On Fri, 19 Feb 2010, Tom Lane wrote:
Teodor Sigaev <teo...@sigaev.ru> writes:
I found something strange with merge join. Let there are two table
Sorry, postgresql's version is 8.4 from today CVS
Can't reproduce it here, either in HEAD or 8.4. Sure you have a clean
build with no local modifications? The outright-incorrect last plan
you show seems to indicate something rather badly wrong with pathkey
matching.
I reproduced on my machine
PostgreSQL 8.4.2 on x86_64-unknown-linux-gnu, compiled by GCC gcc (Ubuntu
4.4.1-4ubuntu9) 4.4.1, 64-bit
Notice, plan is different and index scan on t1 uses wrong index.
Merge Join (cost=45224.01..251225.22 rows=9760080 width=86) (actual
time=1687.545..1687.545 rows=0 loops=1)
Merge Cond: ((t2.f1 = t1.f1) AND (t2.f2 = t1.f2) AND (t2.f3 = t1.f3) AND
(t2.f4 = t1.f4))
-> Index Scan using i2 on t2 (cost=0.00..65.44 rows=600 width=59) (actual
time=0.008..0.179 rows=600 loops=1)
-> Sort (cost=45224.01..45811.10 rows=234839 width=69) (actual
time=1612.586..1645.436 rows=161842 loops=1)
Sort Key: t1.f1, t1.f2, t1.f3, t1.f4
Sort Method: external sort Disk: 20888kB
-> Index Scan using i11 on t1 (cost=0.00..24274.83 rows=234839
width=69) (actual time=0.637..137.659 rows=234839 loops=1)
Total runtime: 1969.029 ms
(8 rows)
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: o...@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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