jgq2008303393 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_r333896983
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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)
+ && in.getQuery() instanceof IndexOrDocValuesQuery) {
Review comment:
This PR is mainly for IndexOrDocValuesQuery now.
As discussed earlier, the reason why IndexOrDocValuesQuery slow down is that
a large amount of data will be read during caching action, while only a small
amount of data will be read from doc values when not caching. I don't find any
other type of query that reads much more data for caching than it really needs.
@jpountz Looking forward to more discussions if you this PR should apply to
all query types.
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