How can one rollover a sequence back to zero after you delete records from a table with one such sequence. I see it starting with the last value of the sequence inserted.
On 7/11/07, Tom Allison <[EMAIL PROTECTED]> wrote:
On Jul 10, 2007, at 3:09 PM, Tom Lane wrote: > > "Harpreet Dhaliwal" <[EMAIL PROTECTED]> writes: >> Transaction 1 started, saw max(dig_id) = 30 and inserted new >> dig_id=31. >> Now the time when Transaction 2 started and read max(dig_id) it >> was still 30 >> and by the time it tried to insert 31, 31 was already inserted by >> Transaction 1 and hence the unique key constraint error. > > This is exactly why you're recommended to use sequences (ie serial > columns) for generating IDs. Taking max()+1 does not work, unless > you're willing to lock the whole table and throw away vast amounts of > concurrency. I wonder how SQL server is handling this? Are they locking the table? I realize it's off-topic, but I'm still curious. Sequences are your friend. they come in INT and BIGINT flavors, but BIGINT is a lot of rows. Can set set Sequences to automatically rollover back to zero?
