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From Steve Robenalt <sroben...@highwire.org>
Subject Re: Large number of tombstones without delete or update
Date Thu, 24 Mar 2016 01:08:37 GMT
Hi Henry,

Since new values are written without checking for previous values, the only
way to assure that a nulled column blocks a previously valid one is to
write a tombstone to occlude whatever value might have been present. I
believe there are some recent changes as to the handling of null values to
relax some of this behavior under some circumstances, but I'm not sure as
to which version it affects or what the circumstances are. A similar
question was raised recently on this list, so the list archives may be of
some use.

Steve


On Wed, Mar 23, 2016 at 6:00 PM, Henry M <henrymanmail@gmail.com> wrote:

> What is the reason for the tombstone for a brand new insert? Do the fields
> get written as a whole (both nulls and non-nulls?
>
> I understand the rationale for tombstones for deletes and updates but it
> does not make sense for an insert (I am trying to make sense of it). I
> understand Cassandra writes the record without first checking its existence
> but wouldn't the whole set of fields including values to null out be
> applied as one single operation?
>
> Thank you,
> Henry
>
>
>
> On Wed, Mar 23, 2016 at 5:47 PM, Eric Stevens <mightye@gmail.com> wrote:
>
>> In addition to writing null values acting as tombstones, also INSERTing a
>> collection (or UPDATE where you set the collection rather than append to
>> it) are also operations which will create tombstones.
>>
>> On Wed, Mar 23, 2016 at 12:09 PM Robert Coli <rcoli@eventbrite.com>
>> wrote:
>>
>>> On Wed, Mar 23, 2016 at 9:50 AM, Ralf Steppacher <ralf.vivates@gmail.com
>>> > wrote:
>>>
>>>> How come I end up with that large a number of tombstones?
>>>>
>>>
>>> Are you inserting NULLs?
>>>
>>> =Rob
>>>
>>>
>>
>


-- 
Steve Robenalt
Software Architect
srobenalt@highwire.org <bzavon@highwire.org>
(office/cell): 916-505-1785

HighWire Press, Inc.
425 Broadway St, Redwood City, CA 94063
www.highwire.org

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