[Zope-dev] RE: [ZC] 365/ 2 Reject "metadata in Catalog is space inefficient"

[Toby Dickenson]

On Fri, 26 Apr 2002 09:02:26 +1000, "Jay, Dylan" <djay@avaya.com>
wrote:

>I specifically stated a FieldIndex, not TextIndex. It is a special case,=
=20

Yes. KeywordIndex too, although you lose ordering information.

>but
>when your talking a huge Catalog this could be a lot of extra data.

Under your proposal data would be stored two times (original object,
plus index) rather than three times (metadata too). A saving of 2:3,
assuming the original object is no larger than the sum of its indexed
properties. In most cases the original object is bigger, and it will
probably add up to no more than a few percent of disk space.

Are there any common scenarios where the margin would be bigger?

Note that this scheme may not necessarily give runtime performance
benefits. Loading the reverse index data may not be any faster than
loading metadata.



Toby Dickenson
tdickenson@geminidataloggers.com