From: Nitin Jadhav <nitinjadhavpostgres@gmail.com>
Date: Sat, 15 May 2021 14:40:45 +0530
Subject: [PATCH 1/5] Removed extra memory allocations from create_list_bounds

---
 src/backend/partitioning/partbounds.c | 64 +++++++++++++++------------
 1 file changed, 35 insertions(+), 29 deletions(-)

diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index 7925fcce3b..d0c263d435 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -432,6 +432,32 @@ create_hash_bounds(PartitionBoundSpec **boundspecs, int nparts,
 	return boundinfo;
 }
 
+/*
+ * get_non_null_count_list_bounds
+ * 		Calculates the total number of non null bound values of
+ * 		all the partitions.
+ */
+static int
+get_non_null_count_list_bounds(PartitionBoundSpec **boundspecs, int nparts)
+{
+	int	i = 0;
+	int count = 0;
+
+	for (i = 0; i < nparts; i++)
+	{
+		ListCell   *c;
+
+		foreach(c, boundspecs[i]->listdatums)
+		{
+			Const   *val = castNode(Const, lfirst(c));
+
+			if (!val->constisnull)
+				count++;
+		}
+	}
+
+	return count;
+}
 /*
  * create_list_bounds
  *		Create a PartitionBoundInfo for a list partitioned table
@@ -442,13 +468,12 @@ create_list_bounds(PartitionBoundSpec **boundspecs, int nparts,
 {
 	PartitionBoundInfo boundinfo;
 	PartitionListValue **all_values = NULL;
-	ListCell   *cell;
 	int			i = 0;
+	int			j = 0;
 	int			ndatums = 0;
 	int			next_index = 0;
 	int			default_index = -1;
 	int			null_index = -1;
-	List	   *non_null_values = NIL;
 
 	boundinfo = (PartitionBoundInfoData *)
 		palloc0(sizeof(PartitionBoundInfoData));
@@ -457,6 +482,10 @@ create_list_bounds(PartitionBoundSpec **boundspecs, int nparts,
 	boundinfo->null_index = -1;
 	boundinfo->default_index = -1;
 
+	ndatums = get_non_null_count_list_bounds(boundspecs, nparts);
+	all_values = (PartitionListValue **)
+		palloc(ndatums * sizeof(PartitionListValue *));
+
 	/* Create a unified list of non-null values across all partitions. */
 	for (i = 0; i < nparts; i++)
 	{
@@ -480,14 +509,14 @@ create_list_bounds(PartitionBoundSpec **boundspecs, int nparts,
 		foreach(c, spec->listdatums)
 		{
 			Const	   *val = castNode(Const, lfirst(c));
-			PartitionListValue *list_value = NULL;
 
 			if (!val->constisnull)
 			{
-				list_value = (PartitionListValue *)
+				all_values[j] = (PartitionListValue *)
 					palloc0(sizeof(PartitionListValue));
-				list_value->index = i;
-				list_value->value = val->constvalue;
+				all_values[j]->index = i;
+				all_values[j]->value = val->constvalue;
+				j++;
 			}
 			else
 			{
@@ -499,32 +528,9 @@ create_list_bounds(PartitionBoundSpec **boundspecs, int nparts,
 					elog(ERROR, "found null more than once");
 				null_index = i;
 			}
-
-			if (list_value)
-				non_null_values = lappend(non_null_values, list_value);
 		}
 	}
 
-	ndatums = list_length(non_null_values);
-
-	/*
-	 * Collect all list values in one array. Alongside the value, we also save
-	 * the index of partition the value comes from.
-	 */
-	all_values = (PartitionListValue **)
-		palloc(ndatums * sizeof(PartitionListValue *));
-	i = 0;
-	foreach(cell, non_null_values)
-	{
-		PartitionListValue *src = lfirst(cell);
-
-		all_values[i] = (PartitionListValue *)
-			palloc(sizeof(PartitionListValue));
-		all_values[i]->value = src->value;
-		all_values[i]->index = src->index;
-		i++;
-	}
-
 	qsort_arg(all_values, ndatums, sizeof(PartitionListValue *),
 			  qsort_partition_list_value_cmp, (void *) key);
 
-- 
2.17.0


--T4sUOijqQbZv57TR
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Content-Disposition: attachment;
 filename="0002-allocate-the-PartitionListValue-as-a-single-chunk.patch"