How to know during Table rebalance which epoch no is using?
Hi All,
I have to do a table re-balance in my cluster and is huge table and taking a lot of time .We did all the Vertica best practices and didn't help.
Can i know from which epoch number the refresh gets starts for that table.My plan is i will start the re-balance for that table in off hours and after some time i will cancel the re-balance as the business hour starts and till that time time it must have advanced with some epoch number.On the next day off hours when i start the re-balance again for that table it should start the epoch no where it stopped.With that approach we can complete the re-balance.
Let me know if this is possible,I didn't see any where for the re-balance which epoch no it starts with.
thanks
Best Answer
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Vertica_Curtis
Employee
Rebalance? A rebalance isn't tied to an epoch. You would issue a rebalance_table() if it's not aligned evenly on all the nodes in your cluster. Is that the case? A table rebalance will distribute all the table's data across all the nodes per the segmentation clause of the projection definitions.
But I see your also using the word refresh here, which means to distribute the data from a super projection to a new projection on a table. So, if I have a table, with a projection, and I built a new table, I will need to refresh that projection in order for it to be used. That's also not tied to an epoch, since it's just all data in that table. If you cancel either of these operations, it's just going to roll back internally so you'll lose all that work. I'm not aware of a way to do a refresh incrementally. refresh has it's own resource pool - you could just lower the priority of that pool so that it doesn't really disturb anything. Assuming a refresh is what you're trying to accomplish here, and not an actual rebalance.
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