[ES|QL] Implicit numeric casting for CASE/GREATEST/LEAST

docs/changelog/122601.yaml

@@ -0,0 +1,6 @@
+pr: 122601
+summary: Implicit numeric casting for CASE/GREATEST/LEAST
+area: ES|QL
+type: bug
+issues:
+ - 121890

x-pack/plugin/esql/qa/testFixtures/src/main/resources/conditional.csv-spec

@@ -281,3 +281,111 @@ languages:integer| emp_no:integer|eval:keyword
 null             |10020          |languages is null
 null             |10021          |languages is null
 ;
+
+caseWithMixedNumericValue
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| WHERE emp_no >= 10005 AND emp_no <= 10010
+| EVAL g = case(gender == "F", 1.0, gender == "M", 2, 3.0)
+| KEEP emp_no, gender, g
+| SORT emp_no
+;
+
+emp_no:integer | gender:keyword | g:double
+10005          | M              | 2.0
+10006          | F              | 1.0
+10007          | F              | 1.0
+10008          | M              | 2.0
+10009          | F              | 1.0
+10010          | null           | 3.0
+;
+
+caseWithMixedNumericValueWithNull
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| WHERE emp_no >= 10005 AND emp_no <= 10010
+| EVAL g = case(gender == "F", 1.0, gender == "M", 2, null)
+| KEEP emp_no, gender, g
+| SORT emp_no
+;
+
+emp_no:integer | gender:keyword | g:double
+10005          | M              | 2.0
+10006          | F              | 1.0
+10007          | F              | 1.0
+10008          | M              | 2.0
+10009          | F              | 1.0
+10010          | null           | null
+;
+
+caseWithMixedNumericField
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| WHERE emp_no >= 10005 AND emp_no <= 10010
+| EVAL g = case(gender == "F", height, gender == "M", salary, languages)
+| KEEP emp_no, gender, g
+| SORT emp_no
+;
+
+emp_no:integer | gender:keyword | g:double
+10005          | M              | 63528.0
+10006          | F              | 1.56
+10007          | F              | 1.7
+10008          | M              | 43906.0
+10009          | F              | 1.85
+10010          | null           | 4.0
+;
+
+caseWithMixedNumericFieldWithNull
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| WHERE emp_no >= 10005 AND emp_no <= 10010
+| EVAL g = case(gender == "F", height, gender == "M", salary, null)
+| KEEP emp_no, gender, g
+| SORT emp_no
+;
+
+emp_no:integer | gender:keyword | g:double
+10005          | M              | 63528.0
+10006          | F              | 1.56
+10007          | F              | 1.7
+10008          | M              | 43906.0
+10009          | F              | 1.85
+10010          | null           | null
+;
+
+caseWithMixedNumericFieldWithMV
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| WHERE emp_no >= 10005 AND emp_no <= 10010
+| EVAL g = case(gender == "F", salary_change, gender == "M", salary, languages)
+| KEEP emp_no, gender, g
+| SORT emp_no
+;
+
+emp_no:integer | gender:keyword | g:double
+10005          | M              | 63528.0
+10006          | F              | -3.9
+10007          | F              | [-7.06, 0.57, 1.99]
+10008          | M              | 43906.0
+10009          | F              | null
+10010          | null           | 4.0
+;
+
+caseWithMixedNumericFieldWithNullWithMV
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| WHERE emp_no >= 10005 AND emp_no <= 10010
+| EVAL g = case(gender == "F", salary_change, gender == "M", salary, null)
+| KEEP emp_no, gender, g
+| SORT emp_no
+;
+
+emp_no:integer | gender:keyword | g:double
+10005          | M              | 63528.0
+10006          | F              | -3.9
+10007          | F              | [-7.06, 0.57, 1.99]
+10008          | M              | 43906.0
+10009          | F              | null
+10010          | null           | null
+;

x-pack/plugin/esql/qa/testFixtures/src/main/resources/math.csv-spec

@@ -1583,3 +1583,95 @@ emp_no: integer | x:date     | y:date
 10001           | 2024-11-03 | 2024-11-06
 10002           | 2024-11-03 | 2024-11-06
 ;
+
+greatestWithMixedNumericValues
+required_capability: mixed_numeric_types_in_case_greatest_least
+ROW g1=GREATEST(10.0, 5.0, 1, -100.1, 0, 1234, -10000), g2=GREATEST(10.0, 5, 1, -100.1, null);
+
+g1:double |g2:double
+1234      |null
+;
+
+leastWithMixedNumericValues
+required_capability: mixed_numeric_types_in_case_greatest_least
+ROW l1=LEAST(10.0, 5.0, 1, -100.1, 0, 1234, -10000), l2=LEAST(10.0, 5, 1, -100.1, null);
+
+l1:double |l2:double
+-10000    |null
+;
+
+greatestWithMixedNumericFields
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| EVAL g1 = GREATEST(height, salary, languages), g2 = GREATEST(height, salary, languages, null)
+| KEEP emp_no, g1, g2
+| SORT emp_no
+| LIMIT 3
+;
+
+emp_no:integer | g1:double | g2:double
+10001          | 57305.0   | null
+10002          | 56371.0   | null
+10003          | 61805.0   | null
+;
+
+leastWithMixedNumericFields
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| EVAL l1 = LEAST(height, salary, languages), l2 = LEAST(height, salary, languages, null)
+| KEEP emp_no, l1, l2
+| SORT emp_no
+| LIMIT 3
+;
+
+emp_no:integer | l1:double | l2:double
+10001          | 2.0       | null
+10002          | 2.08      | null
+10003          | 1.83      | null
+;
+
+greatestWithMixedNumericValuesWithMV
+required_capability: mixed_numeric_types_in_case_greatest_least
+ROW g1=GREATEST([10.0, 4], 1), g2=GREATEST([10.0, 4], 1, null);
+
+g1:double |g2:double
+10        |null
+;
+
+leastWithMixedNumericValuesWithMV
+required_capability: mixed_numeric_types_in_case_greatest_least
+ROW l1=LEAST([10.0, 4], 1), l2=LEAST([10.0, 4], 1, null);
+
+l1:double |l2:double
+1         |null
+;
+
+greatestWithMixedNumericFieldsWithMV
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| EVAL g1 = GREATEST(salary_change, salary, languages), g2 = GREATEST(salary_change, salary, languages, null)
+| KEEP emp_no, g1, g2
+| SORT emp_no
+| LIMIT 3
+;
+
+emp_no:integer | g1:double | g2:double
+10001          | 57305.0   | null
+10002          | 56371.0   | null
+10003          | 61805.0   | null
+;
+
+leastWithMixedNumericFieldsWithMV
+required_capability: mixed_numeric_types_in_case_greatest_least
+FROM employees
+| EVAL l1 = LEAST(salary_change, salary, languages), l2 = LEAST(salary_change, salary, languages, null)
+| KEEP emp_no, l1, l2
+| SORT emp_no
+| LIMIT 3
+;
+
+emp_no:integer | l1:double | l2:double
+10001          | 1.19      | null     
+10002          | -7.23     | null     
+10003          | 4.0       | null     
+;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -824,7 +824,12 @@ public enum Cap {
         /**
          * Support partial_results
          */
-        SUPPORT_PARTIAL_RESULTS;
+        SUPPORT_PARTIAL_RESULTS,
+
+        /**
+         * Allow mixed numeric types in conditional functions - case, greatest and least
+         */
+        MIXED_NUMERIC_TYPES_IN_CASE_GREATEST_LEAST;
 
         private final boolean enabled;
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/analysis/Analyzer.java

@@ -52,6 +52,9 @@
 import org.elasticsearch.xpack.esql.expression.function.UnsupportedAttribute;
 import org.elasticsearch.xpack.esql.expression.function.grouping.GroupingFunction;
 import org.elasticsearch.xpack.esql.expression.function.scalar.EsqlScalarFunction;
+import org.elasticsearch.xpack.esql.expression.function.scalar.conditional.Case;
+import org.elasticsearch.xpack.esql.expression.function.scalar.conditional.Greatest;
+import org.elasticsearch.xpack.esql.expression.function.scalar.conditional.Least;
 import org.elasticsearch.xpack.esql.expression.function.scalar.convert.AbstractConvertFunction;
 import org.elasticsearch.xpack.esql.expression.function.scalar.convert.FoldablesConvertFunction;
 import org.elasticsearch.xpack.esql.expression.function.scalar.convert.ToDouble;
@@ -1257,7 +1260,7 @@ private static Expression processIn(In in) {
         }
 
         private static boolean canCastMixedNumericTypes(org.elasticsearch.xpack.esql.core.expression.function.Function f) {
-            return f instanceof Coalesce;
+            return f instanceof Coalesce || f instanceof Case || f instanceof Greatest || f instanceof Least;
         }
 
         private static boolean canCastNumeric(DataType from, DataType to) {

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/analysis/AnalyzerTests.java

@@ -2325,13 +2325,37 @@ public void testRateRequiresCounterTypes() {
         );
     }
 
-    public void testCoalesceWithMixedNumericTypes() {
+    public void testConditionalFunctionsWithMixedNumericTypes() {
         LogicalPlan plan = analyze("""
             from test
             | eval x = coalesce(salary_change, null, 0), y = coalesce(languages, null, 0), z = coalesce(languages.long, null, 0)
             , w = coalesce(salary_change, null, 0::long)
             | keep x, y, z, w
             """, "mapping-default.json");
+        validateConditionalFunctions(plan);
+
+        plan = analyze("""
+            from test
+            | eval x = case(languages == 1, salary_change, languages == 2, salary, languages == 3, salary_change.long, 0)
+                   , y = case(languages == 1, salary_change.int, languages == 2, salary, 0)
+                   , z = case(languages == 1, salary_change.long, languages == 2, salary, 0::long)
+                   , w = case(languages == 1, salary_change, languages == 2, salary, languages == 3, salary_change.long, null)
+            | keep x, y, z, w
+            """, "mapping-default.json");
+        validateConditionalFunctions(plan);
+
+        plan = analyze("""
+            from test
+            | eval x = greatest(salary_change, salary, salary_change.long)
+                   , y = least(salary_change.int, salary)
+                   , z = greatest(salary_change.long, salary, null)
+                   , w = least(null, salary_change, salary_change.long, salary, null)
+            | keep x, y, z, w
+            """, "mapping-default.json");
+        validateConditionalFunctions(plan);
+    }
+
+    private void validateConditionalFunctions(LogicalPlan plan) {
         var limit = as(plan, Limit.class);
         var esqlProject = as(limit.child(), EsqlProject.class);
         List<?> projections = esqlProject.projections();