndpoint := handler.NewDefaultServer(generated.NewExecutableSchema(generated.Config{Resolvers: resolver}))
 	if os.Getenv("DEBUG") != "1" {
 		graphQLEndpoint.SetRecoverFunc(func(ctx context.Context, err interface{}) error {
diff --git a/test/db.go b/test/db.go
index aa42fb8..8553ef6 100644
--- a/test/db.go
+++ b/test/db.go
@@ -5,6 +5,7 @@ import (
 	"os"
 
 	"github.com/jmoiron/sqlx"
+	_ "github.com/mattn/go-sqlite3"
 )
 
 func InitDB() *sqlx.DB {