Add use-estimate-for-fetch-postings feature flag

4 files changed, 16 insertions, 0 deletions

diff --git a/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java b/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
index cb394054510..f34f63a0cfc 100644
--- a/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
+++ b/config-model-api/src/main/java/com/yahoo/config/model/api/ModelContext.java
@@ -117,6 +117,7 @@ public interface ModelContext {
         @ModelFeatureFlag(owners = {"vekterli"}) default boolean usePerDocumentThrottledDeleteBucket() { return false; }
         @ModelFeatureFlag(owners = {"baldersheim"}) default boolean alwaysMarkPhraseExpensive() { return false; }
         @ModelFeatureFlag(owners = {"baldersheim"}) default boolean createPostinglistWhenNonStrict() { return true; }
+        @ModelFeatureFlag(owners = {"baldersheim"}) default boolean useEstimateForFetchPostings() { return false; }
     }
 
     /** Warning: As elsewhere in this package, do not make backwards incompatible changes that will break old config models! */
diff --git a/config-model/src/main/java/com/yahoo/schema/derived/RawRankProfile.java b/config-model/src/main/java/com/yahoo/schema/derived/RawRankProfile.java
index 411e754f3ef..8090344ea8c 100644
--- a/config-model/src/main/java/com/yahoo/schema/derived/RawRankProfile.java
+++ b/config-model/src/main/java/com/yahoo/schema/derived/RawRankProfile.java
@@ -172,6 +172,7 @@ public class RawRankProfile implements RankProfilesConfig.Producer {
         private final double rankScoreDropLimit;
         private final boolean alwaysMarkPhraseExpensive;
         private final boolean createPostinglistWhenNonStrict;
+        private final boolean useEstimateForFetchPostings;
 
         /**
          * The rank type definitions used to derive settings for the native rank features
@@ -215,6 +216,7 @@ public class RawRankProfile implements RankProfilesConfig.Producer {
             termwiseLimit = compiled.getTermwiseLimit().orElse(deployProperties.featureFlags().defaultTermwiseLimit());
             alwaysMarkPhraseExpensive = deployProperties.featureFlags().alwaysMarkPhraseExpensive();
             createPostinglistWhenNonStrict = deployProperties.featureFlags().createPostinglistWhenNonStrict();
+            useEstimateForFetchPostings = deployProperties.featureFlags().useEstimateForFetchPostings();
             postFilterThreshold = compiled.getPostFilterThreshold();
             approximateThreshold = compiled.getApproximateThreshold();
             targetHitsMaxAdjustmentFactor = compiled.getTargetHitsMaxAdjustmentFactor();
@@ -471,6 +473,9 @@ public class RawRankProfile implements RankProfilesConfig.Producer {
             if ( ! createPostinglistWhenNonStrict) {
                 properties.add(new Pair<>("vespa.matching.create_postinglist_when_non_strict", String.valueOf(createPostinglistWhenNonStrict)));
             }
+            if (useEstimateForFetchPostings) {
+                properties.add(new Pair<>("vespa.matching.use_estimate_for_fetch_postings", String.valueOf(useEstimateForFetchPostings)));
+            }
             if (postFilterThreshold.isPresent()) {
                 properties.add(new Pair<>("vespa.matching.global_filter.upper_limit", String.valueOf(postFilterThreshold.getAsDouble())));
             }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java
index 27c24c5d6ed..2f126cd84d3 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ModelContextImpl.java
@@ -203,6 +203,7 @@ public class ModelContextImpl implements ModelContext {
         private final String summaryDecodePolicy;
         private final boolean alwaysMarkPhraseExpensive;
         private final boolean createPostinglistWhenNonStrict;
+        private final boolean useEstimateForFetchPostings;
         private final int contentLayerMetadataFeatureLevel;
         private final boolean dynamicHeapSize;
         private final String unknownConfigDefinition;
@@ -254,6 +255,7 @@ public class ModelContextImpl implements ModelContext {
             this.usePerDocumentThrottledDeleteBucket = flagValue(source, appId, version, Flags.USE_PER_DOCUMENT_THROTTLED_DELETE_BUCKET);
             this.alwaysMarkPhraseExpensive =  flagValue(source, appId, version, Flags.ALWAYS_MARK_PHRASE_EXPENSIVE);
             this.createPostinglistWhenNonStrict = flagValue(source, appId, version, Flags.CREATE_POSTINGLIST_WHEN_NON_STRICT);
+            this.useEstimateForFetchPostings = flagValue(source, appId, version, Flags.USE_ESTIMATE_FOR_FETCH_POSTINGS);
         }
 
         @Override public int heapSizePercentage() { return heapPercentage; }
@@ -301,6 +303,7 @@ public class ModelContextImpl implements ModelContext {
         }
         @Override public boolean alwaysMarkPhraseExpensive() { return alwaysMarkPhraseExpensive; }
         @Override public boolean createPostinglistWhenNonStrict() { return createPostinglistWhenNonStrict; }
+        @Override public boolean useEstimateForFetchPostings() { return useEstimateForFetchPostings; }
         @Override public int contentLayerMetadataFeatureLevel() { return contentLayerMetadataFeatureLevel; }
         @Override public boolean dynamicHeapSize() { return dynamicHeapSize; }
         @Override public String unknownConfigDefinition() { return unknownConfigDefinition; }
diff --git a/flags/src/main/java/com/yahoo/vespa/flags/Flags.java b/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
index 5e395f04956..5af7c82a8c4 100644
--- a/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
+++ b/flags/src/main/java/com/yahoo/vespa/flags/Flags.java
@@ -334,6 +334,13 @@ public class Flags {
             "Takes effect at redeployment",
             INSTANCE_ID);
 
+    public static final UnboundBooleanFlag USE_ESTIMATE_FOR_FETCH_POSTINGS = defineFeatureFlag(
+            "use-estimate-for-fetch-postings", false,
+            List.of("baldersheim"), "2023-12-06", "2024-01-31",
+            "If true an estimate assuming uncorrelated query terms is used in Blueprint::fetchPostings",
+            "Takes effect at redeployment",
+            INSTANCE_ID);
+
     public static final UnboundBooleanFlag WRITE_CONFIG_SERVER_SESSION_DATA_AS_ONE_BLOB = defineFeatureFlag(
             "write-config-server-session-data-as-blob", false,
             List.of("hmusum"), "2023-07-19", "2024-02-01",