Fix cases with mix of constant_keyword and other types

Author: luigidellaquila

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/stats/SearchContextStats.java

@@ -338,6 +338,8 @@ public String constantValue(String name) {
                 } else if (thisVal.equals(val) == false) {
                     return null;
                 }
+            } else {
+                return null;
             }
         }
         return val;

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/esql/30_types.yml

@@ -49,6 +49,27 @@ constant_keyword:
           - { "index": { } }
           - { "color": "blue" }
 
+  - do:
+      indices.create:
+        index:  test_3
+        body:
+          mappings:
+            properties:
+              kind:
+                type: keyword
+              color:
+                type: keyword
+
+  - do:
+      bulk:
+        index: test_3
+        refresh: true
+        body:
+          - { "index": { } }
+          - { "kind":"not a constant", "color": "pink" }
+          - { "index": { } }
+          - { "kind": "still no constant", "color": "pink" }
+
   - do:
       allowed_warnings_regex:
         - "No limit defined, adding default limit of \\[.*\\]"
@@ -121,6 +142,21 @@ constant_keyword:
   - length: {values: 1}
   - match: {values.0.0: wow such constant}
 
+  - do:
+      allowed_warnings_regex:
+        - "No limit defined, adding default limit of \\[.*\\]"
+      esql.query:
+        body:
+          query: 'from test,test_2 | where kind == "wow such constant" | keep color, kind'
+  - match: {columns.0.name: color}
+  - match: {columns.0.type: keyword}
+  - match: { columns.1.name: kind }
+  - match: { columns.1.type: keyword }
+  - length: {values: 1}
+  - match: {values.0.0: red}
+  - match: {values.0.1: "wow such constant"}
+
+
   - do:
       allowed_warnings_regex:
         - "No limit defined, adding default limit of \\[.*\\]"
@@ -135,20 +171,84 @@ constant_keyword:
   - match: {values.0.0: red}
   - match: {values.0.1: "wow such constant"}
 
+  - do:
+      allowed_warnings_regex:
+        - "No limit defined, adding default limit of \\[.*\\]"
+      esql.query:
+        body:
+          query: 'from test,test_2 | where kind == "wow such constant" | keep color, kind'
+  - match: {columns.0.name: color}
+  - match: {columns.0.type: keyword}
+  - match: { columns.1.name: kind }
+  - match: { columns.1.type: keyword }
+  - length: {values: 1}
+  - match: {values.0.0: red}
+  - match: {values.0.1: "wow such constant"}
+
 
   - do:
       allowed_warnings_regex:
         - "No limit defined, adding default limit of \\[.*\\]"
       esql.query:
         body:
-          query: 'from test* | where kind >=  "a" | keep color, kind | sort color'
+          query: 'from test* | where kind == "wow such constant" | keep color, kind'
   - match: {columns.0.name: color}
   - match: {columns.0.type: keyword}
   - match: { columns.1.name: kind }
   - match: { columns.1.type: keyword }
-  - length: {values: 2}
+  - length: {values: 1}
+  - match: {values.0.0: red}
+  - match: {values.0.1: "wow such constant"}
+
+
+  - do:
+      allowed_warnings_regex:
+        - "No limit defined, adding default limit of \\[.*\\]"
+      esql.query:
+        body:
+          query: 'from test* | where kind == "not a constant" | keep color, kind'
+  - match: {columns.0.name: color}
+  - match: {columns.0.type: keyword}
+  - match: { columns.1.name: kind }
+  - match: { columns.1.type: keyword }
+  - length: {values: 1}
+  - match: {values.0.0: pink}
+  - match: {values.0.1: "not a constant"}
+
+  - do:
+      allowed_warnings_regex:
+        - "No limit defined, adding default limit of \\[.*\\]"
+      esql.query:
+        body:
+          query: 'from test* | where kind >=  "a" | keep color, kind | sort color, kind'
+  - match: {columns.0.name: color}
+  - match: {columns.0.type: keyword}
+  - match: { columns.1.name: kind }
+  - match: { columns.1.type: keyword }
+  - length: {values: 4}
   - match: {values.0.0: blue}
   - match: {values.0.1: "a different constant"}
+  - match: {values.1.0: pink}
+  - match: {values.1.1: "not a constant"}
+  - match: {values.2.0: pink}
+  - match: {values.2.1: "still no constant"}
+  - match: {values.3.0: red}
+  - match: {values.3.1: "wow such constant"}
+
+
+  - do:
+      allowed_warnings_regex:
+        - "No limit defined, adding default limit of \\[.*\\]"
+      esql.query:
+        body:
+          query: 'from test* | where kind >=  "o" | keep color, kind | sort color, kind'
+  - match: {columns.0.name: color}
+  - match: {columns.0.type: keyword}
+  - match: { columns.1.name: kind }
+  - match: { columns.1.type: keyword }
+  - length: {values: 2}
+  - match: {values.0.0: pink}
+  - match: {values.0.1: "still no constant"}
   - match: {values.1.0: red}
   - match: {values.1.1: "wow such constant"}