Re: INFORMIX & DATA TYPE SERIAL: Questions

sujata_soman_at_omm-la2-infotech-001@internet.omm.com wrote: > Hi all, > Some questions on how Informix handles the "Serial(n)" data type. > 1. How is the "next serial number" calculated ? why do I sometimes see different > behaviour(s), for eg, if we have 5 rows, numbered 1 thru 5, and I delete #5, and > insert a new row :- On some occasions, the new serial number is #5, and on > others, it is #6 - Why ? I've never seen this the next record added should always be 6 unless the record allocated serial number 5 was rolled back and no other row was added to the table between the rollback and the new insert. > 2. I once deleted all the rows in a table with a serial number field, and when I > tried to insert new rows, the serial number had not been updated to 0, ie the > new numbers picked up from the old set. Correct. You can use ALTER TABLE to reset the serial number. > 3. Now, when you create a new table with a serial type column, if you do not > specify an initial number ( for eg serial(2) vs serial ), does that default to > 0 ?? Exactly, new tables with serial type columns default to zero (0). > 4. Are the "holes" in a serial type column ever filled/re-used ?? Not by the automatically generated values, though you can insert rows with explicit serial numbers and use these 'holes'. Art S. Kagel