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Tom Lane 3d351d916b Redefine pg_class.reltuples to be -1 before the first VACUUM or ANALYZE. ... Historically, we've considered the state with relpages and reltuples both zero as indicating that we do not know the table's tuple density. This is problematic because it's impossible to distinguish "never yet vacuumed" from "vacuumed and seen to be empty". In particular, a user cannot use VACUUM or ANALYZE to override the planner's normal heuristic that an empty table should not be believed to be empty because it is probably about to get populated. That heuristic is a good safety measure, so I don't care to abandon it, but there should be a way to override it if the table is indeed intended to stay empty. Hence, represent the initial state of ignorance by setting reltuples to -1 (relpages is still set to zero), and apply the minimum-ten-pages heuristic only when reltuples is still -1. If the table is empty, VACUUM or ANALYZE (but not CREATE INDEX) will override that to reltuples = relpages = 0, and then we'll plan on that basis. This requires a bunch of fiddly little changes, but we can get rid of some ugly kluges that were formerly needed to maintain the old definition. One notable point is that FDWs' GetForeignRelSize methods will see baserel->tuples = -1 when no ANALYZE has been done on the foreign table. That seems like a net improvement, since those methods were formerly also in the dark about what baserel->tuples = 0 really meant. Still, it is an API change. I bumped catversion because code predating this change would get confused by seeing reltuples = -1. Discussion: https://postgr.es/m/F02298E0-6EF4-49A1-BCB6-C484794D9ACC@thebuild.com		5 years ago
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Makefile	Split all OBJS style lines in makefiles into one-line-per-entry style.	6 years ago
appendinfo.c	Reconsider the representation of join alias Vars.	6 years ago
clauses.c	Suppress unnecessary RelabelType nodes in yet more cases.	5 years ago
inherit.c	Allow partitionwise joins in more cases.	6 years ago
joininfo.c	Update copyrights for 2020	6 years ago
orclauses.c	Update copyrights for 2020	6 years ago
paramassign.c	Reconsider the representation of join alias Vars.	6 years ago
pathnode.c	Add hash_mem_multiplier GUC.	6 years ago
placeholder.c	Update copyrights for 2020	6 years ago
plancat.c	Redefine pg_class.reltuples to be -1 before the first VACUUM or ANALYZE.	5 years ago
predtest.c	Update copyrights for 2020	6 years ago
relnode.c	Remove unnecessary #include.	6 years ago
restrictinfo.c	Update copyrights for 2020	6 years ago
tlist.c	Update copyrights for 2020	6 years ago
var.c	Update copyrights for 2020	6 years ago