Versioning of Events and replay of projections

[Lars Baldes]

Hi,

I have a proble understanding how to verison my events propery. For every aggregate i have a separate event stream with an own version sequence.

If i take down a projection (statistics db) for maintenance and after restart I want to get the latest events (even events of aggregates that did not exist prior to the maintenance), ho do i implement that.

The only solution i found so far is a global sequence number over all events so the projection can ask for all events with the global sequence number higher than the last received version in my projection.

I think this solution would lead to performace issues in the write model as I can only write single threaded to the event stream to ensure there are no duplicates of the global sequence number.

Is there a more elegant way to achieve this?

Thanks in advance 

Lars

[Greg Young]

ES handles this and can easily write 10,000s of events/second. If using a sql based store just use an identity column or a sequence. There is no issue if the sequence is sparse.

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