Parsed test spec with 3 sessions

starting permutation: s3snap s2v s1i s3c s2p s2rec s2t s2size s1j s2check
step s3snap: BEGIN ISOLATION LEVEL REPEATABLE READ; SELECT count(*) > 0 AS snapshot FROM iso_th;
snapshot
--------
t       
(1 row)

step s2v: VACUUM iso_th;
step s1i: INSERT INTO iso_th SELECT g, 'common appended ' || g FROM generate_series(100001, 140000) g;
step s3c: COMMIT;
step s2p: SELECT sift.promote('iso_th_idx') > 0 AS promoted;
promoted
--------
t       
(1 row)

step s2rec: CREATE TABLE iso_th_size AS SELECT relation_blocks AS blocks FROM sift.index_info('iso_th_idx');
step s2t: SELECT sift._test_truncate('iso_th_idx') > 0 AS truncated;
truncated
---------
t        
(1 row)

step s2size: SELECT i.relation_blocks < s.blocks AS shrunk, i.relation_blocks = i.high_water AS sized
			  FROM sift.index_info('iso_th_idx') i, iso_th_size s;
shrunk|sized
------+-----
t     |t    
(1 row)

step s1j: INSERT INTO iso_th SELECT g, 'common again ' || g FROM generate_series(150001, 150100) g;
step s2check: SELECT iso_agree('iso_th', 'common') AS agree, iso_agree('iso_th', 'appended') AS agree_appended, iso_verify('iso_th_idx') AS verified;
agree|agree_appended|verified
-----+--------------+--------
t    |t             |t       
(1 row)