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_r334009994
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File path: lucene/core/src/java/org/apache/lucene/search/LRUQueryCache.java
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@@ -732,8 +741,39 @@ public ScorerSupplier scorerSupplier(LeafReaderContext
context) throws IOExcepti
if (docIdSet == null) {
if (policy.shouldCache(in.getQuery())) {
- docIdSet = cache(context);
- putIfAbsent(in.getQuery(), docIdSet, cacheHelper);
+ final ScorerSupplier supplier = in.scorerSupplier(context);
+ if (supplier == null) {
+ putIfAbsent(in.getQuery(), DocIdSet.EMPTY, cacheHelper);
+ return null;
+ }
+
+ final long cost = supplier.cost();
+ return new ScorerSupplier() {
+ @Override
+ public Scorer get(long leadCost) throws IOException {
+ // skip cache operation which would slow query down too much
+ if ((cost > skipCacheCost || cost > leadCost * skipCacheFactor)
Review comment:
> control the time used for caching as the caching time is related to the
cost of range query
Understood, but if the query has a 250x higher cost already, then it's
probably fine right?
> skip caching too large range queries which will consume too much memory
and evict cache entries frequently
Maybe a more intuitive way to do that would be to call this parameter
`maxRamBytesUsedPerEntry` and skip caching if `min(maxDoc/Byte.SIZE /* assuming
bitset */, cost * Short.BYTES /* assuming short[] */) >
maxRamBytesUsedPerEntry`?
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