Merlin Moncure wrote:
It certainly makes quite a difference as I measure it:
doing select(1) from a 181000 page table (completely uncached) on my
PIII:
8.0 : 32 s
8.1 : 25 s
Note that the 'fastcount()' function takes 21 s in both cases - so all
the improvement seems to be from the count overhead reduction.
Are you running windows? There is a big performance improvement in
count(*) on pg 8.0->8.1 on win32 that is not relevant to this debate...
No - FreeBSD 6.0 on a dual PIII 1 Ghz. The slow cpu means that the 8.1
improvements are very noticeable!
A point of interest - applying Niels palloc - avoiding changes to
NodeAgg.c and int8.c in 8.0 changes those results to:
8.0 + palloc avoiding patch : 27 s
(I am guessing the remaining 2 s could be shaved off if I backported
8.1's virtual tuples - however that looked like a lot of work)
Cheers
Mark
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
