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Hello Maksym,

Thank you for your work!

I suggest you to consider more general approach and hide backend specific
staff. I have the next proposal:
1) add support for inconsistent write operation by adding PutItem,
UpdateItem and DeleteItem request parameters "consistent" = True of False
(as well as GetItem and Query requests)
2) add possibility to set backend specific metadata (it would be nice to
use some generic format like json) per table in scope of create table
request. I suggest to specify mapping for Cassandra consistency level per
operation type (consistent read, inconsistent read, consistent write,
inconsistent write)

I agree that now we have a limitation for inconsistent write operation on
tables with indexed fields and for requests with specified expected
conditions. I have thought about how to overcome this limitation and it
seems that I found out solution for index handling without CAS operation.
And maybe it is reasonable to redesign it a bit.

On Mon, Apr 28, 2014 at 8:33 AM, MAKSYM IARMAK (CS) <
Maksym_Iarmak at symantec.com> wrote:

>  Hi,
>
> Because of we can't use inconsistent write if we use indexed table and
> condition operations which indexes based on (this staff requires the state
> of data), we have one more issue.
>
> If we want to make write with consistency level ONE (WEAK) to the indexed
> table, we will have 2 variants:
> 1. Carry out the operation successfully and implicitly make write to the
> indexed table with minimally possible consistency level for it (QUORUM);
> 2. Raise an exception, that we can not perform this operation and list all
> possible CLs for this operation.
>
> I personally prefer the 2nd variant. So, does anybody have some objections
> or maybe another ideas?
>
>  ------------------------------
> *From:* MAKSYM IARMAK (CS) [Maksym_Iarmak at symantec.com]
> *Sent:* Friday, April 25, 2014 9:14 PM
> *To:* openstack-dev at lists.openstack.org
> *Subject:* [openstack-dev] [MagnetoDB] Configuring consistency draft of
> concept
>
>   >So, here is specification draft of concept.
>
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>
>


-- 
Best regards,
Dmitriy Ukhlov
Mirantis Inc.
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