gistfile1.txt

randgalt1
Greetings C* people
I have a table that I need a secondary index for. I need to be able to search via a hash. So, high cardinality. I understand that that's not considered best practice for a C* secondary index. What are the pros/cons? Performance isn't really a concern with this.
Alternatively I could manage my own lookup table but that would be a lot more work
1:06
hanine [[email protected]] entered the room.

1:06
rcoli
in general secondary indexes sorta suck unless you really need the atomic update property

1:06
thobbs
well, if performance isn't a concern, you can use them

1:06
rcoli
but if you're motivated to save the other work...

1:07
thobbs
but it's going to be ~100x more expensive than querying your own lookup table

1:07
rcoli
^^^

1:07
randgalt1
100x - really? Wow. That is a consideration
1:07
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1:07
thobbs
yup, it's a scatter-gather operation, basically

1:07
randgalt1
Hmm - let me rethink
1:08
jeffj
randgalt1: each node indexes content on that node, so if you dont have a partition key in the WHERE clause, it probably asks every node
1:09
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1:09
rcoli
(so you pay more in an absolute sense when you have more nodes...)

1:09
jeffj
is it really 100x though? it's all in parallel, but it is asking all N nodes instead of (probably 2-3)

1:09
rcoli
(which is not usually how horizontal scalability works)

1:09
randgalt1
Thanks folks - you've convinced me

1:09
jeffj
if you only have 10 nodes, it's probably not a big hit.

1:09
rcoli
jeffj: it's asking all N
oh, sorry, mis-parsed
1:09
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1:09
jeffj
rcoli: <3

1:09
rcoli
it is vs is it

1:09
thobbs
jeffj: yeah, not necessarily 100x latency due to parallel requests
but the overhead in terms of processing, etc is probably 100x

1:10
jeffj
also if N is only 3-4x RF, then it's only 3-4x
1:10
jeffj
randgalt1: how many nodes in your cluster?

1:10
randgalt1
We don't know yet. But, I'd prefer to not have to worry about that. It's not a big deal to write my own lookup table
1:10
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1:11
jeffj
1:11
ah, ok. do that then :D that's what most of us do