Parsed test spec with 2 sessions

starting permutation: s2check s1b s2b s1i s2summ s1c s2c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset     blknum         attnum         allnulls       hasnulls       placeholder    value          

1              0              1              f              f              f              {1 .. 1}       
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
step s2b: BEGIN ISOLATION LEVEL REPEATABLE READ; SELECT 1;
?column?       

1              
step s1i: INSERT INTO brin_iso VALUES (1000);
step s2summ: SELECT brin_summarize_new_values('brinidx'::regclass);
brin_summarize_new_values

1              
step s1c: COMMIT;
step s2c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset     blknum         attnum         allnulls       hasnulls       placeholder    value          

1              0              1              f              f              f              {1 .. 1}       
2              1              1              f              f              f              {1 .. 1000}    

starting permutation: s2check s1b s1i s2vacuum s1c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset     blknum         attnum         allnulls       hasnulls       placeholder    value          

1              0              1              f              f              f              {1 .. 1}       
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
step s1i: INSERT INTO brin_iso VALUES (1000);
step s2vacuum: VACUUM brin_iso;
step s1c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset     blknum         attnum         allnulls       hasnulls       placeholder    value          

1              0              1              f              f              f              {1 .. 1}       
2              1              1              f              f              f              {1 .. 1000}