| From: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, Pål Stenslet <paal(dot)stenslet(at)exie(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Should Oracle outperform PostgreSQL on a complex |
| Date: | 2005-12-18 22:10:01 |
| Message-ID: | 43A5DE39.6080901@paradise.net.nz |
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| Thread: | |
| Lists: | pgsql-performance |
Simon Riggs wrote:
> On Sun, 2005-12-18 at 15:02 +1300, Mark Kirkwood wrote:
>
>
>>Yeah - the quoted method of "make a cartesian product of the dimensions
>>and then join to the fact all at once" is not actually used (as written)
>>in many implementations
>
>
> But it is used in some, which is why I mentioned it.
>
> I gave two implementations, that is just (1)
>
>
Sorry Simon, didn't mean to imply you shouldn't have mentioned it - was
merely opining about its effectiveness....
>>- probably for the reasons you are pointing out.
>>I found these two papers whilst browsing:
>>
>>
>>http://www.cs.brown.edu/courses/cs227/Papers/Indexing/O'NeilGraefe.pdf
>>http://www.dama.upc.edu/downloads/jaguilar-2005-4.pdf
>>
>>
>>They seem to be describing a more subtle method making use of join
>>indexes and bitmapped indexes.
>
>
> Which is the option (2) I described.
>
Ok - I misunderstood you on this one, and thought you were describing
the "star transformation" - upon re-reading, I see that yes, it's more
or less a description of the O'Neil Graefe method.
best wishes
Mark
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