CREATE TABLE test1 (a int, b text);
INSERT INTO test1 VALUES (1, 'one');
CREATE INDEX test1_a_idx ON test1 USING brin (a);
SELECT brin_page_type(get_raw_page('test1_a_idx', 0));
 brin_page_type 
----------------
 meta
(1 row)

SELECT brin_page_type(get_raw_page('test1_a_idx', 1));
 brin_page_type 
----------------
 revmap
(1 row)

SELECT brin_page_type(get_raw_page('test1_a_idx', 2));
 brin_page_type 
----------------
 regular
(1 row)

SELECT * FROM brin_metapage_info(get_raw_page('test1_a_idx', 0));
   magic    | version | pagesperrange | lastrevmappage 
------------+---------+---------------+----------------
 0xA8109CFA |       1 |           128 |              1
(1 row)

SELECT * FROM brin_metapage_info(get_raw_page('test1_a_idx', 1));
ERROR:  page is not a BRIN page of type "metapage"
DETAIL:  Expected special type 0000f091, got 0000f092.
SELECT * FROM brin_revmap_data(get_raw_page('test1_a_idx', 0)) LIMIT 5;
ERROR:  page is not a BRIN page of type "revmap"
DETAIL:  Expected special type 0000f092, got 0000f091.
SELECT * FROM brin_revmap_data(get_raw_page('test1_a_idx', 1)) LIMIT 5;
 pages 
-------
 (2,1)
 (0,0)
 (0,0)
 (0,0)
 (0,0)
(5 rows)

SELECT * FROM brin_page_items(get_raw_page('test1_a_idx', 2), 'test1_a_idx')
    ORDER BY blknum, attnum LIMIT 5;
 itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |  value   
------------+--------+--------+----------+----------+-------------+-------+----------
          1 |      0 |      1 | f        | f        | f           | f     | {1 .. 1}
(1 row)

-- Mask DETAIL messages as these are not portable across architectures.
\set VERBOSITY terse
-- Failures for non-BRIN index.
CREATE INDEX test1_a_btree ON test1 (a);
SELECT brin_page_items(get_raw_page('test1_a_btree', 0), 'test1_a_btree');
ERROR:  "test1_a_btree" is not a BRIN index
SELECT brin_page_items(get_raw_page('test1_a_btree', 0), 'test1_a_idx');
ERROR:  input page is not a valid BRIN page
-- Invalid special area size
SELECT brin_page_type(get_raw_page('test1', 0));
ERROR:  input page is not a valid BRIN page
SELECT * FROM brin_metapage_info(get_raw_page('test1', 0));
ERROR:  input page is not a valid BRIN page
SELECT * FROM brin_revmap_data(get_raw_page('test1', 0));
ERROR:  input page is not a valid BRIN page
\set VERBOSITY default
-- Tests with all-zero pages.
SHOW block_size \gset
SELECT brin_page_type(decode(repeat('00', :block_size), 'hex'));
 brin_page_type 
----------------
 
(1 row)

SELECT brin_page_items(decode(repeat('00', :block_size), 'hex'), 'test1_a_idx');
 brin_page_items 
-----------------
(0 rows)

SELECT brin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 brin_metapage_info 
--------------------
 
(1 row)

SELECT brin_revmap_data(decode(repeat('00', :block_size), 'hex'));
 brin_revmap_data 
------------------
 
(1 row)

-- Test that partial indexes have all pages, including empty ones.
CREATE TABLE test2 (a int);
INSERT INTO test2 SELECT i FROM generate_series(1,1000) s(i);
-- No rows match the index predicate, make sure the index has the right number
-- of ranges (same as number of page ranges).
CREATE INDEX ON test2 USING brin (a) WITH (pages_per_range=1) WHERE (a IS NULL);
ANALYZE test2;
-- Does the index have one summary of the relation?
SELECT (COUNT(*) = (SELECT relpages FROM pg_class WHERE relname = 'test2')) AS ranges_do_match
 FROM generate_series((SELECT (lastrevmappage + 1) FROM brin_metapage_info(get_raw_page('test2_a_idx', 0))),
                      (SELECT (relpages - 1) FROM pg_class WHERE relname = 'test2_a_idx')) AS pages(p),
      LATERAL brin_page_items(get_raw_page('test2_a_idx', p), 'test2_a_idx') AS items;
 ranges_do_match 
-----------------
 t
(1 row)

DROP TABLE test1;
DROP TABLE test2;