SQL Server - unpredicatable log growth

Asked By Gurmit on 25-Sep-09 11:48 AM
it happened only once on a business warehouse database where log fills up
80GB disk space in few minutes. database is in simple recovery model. Is
there any way to find out what may have caused it? long running/slow queries?

Russell Fields replied on 25-Sep-09 12:28 PM
A transaction log, even in simple recovery model, cannot reuse any space
before the oldest open transaction.   So, if a transaction had made even a
small update and was still open, all subsequent updates would remain in the
transaction log until the oldest transaction either committed or rolled

Still 80GB in a few minutes is quite extreme. It makes me think that some
process tried to update every row of some very large table in a single
statement. (Such as might happen when adding a column with a default value.)