Suggester breaks on large corpus for Solr 7.4

[cdmo]

We recently began experimenting with BL7, Solr 7.4, Rails 5.2 and a 7 million item catalog. In the early testing so far we've noticed that the suggester feature errors out. The Solr web UI log screen will look like this:

ERROR true
x:blacklight-core
SuggestComponent
Exception in building suggester index for: mySuggester

Looking into the logs, the full trace looks like this:

2018-09-13 19:40:12.318 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.h.c.SpellCheckComponent Index is not optimized therefore skipping building spell check index for: default
2018-09-13 19:40:12.318 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.h.c.SpellCheckComponent Index is not optimized therefore skipping building spell check index for: author
2018-09-13 19:40:12.318 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.h.c.SpellCheckComponent Index is not optimized therefore skipping building spell check index for: subject
2018-09-13 19:40:12.318 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.h.c.SpellCheckComponent Index is not optimized therefore skipping building spell check index for: title
2018-09-13 19:40:12.318 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.h.c.SuggestComponent buildOnCommit: mySuggester
2018-09-13 19:40:12.318 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.s.s.SolrSuggester SolrSuggester.build(mySuggester)
2018-09-13 19:40:12.818 ERROR (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.h.c.SuggestComponent Exception in building suggester index for: mySuggester
java.lang.IllegalArgumentException: input automaton is too large: 1001
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1298) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]

( this goes one for 1000 lines)

        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStatesRecurse(Operations.java:1306) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.util.automaton.Operations.topoSortStates(Operations.java:1275) ~[lucene-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:51:45]
        at org.apache.lucene.search.suggest.analyzing.AnalyzingSuggester.replaceSep(AnalyzingSuggester.java:292) ~[lucene-suggest-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:52:17]
        at org.apache.lucene.search.suggest.analyzing.AnalyzingSuggester.toAutomaton(AnalyzingSuggester.java:854) ~[lucene-suggest-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:52:17]
        at org.apache.lucene.search.suggest.analyzing.AnalyzingSuggester.build(AnalyzingSuggester.java:430) ~[lucene-suggest-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:52:17]
        at org.apache.lucene.search.suggest.Lookup.build(Lookup.java:190) ~[lucene-suggest-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:52:17]
        at org.apache.solr.spelling.suggest.SolrSuggester.build(SolrSuggester.java:181) ~[solr-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:55:13]
        at org.apache.solr.handler.component.SuggestComponent$SuggesterListener.buildSuggesterIndex(SuggestComponent.java:534) ~[solr-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:55:13]
        at org.apache.solr.handler.component.SuggestComponent$SuggesterListener.newSearcher(SuggestComponent.java:521) ~[solr-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:55:13]
        at org.apache.solr.core.SolrCore.lambda$getSearcher$18(SolrCore.java:2322) ~[solr-core-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:55:13]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_181]
        at org.apache.solr.common.util.ExecutorUtil$MDCAwareThreadPoolExecutor.lambda$execute$0(ExecutorUtil.java:209) ~[solr-solrj-7.4.0.jar:7.4.0 9060ac689c270b02143f375de0348b7f626adebc - jpountz - 2018-06-18 16:55:14]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_181]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_181]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_181]
2018-09-13 19:40:12.824 INFO  (searcherExecutor-10-thread-1-processing-x:blacklight-core) [   x:blacklight-core] o.a.s.c.SolrCore [blacklight-core] Registered new searcher Searcher@b5ea2d0[blacklight-core] main{ExitableDirectoryReader(UninvertingDirectoryReader(Uninverting(_gy(7.4.0):C2138244/151:delGen=3) Uninverting(_k0(7.4.0):C2025787/58:delGen=2) Uninverting(_if(7.4.0):c125682/2:delGen=1) Uninverting(_mk(7.4.0):C2086012/4:delGen=2) Uninverting(_k8(7.4.0):C10433/38:delGen=2) Uninverting(_l1(7.4.0):C8823/2:delGen=2) Uninverting(_lj(7.4.0):C16528/1:delGen=1) Uninverting(_lk(7.4.0):C17041/1:delGen=1) Uninverting(_lx(7.4.0):C16192) Uninverting(_m0(7.4.0):C17514) Uninverting(_mw(7.4.0):c248023) Uninverting(_mc(7.4.0):C18352/1:delGen=1) Uninverting(_n7(7.4.0):c255323) Uninverting(_mx(7.4.0):C16296/3:delGen=1) Uninverting(_mu(7.4.0):C17043/2:delGen=1) Uninverting(_n0(7.4.0):C20258/2:delGen=1) Uninverting(_n5(7.4.0):C16103/1:delGen=1) Uninverting(_n6(7.4.0):C13497) Uninverting(_n3(7.4.0):C13603) Uninverting(_n8(7.4.0):C4865) Uninverting(_o8(7.4.0):c575/50:delGen=14) Uninverting(_nv(7.4.0):C9761/51:delGen=21) Uninverting(_nw(7.4.0):C5308/51:delGen=18) Uninverting(_p2(7.4.0):c1175/2:delGen=2) Uninverting(_p0(7.4.0):C1364/4:delGen=1) Uninverting(_p3(7.4.0):C97/2:delGen=1) Uninverting(_p4(7.4.0):C51/1:delGen=1) Uninverting(_p5(7.4.0):C98)))}
2018-09-13 19:40:12.825 INFO  (qtp817348612-15) [   x:blacklight-core] o.a.s.u.p.LogUpdateProcessorFactory [blacklight-core]  webapp=/solr path=/update/json params={commit=true}{commit=} 0 572

So, it appears that there is a recursive function that is only permitted to run 1,000 times before it quits. This is, apparently, a change that occurred in Lucene 7.0. Here's an email thread that discusses it:

http://lucene.472066.n3.nabble.com/solr-5-2-gt-7-2-suggester-failure-td4383551.html

Here's the relevant commit (as pointed out in the email thread):

https://github.com/apache/lucene-solr/commit/7dde798473d1a8640edafb41f28ad25d17f25a2d

I'll mention too that the suggester worked fine for us with a small corpus. It appears that once the corpus becomes too large, the suggester struggles. Also, all of our settings in schema.xml and solrconfig.xml are default.

[mejackreed]

Is there a threshold number of documents that you are seeing this happen at?

[cdmo]

Not really. I've only tried a very small number (112) where it works fine, and then 7 million where it stops and reports an error. I could try a smaller sample for troubleshooting.

[mejackreed]

We have experienced the same issue. And I can't recreate it locally even with the same number of documents (locally) as in our production index.

[cdmo]

🤔 I could also try a large number locally and see if the suggester works. Are you using traject in local and prod?

[mejackreed]

This is for our application EarthWorks (GeoBlacklight). Locally we are using GeoCombine for indexing.

[cdmo]

Not a lot of progress here. But, I'll report back, locally with 2.2M records I'm seeing the same error. Same with 98K and 2K and even just 900.

Here's schema.xml fwiw

   <!-- for suggestions -->
   <copyField source="*_t" dest="suggest"/>
   <copyField source="*_facet" dest="suggest"/>

   <dynamicField name="*suggest" type="textSuggest" indexed="true" stored="false" multiValued="true" />

    <fieldType class="solr.TextField" name="textSuggest" positionIncrementGap="100">
       <analyzer>
          <tokenizer class="solr.KeywordTokenizerFactory"/>
          <filter class="solr.StandardFilterFactory"/>
          <filter class="solr.LowerCaseFilterFactory"/>
          <filter class="solr.RemoveDuplicatesTokenFilterFactory"/>
       </analyzer>
    </fieldType>

I wish I could discover where the looping error was occurring, like what part of the process. I did attempt to make the suggest field jus the title_display, and that also errored out.

[barmintor]

Can you get the suggestions to work in Solr via, say, the admin panel? Trying to sort out whether this is a BL issue or a Solr issue.

[mejackreed]

This is a Solr issue AFAICT

[banukutlu]

Can you get the suggestions to work in Solr via, say, the admin panel? Trying to sort out whether this is a BL issue or a Solr issue.

Currently we disabled suggestions but it was not working via the admin panel as well so yes more of a Solr issue.

[mejackreed]

Yep I think how it relates here to Blacklight is this:

Blacklight should ship a default solr config that works at scale with suggester things

[cdmo]

Yep, I mentioned a link to the change in Lucene 7.0 in the original description. So, definitely an upstream problem... upstream change to be fixed downstream at some point I suppose? edit: Also, I have not tested with solr 7.5, just 7.4

[magibney]

This looks to me like a large field value problem, not a large index problem. If you're doing "suggest" over fields with potentially large values (like title "tokenized" as a single string -- note that KeywordTokenizer is specified in the analyzer config above), there would likely be a correlation between index size and maximum indexed field value (particularly for a field like title, with a long tail of a handful of potentially very long values) ... "if you cast a wider net, you're more likely to catch an unusual fish". Have you tested this issue with a small index that's likely to generate large *suggest field values? If it wouldn't adversely affect the usefulness of the suggestions, you could stick a LengthFilter on the end of the analysis chain and see if that helps.

[thePanz]

I can confirm @magibney answer. If the field is analyzed with string and it contains more than 200 words the above exception is thrown. If a "short" field is used with a proper analyzer, the suggester works perfectly. Refer to https://lucidworks.com/2015/03/04/solr-suggester/ for a better explanation and examples.

The confusion, on my side, was related to the examples on the Solr documentation, where the following points are not clear:

• the "whole" field is returned, not just the matching term
• the cat field (used in the techproducts example) is very very short field (~20chars), and NOT a free text field