Thread: pgsql: Explain pruning pgstats accounting subtleties.
Explain pruning pgstats accounting subtleties. Add a comment explaining why the pgstats accounting used during opportunistic heap pruning operations (to maintain the current number of dead tuples in the relation) needs to compensate by subtracting away the number of new LP_DEAD items. This is needed so it can avoid completely forgetting about tuples that become LP_DEAD items during pruning -- they should still count. It seems more natural to discuss this issue at the only relevant call site (opportunistic pruning), since the same issue does not apply to the only other caller (the VACUUM call site). Move everything there too. Author: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAH2-Wzm7f+A6ej650gi_ifTgbhsadVW5cujAL3punpupHff5Yg@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/b0f7425ec2445678f32381de8bd3174d3cc2167e Modified Files -------------- src/backend/access/heap/pruneheap.c | 44 +++++++++++++++++++++++------------- src/backend/access/heap/vacuumlazy.c | 3 ++- src/include/access/heapam.h | 2 +- 3 files changed, 31 insertions(+), 18 deletions(-)