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Date: Wed, 06 Nov 2013 14:08:58 -0800
From: Dan Gould <dan@chill.com>
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To: user@cassandra.apache.org
Subject: CQL 'IN' predicate
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I was wondering if anyone had a sense of performance/best practices
around the 'IN' predicate.

I have a list of up to potentially ~30k keys that I want to look up in a
table (typically queries will have <500, but I worry about the long tail).  Most
of them will not exist in the table, but, say, about 10-20% will.

Would it be best to do:

1) SELECT fields FROM table WHERE id in (uuid1, uuid2, ...... uuid30000);

2) Split into smaller batches--
for group_of_100 in all_30000:
    // ** Issue in parallel or block after each one??
    SELECT fields FROM table WHERE id in (group_of_100 uuids);

3) Something else?

My guess is that (1) is fine and that the only worry is too much data returned (which won't be a problem in this case), but I wanted to check that it's not a C* anti-pattern before.

[Conversely, is a batch insert with up to 30k items ok?]

Thanks,
Dan