search: fix search to limit dashboards better

Change the query to first select the dashboards, apply the limit then
join with tags. Means the limit will apply to the number of dashboards
returned in the search. The disadvantage is that the query will return
more rows than the limit, no. of dashboards x no. of tags. So hard limit
set to 5000 for all rows.

pkg/services/sqlstore/dashboard.go

@@ -189,14 +189,13 @@ type DashboardSearchProjection struct {
 }
 
 func findDashboards(query *search.FindPersistedDashboardsQuery) ([]DashboardSearchProjection, error) {
+	var sql bytes.Buffer
+	params := make([]interface{}, 0)
 	limit := query.Limit
 	if limit == 0 {
 		limit = 1000
 	}
 
-	var sql bytes.Buffer
-	params := make([]interface{}, 0)
-
 	sql.WriteString(`
 	SELECT
 		dashboard.id,
@@ -207,36 +206,69 @@ func findDashboards(query *search.FindPersistedDashboardsQuery) ([]DashboardSear
 		dashboard.folder_id,
 		folder.slug as folder_slug,
 		folder.title as folder_title
-	FROM (
-		SELECT
-			dashboard.id FROM dashboard
-			LEFT OUTER JOIN dashboard_tag ON dashboard_tag.dashboard_id = dashboard.id
-	`)
+	FROM `)
 
 	// add tags filter
 	if len(query.Tags) > 0 {
-		sql.WriteString(` WHERE dashboard_tag.term IN (?` + strings.Repeat(",?", len(query.Tags)-1) + `)`)
+		sql.WriteString(
+			`(
+		SELECT
+			dashboard.id FROM dashboard
+			LEFT OUTER JOIN dashboard_tag ON dashboard_tag.dashboard_id = dashboard.id
+		`)
+		if query.IsStarred {
+			sql.WriteString(" INNER JOIN star on star.dashboard_id = dashboard.id")
+		}
+
+		sql.WriteString(` WHERE dashboard_tag.term IN (?` + strings.Repeat(",?", len(query.Tags)-1) + `) AND `)
 		for _, tag := range query.Tags {
 			params = append(params, tag)
 		}
+		params = createSearchWhereClause(query, &sql, params)
+		fmt.Printf("params2 %v", params)
+
+		// this ends the inner select (tag filtered part)
+		sql.WriteString(`
+			GROUP BY dashboard.id HAVING COUNT(dashboard.id) >= ?
+			LIMIT ?) as ids
+			INNER JOIN dashboard on ids.id = dashboard.id
+		`)
+
+		params = append(params, len(query.Tags))
+		params = append(params, limit)
+	} else {
+		sql.WriteString(`( SELECT dashboard.id FROM dashboard `)
+		if query.IsStarred {
+			sql.WriteString(" INNER JOIN star on star.dashboard_id = dashboard.id")
+		}
+		sql.WriteString(` WHERE `)
+		params = createSearchWhereClause(query, &sql, params)
+
+		sql.WriteString(`
+			LIMIT ?) as ids
+		INNER JOIN dashboard on ids.id = dashboard.id
+		`)
+		params = append(params, limit)
 	}
 
-	// this ends the inner select (tag filtered part)
 	sql.WriteString(`
-		  GROUP BY dashboard.id HAVING COUNT(dashboard.id) >= ?
-		  ORDER BY dashboard.title ASC LIMIT ?) as ids`)
-	params = append(params, len(query.Tags))
-	params = append(params, limit)
-
-	sql.WriteString(`
-		INNER JOIN dashboard on ids.id = dashboard.id
 		LEFT OUTER JOIN dashboard folder on folder.id = dashboard.folder_id
 		LEFT OUTER JOIN dashboard_tag on dashboard.id = dashboard_tag.dashboard_id`)
-	if query.IsStarred {
-		sql.WriteString(" INNER JOIN star on star.dashboard_id = dashboard.id")
+
+	sql.WriteString(fmt.Sprintf(" ORDER BY dashboard.title ASC LIMIT 5000"))
+
+	var res []DashboardSearchProjection
+
+	err := x.Sql(sql.String(), params...).Find(&res)
+	if err != nil {
+		return nil, err
 	}
 
-	sql.WriteString(` WHERE dashboard.org_id=?`)
+	return res, nil
+}
+
+func createSearchWhereClause(query *search.FindPersistedDashboardsQuery, sql *bytes.Buffer, params []interface{}) []interface{} {
+	sql.WriteString(` dashboard.org_id=?`)
 	params = append(params, query.SignedInUser.OrgId)
 
 	if query.IsStarred {
@@ -253,16 +285,17 @@ func findDashboards(query *search.FindPersistedDashboardsQuery) ([]DashboardSear
 
 	if query.SignedInUser.OrgRole != m.ROLE_ADMIN {
 		allowedDashboardsSubQuery := ` AND (dashboard.has_acl = 0 OR dashboard.id in (
-		SELECT distinct d.id AS DashboardId
+			SELECT distinct d.id AS DashboardId
 			FROM dashboard AS d
-	      LEFT JOIN dashboard_acl as da on d.folder_id = da.dashboard_id or d.id = da.dashboard_id
-	      LEFT JOIN user_group_member as ugm on ugm.user_group_id =  da.user_group_id
-	      LEFT JOIN org_user ou on ou.role = da.role
+	      		LEFT JOIN dashboard_acl as da on d.folder_id = da.dashboard_id or d.id = da.dashboard_id
+	      		LEFT JOIN user_group_member as ugm on ugm.user_group_id =  da.user_group_id
+	      		LEFT JOIN org_user ou on ou.role = da.role
 			WHERE
 			  d.has_acl = 1 and
 				(da.user_id = ? or ugm.user_id = ? or ou.id is not null)
 			  and d.org_id = ?
-			  ))`
+			)
+		)`
 
 		sql.WriteString(allowedDashboardsSubQuery)
 		params = append(params, query.SignedInUser.UserId, query.SignedInUser.UserId, query.SignedInUser.OrgId)
@@ -286,16 +319,7 @@ func findDashboards(query *search.FindPersistedDashboardsQuery) ([]DashboardSear
 		params = append(params, query.FolderId)
 	}
 
-	sql.WriteString(fmt.Sprintf(" ORDER BY dashboard.title ASC LIMIT 1000"))
-
-	var res []DashboardSearchProjection
-
-	err := x.Sql(sql.String(), params...).Find(&res)
-	if err != nil {
-		return nil, err
-	}
-
-	return res, nil
+	return params
 }
 
 func SearchDashboards(query *search.FindPersistedDashboardsQuery) error {

pkg/services/sqlstore/dashboard_test.go

@@ -3,6 +3,7 @@ package sqlstore
 import (
 	"testing"
 
+	"github.com/go-xorm/xorm"
 	. "github.com/smartystreets/goconvey/convey"
 
 	"github.com/grafana/grafana/pkg/components/simplejson"
@@ -12,9 +13,10 @@ import (
 )
 
 func TestDashboardDataAccess(t *testing.T) {
+	var x *xorm.Engine
 
 	Convey("Testing DB", t, func() {
-		InitTestDB(t)
+		x = InitTestDB(t)
 
 		Convey("Given saved dashboard", func() {
 			savedFolder := insertTestDashboard("1 test dash folder", 1, 0, true, "prod", "webapp")

pkg/services/sqlstore/datasource_test.go

@@ -11,11 +11,10 @@ import (
 	"github.com/grafana/grafana/pkg/services/sqlstore/sqlutil"
 )
 
-func InitTestDB(t *testing.T) {
+func InitTestDB(t *testing.T) *xorm.Engine {
 	x, err := xorm.NewEngine(sqlutil.TestDB_Sqlite3.DriverName, sqlutil.TestDB_Sqlite3.ConnStr)
 	//x, err := xorm.NewEngine(sqlutil.TestDB_Mysql.DriverName, sqlutil.TestDB_Mysql.ConnStr)
 	//x, err := xorm.NewEngine(sqlutil.TestDB_Postgres.DriverName, sqlutil.TestDB_Postgres.ConnStr)
-	// x.ShowSQL()
 
 	// x.ShowSQL()
 
@@ -28,6 +27,8 @@ func InitTestDB(t *testing.T) {
 	if err := SetEngine(x); err != nil {
 		t.Fatal(err)
 	}
+
+	return x
 }
 
 type Test struct {