From 0372cba1ea87d6eb10e21133461c1db525dbcf06 Mon Sep 17 00:00:00 2001
From: David Rowley <dgrowley@gmail.com>
Date: Thu, 7 Jul 2022 13:02:29 +1200
Subject: [PATCH v1 1/2] Track NOT NULL columns in RelOptInfo for base
 relations

Author: Andy Fan
Discussion: https://postgr.es/m/CAKU4AWpUA8dyVSU1nfCJz71mu6VEjbGS1uy8azrt5CdyoZqGQA%40mail.gmail.com
---
 src/backend/optimizer/util/plancat.c | 10 ++++++++++
 src/backend/optimizer/util/relnode.c |  2 ++
 src/include/nodes/pathnodes.h        |  2 ++
 3 files changed, 14 insertions(+)

diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 5012bfe142..7111284221 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -472,6 +472,16 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 	if (inhparent && relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 		set_relation_partition_info(root, rel, relation);
 
+	Assert(rel->notnullattrs == NULL);
+	for(int i = 0; i < relation->rd_att->natts; i++)
+	{
+		FormData_pg_attribute *attr = &relation->rd_att->attrs[i];
+
+		if (attr->attnotnull && !attr->attisdropped)
+			rel->notnullattrs = bms_add_member(rel->notnullattrs,
+											   attr->attnum - FirstLowInvalidHeapAttributeNumber);
+	}
+
 	table_close(relation, NoLock);
 
 	/*
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 520409f4ba..f7be6548ef 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -227,6 +227,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
 	rel->lateral_vars = NIL;
 	rel->indexlist = NIL;
 	rel->statlist = NIL;
+	rel->notnullattrs = NULL;
 	rel->pages = 0;
 	rel->tuples = 0;
 	rel->allvisfrac = 0;
@@ -641,6 +642,7 @@ build_join_rel(PlannerInfo *root,
 	joinrel->lateral_referencers = NULL;
 	joinrel->indexlist = NIL;
 	joinrel->statlist = NIL;
+	joinrel->notnullattrs = NULL;
 	joinrel->pages = 0;
 	joinrel->tuples = 0;
 	joinrel->allvisfrac = 0;
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index b88cfb8dc0..5f81ecc3b5 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -758,6 +758,8 @@ typedef struct RelOptInfo
 	List	   *indexlist;
 	/* list of StatisticExtInfo */
 	List	   *statlist;
+	/* NOT NULL attributes offset by FirstLowInvalidHeapAttributeNumber */
+	Bitmapset	   *notnullattrs;
 	/* size estimates derived from pg_class */
 	BlockNumber pages;
 	Cardinality tuples;
-- 
2.35.1.windows.2