[OPEN-ILS-DEV] Re: Serials Schema Proposal - Further De-emphasis of MARC as Record Format

[Dan Wells]

Hello Mike,

Thanks for the detailed reply.  It helps to know we are still not on the same page :)  

First, I want to be clear about what the serial.caption_and_pattern table actually contains (in my mind).  The confusion seems to have been brought about by my hastily naming a column 'marc' in my original email despite the fact that it doesn't contain any actual MARC, just most of the data which the field would contain.  I am renaming it 'pattern_code' for clarity.  Here is a pseudo-db representation of an example:

row-of-serial.caption_and_pattern [
  id: 1 
  type: basic
  active: t
  enum_1: 'v.'
  enum_2: 'no.'
  enum_3: 'pt.'
  enum_4: null
  enum_5: null
  enum_6: null
  chron_1: '(year)'
  chron_2: '(month)'
  chron_3: '(day)'
  chron_4: null
  chron_5: null
  pattern_code: "['2','0','a','v.','b','no.','u','12','v','r','c','pt.','u','3','i','(year)','j','(month)','k','(day)','w','j']"
]

I have some good ideas of how to create an editor for such rows, and it won't be a straight MARC editor.  We could also trim down some minor redundancy in 'pattern_code', but I don't think it's worth the trouble on either end.

We all understand that reliance on MARC formatted data in general is frail, but in my experience working through this, here are some more specific reasons to get away from it here:

1. Once a caption/pattern is created, it should be *immutable*.  Changing it would redefine the meaning of any attached holding statements, and we don't want that.  If it actually changes, we always need to keep the old and create a new one.
2. (I should have answered this earlier) While pretty rarely seen (in my experience), it is possible for a serial to have two or more active patterns of the same type.  Most common will be serials which receive several different but regular supplements, such as a perhaps 'buyers guide' every December and maybe a 'trends' issue every June.  Even for the 'basic' type, one example I have seen is of a serial titled something like 'Oceanography' which might have issues subtitled 'Animal Life' in odd months and those subtitled 'Plant Life' in even months, and these might be held or bound separately.  Each unit type gets an active caption/pattern.  The entire MFHD standard (even the pattern portion) is designed around describing a snapshot of 'what we have' (the pattern exists for compression and expansion, not really prediction) rather than 'what will come', so it simply doesn't consider this problem.
3. MFHD is reliant upon 'link ids' to make sense of itself internally.  Duplicate link ids or deleting a field with a linked id will cause obvious trouble.

Based on these observations (and probably more I am not thinking of), I think keeping an ongoing link to a fully editable MFHD record for titles under 'serial control' is inviting disaster unnecessarily.  We could keep pointing to serial.record_entry for the other (non-MARC) DB fields, but I think we gain a lot of clarity, safety, and convenience if we deprecate it, allowing it to continue as an independant legacy/stop-gap solution.  This will become more important as the serial.serial table develops in ways not yet foreseen.

I hope this helps clarify my intentions with these new tables.  The overall goal is to be rid of storing MARC internally for serials under 'control', and certainly avoiding any direct editing of data at the MARC level.  Is this reasonable?  I think so!

Thanks again,
Dan