The current closed timestamp interval is set to 30 seconds. This limit provides an upper bound on the duration of transactions which cannot be pushed. As far as I understand, there are some schema change operations which can be long running (potentially proportional to the size of the data which is being modified) and must currently observe their own timestamp (preventing pushes). In order to feel comfortable lowering this value, we need to ensure that the system does not create these un-pushable long-running transactions. I'm using this issue as a catch all to gather information about work required before we could consider lowering the value.

@dt could you help me identify which operations might currently fall in to that category so we can make a decision about whether this is a worthwhile goal?

cc @awoods187 @rolandcrosby