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From Christopher <>
Subject Re: multi-table isolated batch scanner
Date Mon, 15 Apr 2013 20:13:37 GMT

It seems like you're talking about two features at once:
1) Multi-table batch scanner.
2) Scan Isolation on batch scanners like we have on regular scanners.
Is that correct?

I can see the utility of a multi-table batch scanner, but I haven't
seen a compelling need for implementing isolation on the
batch-scanners. Do you have a use case in mind for that?

Also, it seems that your use case for isolation is not so much the
isolated reads, but the statefulness of the iterator stack on the
server side. Is this correct? If so, I'm even more curious about your
use case for this, since that statefulness is only guaranteed per-row.

Christopher L Tubbs II

On Mon, Apr 15, 2013 at 3:10 PM, Adam Fuchs <> wrote:
> Thanks Bill,
> I care about latency and throughput. First available result ordering is
> fine, though.
> Does Guava just chain through a collection of iterators, completing one
> then moving to the next?
> Adam
> On Mon, Apr 15, 2013 at 3:06 PM, William Slacum <
>> wrote:
>> How are you expecting to get results back? Guava's Iterables could concat a
>> bunch of a Scanners together, if you didn't care about the throughput
>> aspect of it and simply wanted results from multiple tables.
>> On Mon, Apr 15, 2013 at 3:00 PM, Adam Fuchs <> wrote:
>> > Is anyone else pining for a multi-table isolated batch scanner, or is it
>> > just me? I like the automatic parallelism and balancing of the batch
>> > scanner, but I'm looking to maintain server-side state in my iterators
>> over
>> > long-running scans. I would also like to scan over multiple tables
>> > concurrently. Has anyone tried hacking something together with a pool of
>> > non-batch scanners?
>> >
>> > Adam
>> >

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