[Zope-dev] ZCatalog Indexes tab crawls...

[Dieter Maurer]

Chris Withers wrote at 2003-7-17 11:12 +0100:
 > Has anyone noticed that the ZCatalog Indexes tab crawls if you have loads of 
 > objects indexed.
 > 
 > My guess is that some types of index take way too long to figure out how many 
 > objects are indexed. Anyone know which index types those could be?

The one that provide the correct number of indexed objects
(rather than just the number of indexed terms).

Because the same object can be indexed under several terms,
determining the number of indexed objects requires to
build the union of all the index values. This almost surely
has quadratic (worst case) runtime characteristics.

 > BTW, would anyone object if I removed that object count, since it's not often 
 > very useful...

You probably should replace it with the size of the index (i.e.
the number of index terms).

Formerly, the index overview displayed this information but
under a buggy "# objects" title. Someone fixed this for most
indexes, they now show the number of objects but at a high
price.

I suggest to change the title to "# index terms" and
revert for the indexes to the old behaviour.


Others pointed out, that also the size determination for an
index may be expensive. However, it is at most linear in the number
(rather than quadratic) and all recently created indexes now
use "BTrees.Length" to maintain their size (which gives constant time).

Having a feeling how large an index is is valuable information.


Dieter