Add scorable() method to Query class, and take it into account for creating boolean queries

Author: carlosdelest

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/querydsl/query/BoolQuery.java

@@ -46,10 +46,15 @@ public BoolQuery(Source source, boolean isAnd, List<Query> queries) {
     public QueryBuilder asBuilder() {
         BoolQueryBuilder boolQuery = boolQuery();
         for (Query query : queries) {
+            QueryBuilder queryBuilder = query.asBuilder();
             if (isAnd) {
-                boolQuery.must(query.asBuilder());
+                if (query.scorable()) {
+                    boolQuery.must(queryBuilder);
+                } else {
+                    boolQuery.filter(queryBuilder);
+                }
             } else {
-                boolQuery.should(query.asBuilder());
+                boolQuery.should(queryBuilder);
             }
         }
         return boolQuery;

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/querydsl/query/Query.java

@@ -85,4 +85,13 @@ public String toString() {
     public Query negate(Source source) {
         return new NotQuery(source, this);
     }
+
+    /**
+     * Defines whether a query should be scored or not
+     *
+     * @return true if the query should be scored
+     */
+    public boolean scorable() {
+        return false;
+    }
 }

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/util/Queries.java

@@ -51,6 +51,9 @@ public static QueryBuilder combine(Clause clause, List<QueryBuilder> queries) {
                 firstQuery = query;
                 if (firstQuery instanceof BoolQueryBuilder bqb) {
                     bool = bqb.shallowCopy();
+                } else if (clause == Clause.FILTER) {
+                    // Filter is wrapped in a bool query to ensure scoring is not calculated
+                    bool = combine(clause, boolQuery(), query);
                 }
             }
             // at least two entries, start copying

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/optimizer/rules/physical/local/PushFiltersToSource.java

@@ -101,7 +101,9 @@ private static PhysicalPlan rewrite(
         if (newPushable.size() > 0) { // update the executable with pushable conditions
             Query queryDSL = TRANSLATOR_HANDLER.asQuery(Predicates.combineAnd(newPushable));
             QueryBuilder planQuery = queryDSL.asBuilder();
-            Queries.Clause combiningQueryClauseType = queryExec.hasScoring() ? Queries.Clause.MUST : Queries.Clause.FILTER;
+            Queries.Clause combiningQueryClauseType = queryExec.hasScoring() && queryDSL.scorable()
+                ? Queries.Clause.MUST
+                : Queries.Clause.FILTER;
             var query = Queries.combine(combiningQueryClauseType, asList(queryExec.query(), planQuery));
             queryExec = new EsQueryExec(
                 queryExec.source(),

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/querydsl/query/TranslationAwareExpressionQuery.java

@@ -34,4 +34,10 @@ public QueryBuilder asBuilder() {
     protected String innerToString() {
         return queryBuilder.toString();
     }
+
+    @Override
+    public boolean scorable() {
+        // All Full Text Functions are translated to queries using this method
+        return true;
+    }
 }