Re:Snappy Dashboards with Redis
by mbell on Monday October 15, 2012 @08:48PM
(#4657875)
The article said they could rebuild the count if they needed to. So something in regards to each click is being stored. If you were using postgres you'd just setup a trigger on that table to increment the click values (stored in another table) as appropriate. No aggregate function needed.
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Certainly you can implement this same pattern without Redis. Triggers in Postgres would be a reasonable way to do it. I didn't say you can't do this in Postgres, I said you can't do it with COUNT().
It does indeed sound like they're storing every click: that's precisely why using aggregate functions would be expensive.
Re:Snappy Dashboards with Redis
by guywithabike on Monday October 15, 2012 @10:02PM
(#4658124)
You absolutely can do it without COUNT. Just increment a counter value, the same way they're doing it in Redis.
Why was this downvoted? Adding 1 to any number field is just as an atomic operation as incrementation is in Redis.
Presumably it was downvoted (not by me) because it's refuting a claim I didn't make:
samstokes: I said you can't do it with COUNT()
guywithabike: You absolutely can do it without COUNT
Then we agree.