0002-Vacuum-free-dead_tuples-sooner.patch

From 24fa0815d915cc31ae455ef60585f54a33dbd09c Mon Sep 17 00:00:00 2001
From: Claudio Freire <klaussfreire@gmail.com>
Date: Fri, 2 Sep 2016 23:21:01 -0300
Subject: [PATCH 2/2] Vacuum: free dead_tuples sooner

Frees the dead_tuples array sooner, decreasing impact of huge settings
for autovacuum_work_mem or maintainance_work_mem during lazy vacuum.
---
 src/backend/commands/vacuumlazy.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index 2c98da4..dbe2040 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -155,6 +155,7 @@ static void lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats);
 static BlockNumber count_nondeletable_pages(Relation onerel,
 						 LVRelStats *vacrelstats);
 static void lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks);
+static void lazy_space_dealloc(LVRelStats *vacrelstats);
 static void lazy_record_dead_tuple(LVRelStats *vacrelstats,
 					   ItemPointer itemptr);
 static bool lazy_tid_reaped(ItemPointer itemptr, void *state);
@@ -1310,6 +1311,8 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats,
 	for (i = 0; i < nindexes; i++)
 		lazy_cleanup_index(Irel[i], indstats[i], vacrelstats);
 
+	lazy_space_dealloc(vacrelstats);
+
 	/* If no indexes, make log report that lazy_vacuum_heap would've made */
 	if (vacuumed_pages)
 		ereport(elevel,
@@ -1973,6 +1976,18 @@ lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks)
 }
 
 /*
+ * lazy_space_dealloc - free lazy vacuum work mem
+ */
+static void
+lazy_space_dealloc(LVRelStats *vacrelstats)
+{
+	if (vacrelstats->dead_tuples != NULL) {
+		pfree(vacrelstats->dead_tuples);
+		vacrelstats->dead_tuples = NULL;
+	}
+}
+
+/*
  * lazy_record_dead_tuple - remember one deletable tuple
  */
 static void
-- 
2.6.6