Re: [Koha-zebra] Re: [Koha-devel] playing with the zebra on cvs head

[Thomas D]

If you were only using the leader, 000, that may be relatively trivial. 
However, even using 000 involves evaluating multiple values from positions
06 and 07 to determine whether printed material is a book or a serial.  I
was working on some little Perl code a week or so ago to partially
demonstrate the media type issue for your question from MARC 21
bibliographic 000/06 /07 into 008, 006, 007, 245 $h $k, 300 $a $b $c $e
depending upon the availability of the fields and subfields and how they are
populated.  The UNIMARC equivalent would be 000/06 /07, 100, 105-140, 200
$b, and 215.  The issue is ultimately much too complex for a simple test
against indexes across all relevant fields and subfields at query time.

The media type issue becomes complex very quickly unless you only ever had
one mechanised cataloguer creating all original records in a uniform manner,
and then the issue would be a little less complex.  I had an abbreviated
idealised mapping for media type stored in Zope a year ago but that was
really noting more than abbreviated and idealised. way of representing that
information in some perfect record and not adequate for evaluating the
diversity of real world records.

The only solution I would see for what we would seem to want to do for media
type is to evaluate the media type from all relevant fields and store a
standardised set of valuations in a local use field.  Media type consists of
a complex set of data and would seem to require at least one entire local
use field all to itself.  Without absolute uniformity in record creation,
there is no certainty about the degree of media type specificity contained
in any large set of records.  The general material designation should be
resolvable but the special material designation may not be at various levels
for many large sets of records.  Too many of the media type elements are
optional, and likely to be unused in common cataloguing practise.  Some
elements are found in fields that are not exceptionally old and therefore
cannot be relied upon for being available in older records.  For example,
you may know that any record is for cartographic material or not, but
knowing the type of cartographic material beyond that may be uncertain for
all records.

This is MARC, if you think something is simple; then you have not looked
closely enough, considered carefully enough, or examined a sufficiently
diverse set of records.  MARC is too complex for many purposes and not
thorough enough for some desirable purposes.

The question then becomes will Zebra index any arbitrary set of data chosen
for use in local use fields for retrieving in a precise manner?


Thomas D

Quoting Mike Taylor <address@hidden> :
> ---------------- Beginning of the original message ------------------
> 
> > Date: Thu, 18 Aug 2005 02:21:09 +0000
> > From: Mike Rylander <address@hidden>
> > 
> > Along these same lines, will the Zebra index be able to
> filter on
> > parts of the MARC record's fixed fields?  As an example, one
> of the
> > search requirements for Evergreen is to be able to limit a
> search to
> > just books or just video recordings (type of record), or
> even to
> > large print books (form of item).
> 
> Have no fear -- this won't be a problem.
> 
> No time to go into details now, but you can make plans on the
> assumption that this kind of thing will work just fine.
> 
>  _/|_ 
> ___________________________________________________________________
> /o ) \/  Mike Taylor  <address@hidden> 
> http://www.miketaylor.org.uk
> )_v__/\  "Politicians, ad agencies, and other liars are prone
> to using
>        high-sounding, low-content, prose to back their points. 
> Heck,
>        if people really understood what they were saying, they
> might
>        be in big trouble" -- Rheal Nadeau.
> 
> 
> 
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