Обсуждение: pgsql: Further harden nbtree posting split code.

Further harden nbtree posting split code.

Add more defensive checks around posting list split code.  These should
detect corruption involving duplicate table TIDs earlier and more
reliably than any existing check.

Follow up to commit 8f72bbac.

Discussion: https://postgr.es/m/CAH2-WzkrSY_kjyd1_M5xJK1uM0govJXMxPn8JUSvwcUOiHuWVw@mail.gmail.com
Backpatch: 13-, where nbtree deduplication was introduced.

Branch
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REL_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/f8cce4a3d88ccce830086bc80b563bd152f4955f

Modified Files
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src/backend/access/nbtree/nbtinsert.c | 24 ++++++++++++++++++++++--
src/backend/access/nbtree/nbtsearch.c | 17 +++++++++++++++++
2 files changed, 39 insertions(+), 2 deletions(-)