-- The slot of a record in a write buffer page of a sift_table comes from disk: one that, or whose length, reaches past the page is
-- corruption (the readers dereference it), not a pointer out of the page.
CREATE EXTENSION pg_sift;
CREATE EXTENSION pg_sift_test;
SELECT sift._test_tbl_page_rec(64, 16) AS inside;
 inside 
--------
 t
(1 row)

SELECT sift._test_tbl_page_rec(0, 0) AS empty_slot;
 empty_slot 
------------
 f
(1 row)

SELECT sift._test_tbl_page_rec(65532, 0) AS slot_past_page;
ERROR:  sift_table write buffer page holds a record that reaches past the page
SELECT sift._test_tbl_page_rec(100, 60000) AS length_past_page;
ERROR:  sift_table write buffer page holds a record that reaches past the page
-- the edge: the largest record a page holds (also a bare header at the very end) is valid, one alignment unit more is not, and a slot off the alignment of the record is corruption too
SELECT sift._test_tbl_page_rec_end(100, 0) AS largest_record;
 largest_record 
----------------
 t
(1 row)

SELECT sift._test_tbl_page_rec_end(0, 0) AS header_at_the_end;
 header_at_the_end 
-------------------
 t
(1 row)

SELECT sift._test_tbl_page_rec_end(100, 4) AS record_past_the_end;
ERROR:  sift_table write buffer page holds a record that reaches past the page
SELECT sift._test_tbl_page_rec_end(0, 4) AS header_past_the_end;
ERROR:  sift_table write buffer page holds a record that reaches past the page
SELECT sift._test_tbl_page_rec_end(100, 1) AS misaligned_slot;
ERROR:  sift_table write buffer page holds a record at a misaligned offset
DROP EXTENSION pg_sift_test;
DROP EXTENSION pg_sift;