Write confirmation from 1 slave in each DC (say 2 DC)

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dhsieh

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May 23, 2012, 6:41:45 PM5/23/12
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Assuming using Java Driver 2.8.0, wonder if there is a way to write
confirmation from 1 slave in each DC (say 2 DC). This is to ensure
that subsequent reads in each DC will get latest write copy with
slaveOk().

Eliot Horowitz

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May 23, 2012, 8:27:38 PM5/23/12
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Have you read this:
http://www.mongodb.org/display/DOCS/Data+Center+Awareness
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dhsieh

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May 23, 2012, 9:17:12 PM5/23/12
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Yes, but what's not clear is if slaveOk read (assuming java driver
v2.8.0) will guarantee returning latest copy from the local DC tagged
slave node. Even that's the case, won't it cause local calls directed
to that tagged slave node and thus causing unbalanced load, will it?

dhsieh

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May 23, 2012, 10:14:42 PM5/23/12
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To be specific, is there a read option to select from DC tagged slave
nodes in local DC?

dhsieh

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May 24, 2012, 3:45:03 PM5/24/12
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I see that Java Driver 2.8.0 contains an improvement:

[JAVA-474] - Support ReadPreference Tagging

I wonder if this is the feature that will address my need for this
posting?

Eliot Horowitz

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May 27, 2012, 12:59:49 PM5/27/12
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Yes - that is what you want.
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