Spans seem to have the problem of creating huge "List<Something>" during
query iteration to track some stuff. I never understood the code, but to
me it was always crazy to have Lists populated during execution. We
replaced all SpanQueries by Intervals in patent search and speed is much
faster and heap usage is tiny.
A span/phrase with inOrder=false can always replaced by a phrase with
slop. The slop is always without order, as it is an "edit distance" only
(see documentation). If you need in order, an interval is required.
Phrases are only in order for "slop=0". Compare to "slop=1" which means
"next to each other" and is no longer in order.
Uwe
Am 15.12.2022 um 16:44 schrieb Mikhail Khludnev:
Michael, thanks for stepping in!
> it seems that simple phrase
queries would suffice here in place of spanNear?
I think it wouldn't. It seems to me 4 is slop, and false is inOrder.
Sjoerd, can you comment about particualt span queries you uses?
Also, do you have any heap dump summary to confirm high memory
consumption by spans?
On Thu, Dec 15, 2022 at 5:33 PM Michael Gibney
<mich...@michaelgibney.net> wrote:
I don't think that nested boolean disjunctions consisting of isolated
spanNear queries at the leaves should have memory issues (as opposed
to nested spanNear queries around disjunctions, which might well do).
Am I misreading the string representation of that query? A little bit
more explicit information about how the query is built, so that we can
be certain of what we're dealing with, would be helpful.
It'd certainly be worth trying IntervalsQuery -- but part of what
makes me think I must be missing something in interpreting the string
representation of the query provided: it seems that simple phrase
queries would suffice here in place of spanNear?
Regarding SpanQuery vs. IntervalsQuery performance and
characteristics, there's some possibly-relevant discussion on
LUCENE-9204:
https://issues.apache.org/jira/browse/LUCENE-9204?focusedCommentId=17352589#comment-17352589
Michael
On Wed, Dec 14, 2022 at 1:27 PM Mikhail Khludnev <m...@apache.org>
wrote:
>
> Developers,
> Is it expected for Spans? Can IntervalsQuery help here?
>
> On Wed, Dec 14, 2022 at 5:41 PM Sjoerd Smeets
<ssme...@gmail.com> wrote:
>>
>> Hi,
>>
>> I've implemented a Span Query parser and when running the below
query, I'm
>> seeing Heap Size Space messages on certain shards:
>>
>> o.a.s.s.HttpSolrCall null:java.lang.RuntimeException:
>> java.lang.OutOfMemoryError: Java heap space
>>
>> The span query that I'm running is the following:
>>
>> ((spanNear([unstemmed_text:charge, unstemmed_text:account], 4,
false)
>> spanNear([unstemmed_text:pledge, unstemmed_text:account], 4,
false))
>> spanNear([unstemmed_text:pledge, unstemmed_text:deposit], 4,
false))
>> spanNear([unstemmed_text:charge, unstemmed_text:deposit], 4, false)
>>
>> The heap size at the moment is set to 48Gb. We are running 4
shards in 1
>> JVM and the 4 shards combined have 24M docs evenly distributed
across the
>> shards. We do use the collapse feature as well.
>>
>> This is on Solr 8.6.0
>>
>> What are the considerations for running Span Queries and heap
sizes?
>>
>> Any suggestions are welcome
>>
>> Sjoerd
>
>
>
> --
> Sincerely yours
> Mikhail Khludnev
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