Обсуждение: pgsql: amcheck: Support for different header sizes of short varlena dat

amcheck: Support for different header sizes of short varlena datum

In the heap, tuples may contain short varlena datum with both 1B header and 4B
headers.  But the corresponding index tuple should always have such varlena's
with 1B headers.  So, for fingerprinting, we need to convert.

Backpatch to all supported versions.

Discussion: https://postgr.es/m/flat/7bdbe559-d61a-4ae4-a6e1-48abdf3024cc%40postgrespro.ru
Author: Michael Zhilin
Reviewed-by: Alexander Lakhin, Andrey Borodin, Jian He, Alexander Korotkov
Backpatch-through: 12

Branch
------
REL_16_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/a6ddb8ad0ad0947bf86e8cd99c87b156f0956228

Modified Files
--------------
contrib/amcheck/expected/check_btree.out | 13 ++++++++++++
contrib/amcheck/sql/check_btree.sql      | 11 ++++++++++
contrib/amcheck/verify_nbtree.c          | 36 +++++++++++++++++++++++++++-----
3 files changed, 55 insertions(+), 5 deletions(-)