[GitHub] [lucene-solr] jpountz commented on a change in pull request #940: LUCENE-9002: Query caching leads to absurdly slow queries

[GitBox <gi...@apache.org>]

jpountz commented on a change in pull request #940: LUCENE-9002: Query caching leads to absurdly slow queries
URL: https://github.com/apache/lucene-solr/pull/940#discussion_r343917507
 
 

 ##########
 File path: lucene/core/src/java/org/apache/lucene/search/LRUQueryCache.java
 ##########
 @@ -114,12 +115,20 @@
    * Expert: Create a new instance that will cache at most <code>maxSize</code>
    * queries with at most <code>maxRamBytesUsed</code> bytes of memory, only on
    * leaves that satisfy {@code leavesToCache}.
+   *
+   * Also, clauses whose cost is {@code skipCacheFactor} times more than the cost of the top-level query
+   * will not be cached in order to not slow down queries too much.
    */
   public LRUQueryCache(int maxSize, long maxRamBytesUsed,
-      Predicate<LeafReaderContext> leavesToCache) {
+                       Predicate<LeafReaderContext> leavesToCache, float skipCacheFactor) {
     this.maxSize = maxSize;
     this.maxRamBytesUsed = maxRamBytesUsed;
     this.leavesToCache = leavesToCache;
+    if (skipCacheFactor < 1) {
 
 Review comment:
   ```suggestion
       if (skipCacheFactor >= 1 == false) { // NaN >= 1 evaluates true
   ```

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