Bug 6789: biblios with many items can result in broken search results link

Bug 6789: biblios with many items can result in broken search results link

This patch fixes an issue whereby biblios with many items (often > 500) would index,
but not the biblionumber itself, resulting in search results with a) inaccurate item counts
and b) no biblionumber to use in the link to the details page.  This is due to Net::Z3950::ZOOM  not providing
a mechanism for specifying different connection attributes; the maximumRecordSize ZOOM connection attribute,
if not specified, defaults to 1MB, which is less than the size of a MARC record with many, many 952 fields.  Since
it is unlikely we can fix Net::Z3950::ZOOM in a timely fashion, this patch aims to build a workaround on the Koha end.

This patch changes EmbedItemsInMarcBiblio to use append_fields instead of insert_ordered_fields,
so the 999$c will come before the item records.  It's VERY unlikely we will encounter more than 1MB of biblio-level MARC
content, as this would break the ISO-2709 standard by a large factor.

To this end, it also moves the fix_biblio_ids portion of get_corrected_marc_record out of rebuild_zebra.pl,
and makes it a part of GetMarcBiblio (right before EmbedItemsInMarcBiblio, so the 952s still come last).  fix_biblio_ids
is kept as a subroutine for the deletion portion of rebuild_zebra.pl, which still uses it.

It also uses the subroutine parameter in GetMarcBiblio to do the EmbedItemsInMarcBiblio action, rather than having
rebuild_zebra.pl perform it on the itemless record returned from GetMarcBiblio.  Simpler and cleaner that way.

To verify bug issue:
1. Find a biblio with over 700 items (or enough that the resulting MARCXML is greater than 1MB)
2. search for this biblio (in a search that would return multiple results, not just this title).  You should get the title in
the results list
3. attempt to click the link to this biblio's details page; the biblionumber should be blank, leading to a 404

To test solution:
1. Apply patch
2. modify the biblio slightly (click the 005 for example) and save
   OR manually add the biblio to zebraqueue for reindexing
3. after rebuild_zebra.pl -z -b -x runs, use the same search as above. The title should still appear.
4. click the link, and find yourself on the biblio detail page as desired

Signed-off-by: D Ruth Bavousett <ruth@bywatersolutions.com>
Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>