On Wed, 17 Nov 2004, Achilleus Mantzios wrote:
O Oleg Bartunov ?????? ???? Nov 17, 2004 :
Gary,
if you need really fast solution for you task and dont't afraid
non-standard soltion, take a look on contrib/ltree module.
http://www.sai.msu.su/~megera/postgres/gist/ltree/
Oleg
Oleg how would you compare an ltree solution against a
genealogical approach using intarray??
i.e. store for each node, its path to root,
e.g. path='{4,2,7}'::int4[] where 4 is the id of the father,
2 of the grandfather, and 7 of the root, whereas root has
path is null.
That way we can do really fast queries using ~, have indexes
on level (path length),first (immediate ancestor),last (root)
using C functions that we can easily write and so forth.
I have extensively used this approach with success.
Can you comment on the pros and cons of each? (int[] with intarray vs
ltree).
well, internally both approaches are very much the same :)
if you don't need ltree features like human readable path
But I'd like to have some real numbers. Could you spent some time and
create test suite and compare genealogical approach and ltree ?
I'll add resuts to docs.
Thanx
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: [EMAIL PROTECTED], http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83
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Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: [EMAIL PROTECTED], http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83
---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
