Solr transformer Peformance : [child] vs [subquery]

[Harshit Pandey <ha...@gmail.com>]

<https://stackoverflow.com/posts/64661000/timeline>

Hi Solr users

While reading through the solr docs
<https://lucene.apache.org/solr/guide/6_6/transforming-result-documents.html#TransformingResultDocuments-_subquery_>,
it states '*[subquery] is an improvement over [child]'*.

On deep diving through the docs 1,* [subquery] definitely *seems better
wrt. the capabilities/offerings (sorting of nested documents, etc). It
gives much more control as compared to the *[child]* transformer

*But is it better (or equivalent)  in terms of performance as well ?*

1 of the requirements of my current project is to sort the child documents
for every parent. *[child]* doesn't seem to have that support. *[subquery]* has
it, but I am hesitant to migrate to it as it seems to be more expensive.

As per my understanding, *[child]* only gets executed within the boundaries
of the child docs for a given parent. Whereas *[subquery]* gets executed
across the index. Hence the [*Subquery]* transformer seems to be more
expensive than [*Child].* Please help in validating this hypothesis.


"*Can I use the [subquery] transformer as efficiently as
the [child] transformer itself ???*"


Any details/insights wrt the performance comparisons will be appreciated.


Thanks,

Harshit

Re: Solr transformer Peformance : [child] vs [subquery]

[Harshit Pandey <ha...@gmail.com>]

Bump..

On Tue, Jun 8, 2021, 11:16 PM Harshit Pandey <ha...@gmail.com>
wrote:

>
> <https://stackoverflow.com/posts/64661000/timeline>
>
> Hi Solr users
>
> While reading through the solr docs
> <https://lucene.apache.org/solr/guide/6_6/transforming-result-documents.html#TransformingResultDocuments-_subquery_>,
> it states '*[subquery] is an improvement over [child]'*.
>
> On deep diving through the docs 1,* [subquery] definitely *seems better
> wrt. the capabilities/offerings (sorting of nested documents, etc). It
> gives much more control as compared to the *[child]* transformer
>
> *But is it better (or equivalent)  in terms of performance as well ?*
>
> 1 of the requirements of my current project is to sort the child documents
> for every parent. *[child]* doesn't seem to have that support.
> *[subquery]* has it, but I am hesitant to migrate to it as it seems to be
> more expensive.
>
> As per my understanding, *[child]* only gets executed within the
> boundaries of the child docs for a given parent. Whereas *[subquery]* gets
> executed across the index. Hence the [*Subquery]* transformer seems to be
> more expensive than [*Child].* Please help in validating this hypothesis.
>
>
> "*Can I use the [subquery] transformer as efficiently as
> the [child] transformer itself ???*"
>
>
> Any details/insights wrt the performance comparisons will be appreciated.
>
>
> Thanks,
>
> Harshit
>
>
>
>