feat(backend): Update db table config with Primary key to improve db read performance (kubeflow#1116)

Author: Tomcli

backend/src/apiserver/model/db_status.go

@@ -15,5 +15,5 @@
 package model
 
 type DBStatus struct {
-	HaveSamplesLoaded bool `gorm:"column:HaveSamplesLoaded; not null"`
+	HaveSamplesLoaded bool `gorm:"column:HaveSamplesLoaded; not null; primary_key"`
 }

backend/src/apiserver/model/default_experiment.go

@@ -15,5 +15,5 @@
 package model
 
 type DefaultExperiment struct {
-	DefaultExperimentId string `gorm:"column:DefaultExperimentId; not null"`
+	DefaultExperimentId string `gorm:"column:DefaultExperimentId; not null; primary_key"`
 }