Re: Block level parallel vacuum

Hello

I noticed that parallel vacuum uses min_parallel_index_scan_size GUC to skip small indexes but this is not mentioned in documentation for both vacuum command and GUC itself.

+	/* Determine the number of parallel workers to launch */
+	if (lps->lvshared->for_cleanup)
+	{
+		if (lps->lvshared->first_time)
+			nworkers = lps->nindexes_parallel_cleanup +
+				lps->nindexes_parallel_condcleanup - 1;
+		else
+			nworkers = lps->nindexes_parallel_cleanup - 1;
+
+	}
+	else
+		nworkers = lps->nindexes_parallel_bulkdel - 1;

(lazy_parallel_vacuum_indexes)
Perhaps we need to add a comment for future readers, why we reduce the number of workers by 1. Maybe this would be cleaner?

+	/* Determine the number of parallel workers to launch */
+	if (lps->lvshared->for_cleanup)
+	{
+		if (lps->lvshared->first_time)
+			nworkers = lps->nindexes_parallel_cleanup +
+				lps->nindexes_parallel_condcleanup;
+		else
+			nworkers = lps->nindexes_parallel_cleanup;
+
+	}
+	else
+		nworkers = lps->nindexes_parallel_bulkdel;
+
+   /* The leader process will participate */
+   nworkers--;

I have no more comments after reading the patches.

regards, Sergei