[MASSMAIL]pgsql: Combine freezing and pruning steps in VACUUM

Combine freezing and pruning steps in VACUUM

Execute both freezing and pruning of tuples in the same
heap_page_prune() function, now called heap_page_prune_and_freeze(),
and emit a single WAL record containing all changes. That reduces the
overall amount of WAL generated.

This moves the freezing logic from vacuumlazy.c to the
heap_page_prune_and_freeze() function. The main difference in the
coding is that in vacuumlazy.c, we looked at the tuples after the
pruning had already happened, but in heap_page_prune_and_freeze() we
operate on the tuples before pruning. The heap_prepare_freeze_tuple()
function is now invoked after we have determined that a tuple is not
going to be pruned away.

VACUUM no longer needs to loop through the items on the page after
pruning. heap_page_prune_and_freeze() does all the work. It now
returns the list of dead offsets, including existing LP_DEAD items, to
the caller. Similarly it's now responsible for tracking 'all_visible',
'all_frozen', and 'hastup' on the caller's behalf.

Author: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://www.postgresql.org/message-id/20240330055710.kqg6ii2cdojsxgje@liskov

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6dbb490261a6170a3fc3e326c6983ad63e795047

Modified Files
--------------
src/backend/access/heap/heapam.c         |  67 +--
src/backend/access/heap/heapam_handler.c |   2 +-
src/backend/access/heap/pruneheap.c      | 761 +++++++++++++++++++++++++++----
src/backend/access/heap/vacuumlazy.c     | 435 +++---------------
src/backend/storage/ipc/procarray.c      |   6 +-
src/include/access/heapam.h              |  85 ++--
src/tools/pgindent/typedefs.list         |   2 +-
7 files changed, 813 insertions(+), 545 deletions(-)