Bug Fix: Fix lingering type issues (#828)

* Fix postmaster type issue
* Disable postmaster collector by default

---------

Signed-off-by: Felix Yuan <felix.yuan@reddit.com>

Author: Sticksman

collector/pg_postmaster.go

@@ -23,7 +23,7 @@ import (
 const postmasterSubsystem = "postmaster"
 
 func init() {
-	registerCollector(postmasterSubsystem, defaultEnabled, NewPGPostmasterCollector)
+	registerCollector(postmasterSubsystem, defaultDisabled, NewPGPostmasterCollector)
 }
 
 type PGPostmasterCollector struct {
@@ -44,7 +44,7 @@ var (
 		[]string{}, nil,
 	)
 
-	pgPostmasterQuery = "SELECT pg_postmaster_start_time from pg_postmaster_start_time();"
+	pgPostmasterQuery = "SELECT extract(epoch from pg_postmaster_start_time) from pg_postmaster_start_time();"
 )
 
 func (c *PGPostmasterCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {

collector/pg_process_idle.go

@@ -84,7 +84,7 @@ func (PGProcessIdleCollector) Update(ctx context.Context, instance *instance, ch
 	var applicationName sql.NullString
 	var secondsSum sql.NullInt64
 	var secondsCount sql.NullInt64
-	var seconds []int64
+	var seconds []uint64
 	var secondsBucket []uint64
 
 	err := row.Scan(&applicationName, &secondsSum, &secondsCount, &seconds, &secondsBucket)