Truncate line pointer array during VACUUM.
Teach VACUUM to truncate the line pointer array of each heap page when a
contiguous group of LP_UNUSED line pointers appear at the end of the
array -- these unused and unreferenced items are excluded. This process
occurs during VACUUM's second pass over the heap, right after LP_DEAD
line pointers on the page (those encountered/pruned during the first
pass) are marked LP_UNUSED.
Truncation avoids line pointer bloat with certain workloads,
particularly those involving continual range DELETEs and bulk INSERTs
against the same table.
Also harden heapam code to check for an out-of-range page offset number
in places where we weren't already doing so.
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAEze2WjgaQc55Y5f5CQd3L=eS5CZcff2Obxp=O6pto8-f0hC4w@mail.gmail.com
Discussion: https://postgr.es/m/CAH2-Wzn6a64PJM1Ggzm=uvx2otsopJMhFQj_g1rAj4GWr3ZSzw@mail.gmail.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/3c3b8a4b26891892bccf3d220580a7f413c0b9ca
Modified Files
--------------
src/backend/access/heap/heapam.c | 22 +++++--
src/backend/access/heap/pruneheap.c | 4 ++
src/backend/access/heap/vacuumlazy.c | 16 ++++-
src/backend/storage/page/bufpage.c | 112 +++++++++++++++++++++++++++++++++--
src/include/storage/bufpage.h | 1 +
5 files changed, 144 insertions(+), 11 deletions(-)