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From Alessandro Benedetti <abenede...@apache.org>
Subject Re: Is it safe to upgrade an existing field to docvalues?
Date Wed, 24 Aug 2016 14:14:35 GMT
I am sorry Ronald but :
"  ask because my presupposition has been that we could turn it on without
any harm as we incrementally converted our indexes."

This is not possible, if you change the schema and then slowly update the
documents you are introducing inconsistency that will reflect in sorting
and faceting.
Because solr will check the field attributes, will see docValues, but then
will find only partial docValues.
So the docValue for some documents will be null.

You need to go live one-shot.
This is the reason Shawn and Toke suggest a parallel index, with the
docValues enabled and finally you swap.

Cheers

On Wed, Aug 24, 2016 at 2:56 PM, Shawn Heisey <apache@elyograg.org> wrote:

> On 8/23/2016 2:01 PM, Ronald Wood wrote:
> > In general, is there a way to migrate existing indexes (we have
> petabytes of data) by enabling docvalues and incrementally re-indexing? We
> expect the latter would take a month using an atomic update process.
>
> One way to handle it is to build a new index with an updated
> configuration, then switch to the new index.  Since you're not running
> SolrCloud, you can switch by swapping the cores.  If you were running
> SolrCloud, you'd need to alias the old name to the new collection, which
> might involve deleting the old collection first.  Swapping cores in
> cloud mode will break things.
>
> The other replies you've gotten are interesting.  The approach using
> Atomic Updates will only work if your index meets the requirements for
> Atomic Updates.
>
> https://wiki.apache.org/solr/Atomic_Updates#Caveats_and_Limitations
>
> You've already said it would take a month using atomic update ... which
> might mean you've already thought about whether or not your index meets
> the requirements.
>
> Toke's tool looks quite interesting, and would probably do the job a lot
> faster than any other method.
>
> Thanks,
> Shawn
>
>


-- 
--------------------------

Benedetti Alessandro
Visiting card : http://about.me/alessandro_benedetti

"Tyger, tyger burning bright
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?"

William Blake - Songs of Experience -1794 England

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