From d931ed9924cec39e379eb668cc49fd977f4bc0d4 Mon Sep 17 00:00:00 2001
From: Marios Trivyzas <matriv@gmail.com>
Date: Wed, 24 Oct 2018 15:14:48 +0200
Subject: [PATCH] SQL: Fix edge case: `<field> IN(null)

Handle the case when `null` is the only value in the list so that
it's translated to a `MatchNoDocsQuery`.

Followup to: #34750
---
 .../xpack/sql/querydsl/query/TermsQuery.java     | 11 ++++++++---
 .../xpack/sql/planner/QueryTranslatorTests.java  | 16 +++++++++++++++-
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/querydsl/query/TermsQuery.java b/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/querydsl/query/TermsQuery.java
index 4366e2d404c13a..91ea49a8a3ce3d 100644
--- a/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/querydsl/query/TermsQuery.java
+++ b/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/querydsl/query/TermsQuery.java
@@ -11,23 +11,28 @@
 import org.elasticsearch.xpack.sql.tree.Location;
 import org.elasticsearch.xpack.sql.type.DataType;
 
+import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Objects;
+import java.util.Set;
 
 import static org.elasticsearch.index.query.QueryBuilders.termsQuery;
 
 public class TermsQuery extends LeafQuery {
 
     private final String term;
-    private final LinkedHashSet<Object> values;
+    private final Set<Object> values;
 
     public TermsQuery(Location location, String term, List<Expression> values) {
         super(location);
         this.term = term;
         values.removeIf(e -> e.dataType() == DataType.NULL);
-        this.values = new LinkedHashSet<>(Foldables.valuesOf(values, values.get(0).dataType()));
-        this.values.removeIf(Objects::isNull);
+        if (values.isEmpty()) {
+            this.values = Collections.emptySet();
+        } else {
+            this.values = new LinkedHashSet<>(Foldables.valuesOf(values, values.get(0).dataType()));
+        }
     }
 
     @Override
diff --git a/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/planner/QueryTranslatorTests.java b/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/planner/QueryTranslatorTests.java
index 95b9be33a12a05..54f6ed6480414f 100644
--- a/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/planner/QueryTranslatorTests.java
+++ b/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/planner/QueryTranslatorTests.java
@@ -173,7 +173,7 @@ public void testTranslateInExpression_WhereClause() throws IOException {
         assertEquals("keyword:(bar foo lala)", tq.asBuilder().toQuery(createShardContext()).toString());
     }
 
-    public void testTranslateInExpression_WhereClauseAndNullHAndling() throws IOException {
+    public void testTranslateInExpression_WhereClauseAndNullHandling() throws IOException {
         LogicalPlan p = plan("SELECT * FROM test WHERE keyword IN ('foo', null, 'lala', null, 'foo', concat('la', 'la'))");
         assertTrue(p instanceof Project);
         assertTrue(p.children().get(0) instanceof Filter);
@@ -186,6 +186,20 @@ public void testTranslateInExpression_WhereClauseAndNullHAndling() throws IOExce
         assertEquals("keyword:(foo lala)", tq.asBuilder().toQuery(createShardContext()).toString());
     }
 
+    public void testTranslateInExpression_WhereClauseAndNullHandlingEmptyValuesList() throws IOException {
+        LogicalPlan p = plan("SELECT * FROM test WHERE keyword IN (null)");
+        assertTrue(p instanceof Project);
+        assertTrue(p.children().get(0) instanceof Filter);
+        Expression condition = ((Filter) p.children().get(0)).condition();
+        assertFalse(condition.foldable());
+        QueryTranslation translation = QueryTranslator.toQuery(condition, false);
+        Query query = translation.query;
+        assertTrue(query instanceof TermsQuery);
+        TermsQuery tq = (TermsQuery) query;
+        assertEquals("MatchNoDocsQuery(\"No terms supplied for \"terms\" query.\")",
+            tq.asBuilder().toQuery(createShardContext()).toString());
+    }
+
     public void testTranslateInExpressionInvalidValues_WhereClause() {
         LogicalPlan p = plan("SELECT * FROM test WHERE keyword IN ('foo', 'bar', keyword)");
         assertTrue(p instanceof Project);