UPDATE – July 9, 2024

Heads up, Solr wranglers! We’ve moved the maxBooleanClauses setting into your solr.xml (in your Solr home directory alongside your cores/collections).

<solr>
  <int name="maxBooleanClauses">90589</int>  <!-- 🛠️ Bump your limit here -->
  <shardHandlerFactory name="shardHandlerFactory"
                       class="HttpShardHandlerFactory">
    <int name="socketTimeout">${socketTimeout:600000}</int>
    <int name="connTimeout">${connTimeout:60000}</int>
  </shardHandlerFactory>
</solr>

😱 Symptom

org.apache.solr.common.SolrException: Too many boolean clauses (1025).

• Default limit: 1024 clauses.
• Triggers: large synonym files, wildcard expansions, or overly broad query filters.

🔍 Root Causes

• Synonym explosion: Each synonym generates extra clauses.
• Wildcard & prefix queries: * or leading wildcards (*term) expand to many terms.
• Massive stopword/protword lists: Improperly positioned filters multiply clauses.

🛠️ Solutions

1. Increase maxBooleanClauses
   Adjust in solr.xml (as shown above).

2. Trim your word lists

   • synonyms.txt
   • stopwords.txt
   • protwords.txt
     Remove rarely used terms to reduce clause count.

3. Optimize filter chain

   • Apply synonyms at query time using SynonymGraphFilterFactory, not at index time.
   • Place stop and prot word filters before wildcard or graph filters.

4. Avoid expansive wildcards

   • Prefer prefix queries (term*) over leading wildcards.
   • Use edge n-gram tokenizers for partial matching.

Keep calm and Solr on! 😎🖋️