From 3906763f4cd896c5fad68248eb77fbd59299f162 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Mon, 27 Mar 2023 22:50:46 +0200
Subject: [PATCH 3/3] extra tests

---
 contrib/pageinspect/Makefile                |   2 +-
 contrib/pageinspect/expected/brin-fails.out | 152 +++++++++++++++
 contrib/pageinspect/expected/brin2.out      | 201 ++++++++++++++++++++
 contrib/pageinspect/sql/brin-fails.sql      |  86 +++++++++
 contrib/pageinspect/sql/brin2.sql           | 117 ++++++++++++
 5 files changed, 557 insertions(+), 1 deletion(-)
 create mode 100644 contrib/pageinspect/expected/brin-fails.out
 create mode 100644 contrib/pageinspect/expected/brin2.out
 create mode 100644 contrib/pageinspect/sql/brin-fails.sql
 create mode 100644 contrib/pageinspect/sql/brin2.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index 95e030b3969..6a5795fdfd9 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -22,7 +22,7 @@ DATA =  pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.0--1.1.sql
 PGFILEDESC = "pageinspect - functions to inspect contents of database pages"
 
-REGRESS = page btree brin gin gist hash checksum oldextversions
+REGRESS = page btree brin brin2 gin gist hash checksum brin-fails oldextversions
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config
diff --git a/contrib/pageinspect/expected/brin-fails.out b/contrib/pageinspect/expected/brin-fails.out
new file mode 100644
index 00000000000..08479894ec3
--- /dev/null
+++ b/contrib/pageinspect/expected/brin-fails.out
@@ -0,0 +1,152 @@
+create table t (a int);
+-- works
+drop index if exists t_a_idx;
+NOTICE:  index "t_a_idx" does not exist, skipping
+truncate t;
+insert into t values (null), (1);
+create index on t using brin (a);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (1), (null);
+create index on t using brin (a);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (null);
+create index on t using brin (a);
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a);
+insert into t values (null);
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null), (1);
+select brin_summarize_new_values('t_a_idx');
+ brin_summarize_new_values 
+---------------------------
+                         1
+(1 row)
+
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+          2 |      1 |      1 | f        | t        | f           | f     | {1 .. 1}
+(2 rows)
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+select brin_summarize_new_values('t_a_idx');
+ brin_summarize_new_values 
+---------------------------
+                         1
+(1 row)
+
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+          2 |      1 |      1 | f        | t        | f           | f     | {1 .. 1}
+(2 rows)
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+insert into t values (1);
+select brin_summarize_new_values('t_a_idx');
+ brin_summarize_new_values 
+---------------------------
+                         1
+(1 row)
+
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+          2 |      1 |      1 | f        | t        | f           | f     | {1 .. 1}
+(2 rows)
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+insert into t values (null);
+select brin_summarize_new_values('t_a_idx');
+ brin_summarize_new_values 
+---------------------------
+                         1
+(1 row)
+
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+          2 |      1 |      1 | f        | t        | f           | f     | {1 .. 1}
+(2 rows)
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+insert into t values (null);
+select brin_summarize_new_values('t_a_idx');
+ brin_summarize_new_values 
+---------------------------
+                         1
+(1 row)
+
+insert into t values (null);
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+          2 |      1 |      1 | f        | t        | f           | f     | {1 .. 1}
+(2 rows)
+
+drop table t;
diff --git a/contrib/pageinspect/expected/brin2.out b/contrib/pageinspect/expected/brin2.out
new file mode 100644
index 00000000000..8406a792cd3
--- /dev/null
+++ b/contrib/pageinspect/expected/brin2.out
@@ -0,0 +1,201 @@
+create table t (a int);
+-- 
+drop index if exists t_a_idx;
+NOTICE:  index "t_a_idx" does not exist, skipping
+truncate t;
+create index on t using brin (a);
+-- empty range, all_nulls=true (default)
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value 
+------------+--------+--------+----------+----------+-------------+-------+-------
+          1 |      0 |      1 | t        | f        | f           | t     | 
+(1 row)
+
+-- insert NULL value, range no longer empty, all_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value 
+------------+--------+--------+----------+----------+-------------+-------+-------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+(1 row)
+
+-- another NULL value, still all_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value 
+------------+--------+--------+----------+----------+-------------+-------+-------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+(1 row)
+
+-- not-NULL value, switches to has_nulls=true
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- reinsert the not-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- another not-NULL value, still has_nulls=true, range extends
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+-- another NULL value, still has_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+--
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a);
+-- empty range, all_nulls=true (default)
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value 
+------------+--------+--------+----------+----------+-------------+-------+-------
+          1 |      0 |      1 | t        | f        | f           | t     | 
+(1 row)
+
+-- insert non-NULL value, range no longer empty, all_nulls=false
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | f        | f           | f     | {1 .. 1}
+(1 row)
+
+-- re-insert non-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | f        | f           | f     | {1 .. 1}
+(1 row)
+
+-- insert NULL value, has_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- another not-NULL value, still has_nulls=true, range expands
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+-- another NULL value, still has_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+--
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (1); -- start with one non-NULL value
+create index on t using brin (a);
+-- non-empty range, all_nulls/has_nulls=false
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | f        | f           | f     | {1 .. 1}
+(1 row)
+
+-- re-insert the non-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | f        | f           | f     | {1 .. 1}
+(1 row)
+
+-- insert another non-NULL value, null flags stay the same
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | f        | f           | f     | {1 .. 2}
+(1 row)
+
+-- insert NULL value, has_nulls=true
+insert into t values (null);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+--
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (NULL); -- start with one non-NULL value
+create index on t using brin (a);
+-- non-empty range, all_nulls=true
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value 
+------------+--------+--------+----------+----------+-------------+-------+-------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+(1 row)
+
+-- re-insert NULL, stays the same
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value 
+------------+--------+--------+----------+----------+-------------+-------+-------
+          1 |      0 |      1 | t        | f        | f           | f     | 
+(1 row)
+
+-- insert a non-NULL value, switches to has_nulls=true
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- re-insert the non-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 1}
+(1 row)
+
+-- insert another the non-NULL value, stays the same, range updated
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+-- insert NULL value, stays the same
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
+------------+--------+--------+----------+----------+-------------+-------+----------
+          1 |      0 |      1 | f        | t        | f           | f     | {1 .. 2}
+(1 row)
+
+drop table t;
diff --git a/contrib/pageinspect/sql/brin-fails.sql b/contrib/pageinspect/sql/brin-fails.sql
new file mode 100644
index 00000000000..e5b37fa6b12
--- /dev/null
+++ b/contrib/pageinspect/sql/brin-fails.sql
@@ -0,0 +1,86 @@
+create table t (a int);
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (null), (1);
+create index on t using brin (a);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (1), (null);
+create index on t using brin (a);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (null);
+create index on t using brin (a);
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a);
+insert into t values (null);
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null), (1);
+select brin_summarize_new_values('t_a_idx');
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+select brin_summarize_new_values('t_a_idx');
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- works
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+insert into t values (1);
+select brin_summarize_new_values('t_a_idx');
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+insert into t values (null);
+select brin_summarize_new_values('t_a_idx');
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- fails
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a) with (pages_per_range=1);
+insert into t select null from generate_series(1,291); -- fill first page
+insert into t values (null);
+insert into t values (null);
+select brin_summarize_new_values('t_a_idx');
+insert into t values (null);
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+drop table t;
diff --git a/contrib/pageinspect/sql/brin2.sql b/contrib/pageinspect/sql/brin2.sql
new file mode 100644
index 00000000000..501252e7b8c
--- /dev/null
+++ b/contrib/pageinspect/sql/brin2.sql
@@ -0,0 +1,117 @@
+create table t (a int);
+
+-- 
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a);
+
+-- empty range, all_nulls=true (default)
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert NULL value, range no longer empty, all_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- another NULL value, still all_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- not-NULL value, switches to has_nulls=true
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- reinsert the not-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- another not-NULL value, still has_nulls=true, range extends
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- another NULL value, still has_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+
+--
+drop index if exists t_a_idx;
+truncate t;
+create index on t using brin (a);
+
+-- empty range, all_nulls=true (default)
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert non-NULL value, range no longer empty, all_nulls=false
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- re-insert non-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert NULL value, has_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- another not-NULL value, still has_nulls=true, range expands
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- another NULL value, still has_nulls=true
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+
+--
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (1); -- start with one non-NULL value
+create index on t using brin (a);
+
+-- non-empty range, all_nulls/has_nulls=false
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- re-insert the non-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert another non-NULL value, null flags stay the same
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert NULL value, has_nulls=true
+insert into t values (null);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+
+--
+drop index if exists t_a_idx;
+truncate t;
+insert into t values (NULL); -- start with one non-NULL value
+create index on t using brin (a);
+
+-- non-empty range, all_nulls=true
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- re-insert NULL, stays the same
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert a non-NULL value, switches to has_nulls=true
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- re-insert the non-NULL value, stays the same
+insert into t values (1);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert another the non-NULL value, stays the same, range updated
+insert into t values (2);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+-- insert NULL value, stays the same
+insert into t values (NULL);
+select * from brin_page_items(get_raw_page('t_a_idx', 2), 't_a_idx'::regclass);
+
+
+drop table t;
-- 
2.39.2