[Erp5-users] Performance of ZSQLCatalog

[Jean-Paul Smets]

Le Mercredi 12 Janvier 2005 01:28, Wolfgang Keller a écrit :
> Hello,
>
> recently I happened to read the story about ERP5 at
> http://www.pythonology.org/success&story=nexedi and got astound by the
> performance claims for ZSQLCatalog there: "a Zope database with more than
> 2,000,000 objects can be queried with statistical methods in a few
> milliseconds"

yes, this is right. 

>
> Knowing that "a few milliseconds" will be barely enough for even a fast
> harddisk to move its head to a given cylinder, how is this supposed to
> work? I would guess that the above claim can only be realised for
> databases where the entire "Catalog" fits in RAM, right?

mysql for example optimises itself and caches many things into RAM (as Linux 
does for fs). With the right indices, this performance can be obtained.

to be more precise, depending on the kind of stat, the performance can be 
from a few milliseconds (sql index allows to retrieve a few lines) to a few 
seconds (stats on a join of 10K x 10K x 10K lines) to a few minutes (badly 
optimised SQL query).

JPS.


> TIA,
>
> Best regards
>
> Wolfgang Keller
>
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