[OPEN-ILS-DEV] config.global_flag cat.bib.use_id_for_tcn

[Martha Driscoll]

Alan,
For NOBLE's migration, I did set cat.bib.use_id_for_tcn to false.  I 
loaded our legacy system's id number into the tcn_value just for the 
purpose of linking items, circulations etc.  Since our legacy system 
id's all begin with a letter, there is no danger of a duplicate 
happening later.  I did set the flag back to true immediately after 
migration.

Even though all my scripts based matching on the tcn_value, right before 
migration I decided to use the legacy bib id (without the leading 
character and check digit) as the evergreen biblio.record_entry.id. 
This would have allowed me to match things a little easier, but I mainly 
did it so we could edit lots of links in online booklists to turn them 
into evergreen links.

I also used the legacy id number for user and copy id's.  This made 
matching up circs and holds quite straightforward and therefore less 
error prone.  I am so glad the original id's were preserved in 
Evergreen.  It makes it easy to look up the record in the legacy system 
when a problem gets reported.

The legacy id numbers are all sequential numbers, so updating the last 
value in the appropriate sequence for the table ensures that duplicates 
won't happen later.  For example, after loading copies and setting the 
copy.id to the original legacy system id, I updated the copy_id_seq:

SELECT SETVAL('asset.copy_id_seq', (SELECT MAX(id) FROM asset.copy));

I have noticed that bib records that are edited or overlaid have their 
database id replace the original tcn_value.  This is because of the 
cat.bib.use_id_for_tcn being set back to true after migration.  This 
destroys the legacy id that was put there, but not a problem for us 
because we put the legacy id in the biblio.record_entry.id.

-- 
Martha Driscoll
Systems Manager
North of Boston Library Exchange
Danvers, Massachusetts
www.noblenet.org

On 6/14/2012 3:15 PM, Alan Rykhus wrote:
> Hello,
>
> I had a question about the config.global_flag cat.bib.use_id_for_tcn
> setting.
>
> I was working on a migration and was having issues because of this. I
> was planning on using the tcn_value for linking purposes later on as I
> had in a previous conversion. I put the a number in here from the old
> system that helps me find the bib and link items, loans, holds, etc. to
> the bib.
>
> 1. What ramifications will we have if we set this flag to false?
>
> 2. What happens if we then set it to true after we are done with the
> migration? I can see where the actual biblio.record_entry.id will
> eventually become the same value as migrated
> biblio.record_entry.tcn_value entries and there would be duplicates.
> Will this be a problem?
>
> I see there are a couple of bug reports on this(really 1, the second is
> a duplicate). But I did not find anything referring to the functionality
> this flag is trying to accomplish.
>
> thanks -- al