enrich GC logging messages

when there is a lot of data to be GC, it
would be useful to have richer understanding
of what's happening via logs. This commit
changes the completed log messages to info
since this is something operators would want
to monitor under normal operations, and
also enriches the error message to understand
where is it stuck deleting

internal/datastore/common/gc.go

@@ -123,6 +123,9 @@ func startGarbageCollectorWithMaxElapsedTime(ctx context.Context, gc GarbageColl
 
 		case <-time.After(nextInterval):
 			log.Ctx(ctx).Info().
+				Dur("interval", nextInterval).
+				Dur("window", window).
+				Dur("timeout", timeout).
 				Msg("running garbage collection worker")
 
 			err := RunGarbageCollection(gc, window, timeout)
@@ -178,7 +181,7 @@ func RunGarbageCollection(gc GarbageCollector, window, timeout time.Duration) er
 	}
 
 	collectionDuration := time.Since(startTime)
-	log.Ctx(ctx).Debug().
+	log.Ctx(ctx).Info().
 		Stringer("highestTxID", watermark).
 		Dur("duration", collectionDuration).
 		Time("nowTime", now).

internal/datastore/postgres/gc.go

@@ -66,11 +66,12 @@ func (pgd *pgDatastore) TxIDBefore(ctx context.Context, before time.Time) (datas
 	return postgresRevision{snapshot}, nil
 }
 
-func (pgd *pgDatastore) DeleteBeforeTx(ctx context.Context, txID datastore.Revision) (removed common.DeletionCounts, err error) {
+func (pgd *pgDatastore) DeleteBeforeTx(ctx context.Context, txID datastore.Revision) (common.DeletionCounts, error) {
 	revision := txID.(postgresRevision)
 
 	minTxAlive := newXid8(revision.snapshot.xmin)
-
+	removed := common.DeletionCounts{}
+	var err error
 	// Delete any relationship rows that were already dead when this transaction started
 	removed.Relationships, err = pgd.batchDelete(
 		ctx,
@@ -79,7 +80,7 @@ func (pgd *pgDatastore) DeleteBeforeTx(ctx context.Context, txID datastore.Revis
 		sq.Lt{colDeletedXid: minTxAlive},
 	)
 	if err != nil {
-		return
+		return removed, fmt.Errorf("failed to GC relationships table: %w", err)
 	}
 
 	// Delete all transaction rows with ID < the transaction ID.
@@ -93,7 +94,7 @@ func (pgd *pgDatastore) DeleteBeforeTx(ctx context.Context, txID datastore.Revis
 		sq.Lt{colXID: minTxAlive},
 	)
 	if err != nil {
-		return
+		return removed, fmt.Errorf("failed to GC transactions table: %w", err)
 	}
 
 	// Delete any namespace rows with deleted_transaction <= the transaction ID.
@@ -104,10 +105,10 @@ func (pgd *pgDatastore) DeleteBeforeTx(ctx context.Context, txID datastore.Revis
 		sq.Lt{colDeletedXid: minTxAlive},
 	)
 	if err != nil {
-		return
+		return removed, fmt.Errorf("failed to GC namespaces table: %w", err)
 	}
 
-	return
+	return removed, err
 }
 
 func (pgd *pgDatastore) batchDelete(
@@ -116,7 +117,7 @@ func (pgd *pgDatastore) batchDelete(
 	pkCols []string,
 	filter sqlFilter,
 ) (int64, error) {
-	sql, args, err := psql.Select(pkCols...).From(tableName).Where(filter).Limit(batchDeleteSize).ToSql()
+	sql, args, err := psql.Select(pkCols...).From(tableName).Where(filter).Limit(gcBatchDeleteSize).ToSql()
 	if err != nil {
 		return -1, err
 	}
@@ -137,7 +138,7 @@ func (pgd *pgDatastore) batchDelete(
 
 		rowsDeleted := cr.RowsAffected()
 		deletedCount += rowsDeleted
-		if rowsDeleted < batchDeleteSize {
+		if rowsDeleted < gcBatchDeleteSize {
 			break
 		}
 	}

internal/datastore/postgres/postgres.go

@@ -69,7 +69,7 @@ const (
 
 	tracingDriverName = "postgres-tracing"
 
-	batchDeleteSize = 1000
+	gcBatchDeleteSize = 1000
 
 	livingTupleConstraint = "uq_relation_tuple_living_xid"
 )