What is modification, and why do we care? (was Re: [Zope3-dev] Missing ObjectContentModifiedEvent)

[Dieter Maurer]

Jim Fulton wrote at 2005-5-26 14:43 -0400:
> ...
>   Probably the indexes that we *most* want to avoid reindexing are
>   text indexes.  We have a ISearchableText interface that we
>   commonly adapt objects to to get the text to index.  We really
>   can't predict how this text is computed.

Then, we probably do something wrong...

> ...
>   A safer strategy seems to me to be to have the indexes themselves
>   responsible for detecting changes that they care about.  I'm
>   pretty sure that some of the Zope 2 indexes are careful to avoid
>   reindexing, or at least avoid updating indexes if indexed values
>   haven't changed.

Even computing the value for a text index (without any change
to the index itself) can be very expensive: it may
include expensive fetching of a large object,
an expensive conversion (text extraction), expensive splitting
and comparison to what is currently indexes.

I would not like this overhead for e.g. workflow state changes by
default.

-- 
Dieter