Use in-memory database if the limit is lower than 8192

src/main/java/it/cavallium/dbengine/lucene/searcher/AdaptiveMultiSearcher.java

@@ -53,12 +53,14 @@ public class AdaptiveMultiSearcher implements MultiSearcher {
 			LLSearchTransformer transformer) {
 		// offset + limit
 		long realLimit = queryParams.offsetLong() + queryParams.limitLong();
+		long maxAllowedInMemoryLimit
+				= Math.max(MultiSearcher.MAX_IN_MEMORY_SIZE, (long) queryParams.pageLimits().getPageLimit(0));
 
 		return LLUtils.usingSendResource(indexSearchersMono, indexSearchers -> {
 			if (queryParams.limitLong() == 0) {
 				return count.collectMulti(indexSearchersMono, queryParams, keyFieldName, transformer);
 			} else if (queryParams.isSorted() || queryParams.needsScores()) {
-				if (realLimit <= (long) queryParams.pageLimits().getPageLimit(0)) {
+				if (realLimit <= maxAllowedInMemoryLimit) {
 					return scoredPaged.collectMulti(indexSearchersMono, queryParams, keyFieldName, transformer);
 				} else {
 					if ((queryParams.isSorted() && !queryParams.isSortedByScore())) {
@@ -67,7 +69,7 @@ public class AdaptiveMultiSearcher implements MultiSearcher {
 						return unsortedScoredFull.collectMulti(indexSearchersMono, queryParams, keyFieldName, transformer);
 					}
 				}
-			} else if (realLimit <= (long) queryParams.pageLimits().getPageLimit(0)) {
+			} else if (realLimit <= maxAllowedInMemoryLimit) {
 				// Run single-page searches using the paged multi searcher
 				return unsortedUnscoredPaged.collectMulti(indexSearchersMono, queryParams, keyFieldName, transformer);
 			} else {

src/main/java/it/cavallium/dbengine/lucene/searcher/MultiSearcher.java

@@ -7,6 +7,11 @@ import reactor.core.publisher.Mono;
 
 public interface MultiSearcher extends LocalSearcher {
 
+	/**
+	 * Use in-memory collectors if the expected results count is lower or equal than this limit
+	 */
+	int MAX_IN_MEMORY_SIZE = 8192;
+
 	/**
 	 * @param indexSearchersMono Lucene index searcher
 	 * @param queryParams        the query parameters

src/main/java/it/cavallium/dbengine/lucene/searcher/SortedScoredFullMultiSearcher.java

@@ -16,6 +16,7 @@ import java.io.Closeable;
 import java.io.IOException;
 import java.util.ServiceLoader;
 import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.TopFieldCollector;
 import org.warp.commonutils.log.Logger;
 import org.warp.commonutils.log.LoggerFactory;
 import reactor.core.publisher.Flux;
@@ -64,6 +65,9 @@ public class SortedScoredFullMultiSearcher implements MultiSearcher {
 				.fromCallable(() -> {
 					LLUtils.ensureBlocking();
 					var totalHitsThreshold = queryParams.getTotalHitsThresholdLong();
+					if (queryParams.limitLong() < MAX_IN_MEMORY_SIZE) {
+						throw new UnsupportedOperationException("Allowed limit is " + MAX_IN_MEMORY_SIZE + " or greater");
+					}
 					return LMDBFullFieldDocCollector.createSharedManager(env, queryParams.sort(), queryParams.limitInt(),
 							totalHitsThreshold);
 				})

src/main/java/it/cavallium/dbengine/lucene/searcher/UnsortedScoredFullMultiSearcher.java

@@ -69,6 +69,9 @@ public class UnsortedScoredFullMultiSearcher implements MultiSearcher {
 		return Mono
 				.fromCallable(() -> {
 					LLUtils.ensureBlocking();
+					if (queryParams.limitLong() < MAX_IN_MEMORY_SIZE) {
+						throw new UnsupportedOperationException("Allowed limit is " + MAX_IN_MEMORY_SIZE + " or greater");
+					}
 					var totalHitsThreshold = queryParams.getTotalHitsThresholdLong();
 					return LMDBFullScoreDocCollector.createSharedManager(env, queryParams.limitLong(), totalHitsThreshold);
 				})