Increasing bib library last-doc-number

• Article Type: General
• Product: Aleph
• Product Version: 18.01

Description:
We would like to increase the bib library util g/2 last-doc-number from the current value of 1500000 (1.5 million) to a value such as 20000000 (20 million) in order to have a distinct sequence for the records added from this point on. Is there any reason not to do this?

Resolution:
In most cases (patron record numbers, order numbers, budget numbers, etc.) the length of the number doesn't especially matter. But in the case of doc records (bib, authority, etc.) which have indexes built on them, it does.

Most of the indexing jobs create a cycles file, typically with 50,000 records in each cycle. A cycle will be created for each 50,000 records even if there are no records in that range. Large gaps can make the cycles file unwieldy. And certain steps which have no records to process may get error messages at certain points (-- though the jobs handle this and continue normally).

The main disadvantage to large gaps is in the Words files. The Word programs create a bit-map with one position for each document number. This is stored in the z98 in a compressed form, but, of course, needs to be uncompressed at different points. It then takes a lot more space than it would otherwise.

Thus, we recommend against having large gaps in doc numbers (say, bigger than a million) -- especially in the cases where the library is Word-indexed.

Note: in the case of an ADM library which does not have indexes you may want to increase the ADM library last-doc-number in order to allow the bib and ADM numbers to stay in synch. This is described in SKB 8192-667.

• Article last edited: 10/8/2013