[ESQL] Support datetime data type in Least and Greatest functions (#113961) (#114138)

not-napoleon · elasticmachine · web-flow · commit 7f05beeff3e0 · 2024-10-05T00:55:03.000+10:00
While working on Date Nanos, I noticed that Least and Greatest didn't have support for datetime. This PR corrects that and adds tests for it.

It seems to me that resolveType() is doing the wrong thing for these functions, as it accepts types that then do not have evaluator mappings, but refactoring that seems out of scope right now.

---------

Co-authored-by: Elastic Machine &lt;elasticmachine@users.noreply.github.com&gt;
diff --git a/docs/changelog/113961.yaml b/docs/changelog/113961.yaml
@@ -0,0 +1,5 @@
+pr: 113961
+summary: "[ESQL] Support datetime data type in Least and Greatest functions"
+area: ES|QL
+type: bug
+issues: []
diff --git a/docs/reference/esql/functions/kibana/definition/greatest.json b/docs/reference/esql/functions/kibana/definition/greatest.json
diff --git a/docs/reference/esql/functions/kibana/definition/least.json b/docs/reference/esql/functions/kibana/definition/least.json
diff --git a/docs/reference/esql/functions/types/greatest.asciidoc b/docs/reference/esql/functions/types/greatest.asciidoc
diff --git a/docs/reference/esql/functions/types/least.asciidoc b/docs/reference/esql/functions/types/least.asciidoc
diff --git a/x-pack/plugin/esql/qa/testFixtures/src/main/resources/date.csv-spec b/x-pack/plugin/esql/qa/testFixtures/src/main/resources/date.csv-spec
@@ -1172,3 +1172,20 @@ from employees
 a:datetime
 null
 ;
+
+
+Least for dates
+required_capability: least_greatest_for_dates
+ROW a = LEAST(TO_DATETIME("1957-05-23T00:00:00Z"), TO_DATETIME("1958-02-19T00:00:00Z"));
+
+a:datetime
+1957-05-23T00:00:00
+;
+
+GREATEST for dates
+required_capability: least_greatest_for_dates
+ROW a = GREATEST(TO_DATETIME("1957-05-23T00:00:00Z"), TO_DATETIME("1958-02-19T00:00:00Z"));
+
+a:datetime
+1958-02-19T00:00:00
+;
diff --git a/x-pack/plugin/esql/qa/testFixtures/src/main/resources/meta.csv-spec b/x-pack/plugin/esql/qa/testFixtures/src/main/resources/meta.csv-spec
@@ -29,9 +29,9 @@ double e()
 "boolean ends_with(str:keyword|text, suffix:keyword|text)"
 "double|integer|long|unsigned_long floor(number:double|integer|long|unsigned_long)"
 "keyword from_base64(string:keyword|text)"
-"boolean|double|integer|ip|keyword|long|text|version greatest(first:boolean|double|integer|ip|keyword|long|text|version, ?rest...:boolean|double|integer|ip|keyword|long|text|version)"
+"boolean|date|double|integer|ip|keyword|long|text|version greatest(first:boolean|date|double|integer|ip|keyword|long|text|version, ?rest...:boolean|date|double|integer|ip|keyword|long|text|version)"
 "ip ip_prefix(ip:ip, prefixLengthV4:integer, prefixLengthV6:integer)"
-"boolean|double|integer|ip|keyword|long|text|version least(first:boolean|double|integer|ip|keyword|long|text|version, ?rest...:boolean|double|integer|ip|keyword|long|text|version)"
+"boolean|date|double|integer|ip|keyword|long|text|version least(first:boolean|date|double|integer|ip|keyword|long|text|version, ?rest...:boolean|date|double|integer|ip|keyword|long|text|version)"
 "keyword left(string:keyword|text, length:integer)"
 "integer length(string:keyword|text)"
 "integer locate(string:keyword|text, substring:keyword|text, ?start:integer)"
@@ -149,9 +149,9 @@ e             |null                                |null
 ends_with     |[str, suffix]                       |["keyword|text", "keyword|text"]                                                                                                  |[String expression. If `null`\, the function returns `null`., String expression. If `null`\, the function returns `null`.]
 floor         |number                              |"double|integer|long|unsigned_long"                                                                                               |Numeric expression. If `null`, the function returns `null`.
 from_base64   |string                              |"keyword|text"                                                                                                                    |A base64 string.
-greatest      |first                               |"boolean|double|integer|ip|keyword|long|text|version"                                                                             |First of the columns to evaluate.
+greatest      |first                               |"boolean|date|double|integer|ip|keyword|long|text|version"                                                                        |First of the columns to evaluate.
 ip_prefix     |[ip, prefixLengthV4, prefixLengthV6]|[ip, integer, integer]                                                                                                            |[IP address of type `ip` (both IPv4 and IPv6 are supported)., Prefix length for IPv4 addresses., Prefix length for IPv6 addresses.]
-least         |first                               |"boolean|double|integer|ip|keyword|long|text|version"                                                                             |First of the columns to evaluate.
+least         |first                               |"boolean|date|double|integer|ip|keyword|long|text|version"                                                                        |First of the columns to evaluate.
 left          |[string, length]                    |["keyword|text", integer]                                                                                                         |[The string from which to return a substring., The number of characters to return.]
 length        |string                              |"keyword|text"                                                                                                                    |String expression. If `null`, the function returns `null`.
 locate        |[string, substring, start]          |["keyword|text", "keyword|text", "integer"]                                                                                       |[An input string, A substring to locate in the input string, The start index]
@@ -392,9 +392,9 @@ e             |double
 ends_with     |boolean                                                                                                                     |[false, false]              |false           |false
 floor         |"double|integer|long|unsigned_long"                                                                                         |false                       |false           |false
 from_base64   |keyword                                                                                                                     |false                       |false           |false
-greatest      |"boolean|double|integer|ip|keyword|long|text|version"                                                                       |false                       |true            |false
+greatest      |"boolean|date|double|integer|ip|keyword|long|text|version"                                                                  |false                       |true            |false
 ip_prefix     |ip                                                                                                                          |[false, false, false]       |false           |false
-least         |"boolean|double|integer|ip|keyword|long|text|version"                                                                       |false                       |true            |false
+least         |"boolean|date|double|integer|ip|keyword|long|text|version"                                                                  |false                       |true            |false
 left          |keyword                                                                                                                     |[false, false]              |false           |false
 length        |integer                                                                                                                     |false                       |false           |false
 locate        |integer                                                                                                                     |[false, false, true]        |false           |false
diff --git a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java
@@ -168,6 +168,11 @@ public enum Cap {
          */
         FIXED_PUSHDOWN_PAST_PROJECT,
 
+        /**
+         * Support for datetime in least and greatest functions
+         */
+        LEAST_GREATEST_FOR_DATES,
+
         /**
          * Changed error messages for fields with conflicting types in different indices.
          */
diff --git a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/Greatest.java b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/Greatest.java
@@ -44,7 +44,7 @@ public class Greatest extends EsqlScalarFunction implements OptionalArgument {
     private DataType dataType;
 
     @FunctionInfo(
-        returnType = { "boolean", "double", "integer", "ip", "keyword", "long", "text", "version" },
+        returnType = { "boolean", "date", "double", "integer", "ip", "keyword", "long", "text", "version" },
         description = "Returns the maximum value from multiple columns. This is similar to <<esql-mv_max>>\n"
             + "except it is intended to run on multiple columns at once.",
         note = "When run on `keyword` or `text` fields, this returns the last string in alphabetical order. "
@@ -55,12 +55,12 @@ public Greatest(
         Source source,
         @Param(
             name = "first",
-            type = { "boolean", "double", "integer", "ip", "keyword", "long", "text", "version" },
+            type = { "boolean", "date", "double", "integer", "ip", "keyword", "long", "text", "version" },
             description = "First of the columns to evaluate."
         ) Expression first,
         @Param(
             name = "rest",
-            type = { "boolean", "double", "integer", "ip", "keyword", "long", "text", "version" },
+            type = { "boolean", "date", "double", "integer", "ip", "keyword", "long", "text", "version" },
             description = "The rest of the columns to evaluate.",
             optional = true
         ) List<Expression> rest
@@ -153,7 +153,7 @@ public ExpressionEvaluator.Factory toEvaluator(Function<Expression, ExpressionEv
         if (dataType == DataType.INTEGER) {
             return new GreatestIntEvaluator.Factory(source(), factories);
         }
-        if (dataType == DataType.LONG) {
+        if (dataType == DataType.LONG || dataType == DataType.DATETIME) {
             return new GreatestLongEvaluator.Factory(source(), factories);
         }
         if (dataType == DataType.KEYWORD
diff --git a/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/Least.java b/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/Least.java
@@ -44,7 +44,7 @@ public class Least extends EsqlScalarFunction implements OptionalArgument {
     private DataType dataType;
 
     @FunctionInfo(
-        returnType = { "boolean", "double", "integer", "ip", "keyword", "long", "text", "version" },
+        returnType = { "boolean", "date", "double", "integer", "ip", "keyword", "long", "text", "version" },
         description = "Returns the minimum value from multiple columns. "
             + "This is similar to <<esql-mv_min>> except it is intended to run on multiple columns at once.",
         examples = @Example(file = "math", tag = "least")
@@ -53,12 +53,12 @@ public Least(
         Source source,
         @Param(
             name = "first",
-            type = { "boolean", "double", "integer", "ip", "keyword", "long", "text", "version" },
+            type = { "boolean", "date", "double", "integer", "ip", "keyword", "long", "text", "version" },
             description = "First of the columns to evaluate."
         ) Expression first,
         @Param(
             name = "rest",
-            type = { "boolean", "double", "integer", "ip", "keyword", "long", "text", "version" },
+            type = { "boolean", "date", "double", "integer", "ip", "keyword", "long", "text", "version" },
             description = "The rest of the columns to evaluate.",
             optional = true
         ) List<Expression> rest
@@ -152,7 +152,7 @@ public ExpressionEvaluator.Factory toEvaluator(Function<Expression, ExpressionEv
         if (dataType == DataType.INTEGER) {
             return new LeastIntEvaluator.Factory(source(), factories);
         }
-        if (dataType == DataType.LONG) {
+        if (dataType == DataType.LONG || dataType == DataType.DATETIME) {
             return new LeastLongEvaluator.Factory(source(), factories);
         }
         if (dataType == DataType.KEYWORD
diff --git a/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/GreatestTests.java b/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/GreatestTests.java
@@ -100,6 +100,21 @@ public static Iterable<Object[]> parameters() {
                 )
             )
         );
+        suppliers.add(
+            new TestCaseSupplier(
+                "(a, b)",
+                List.of(DataType.DATETIME, DataType.DATETIME),
+                () -> new TestCaseSupplier.TestCase(
+                    List.of(
+                        new TestCaseSupplier.TypedData(1727877348000L, DataType.DATETIME, "a"),
+                        new TestCaseSupplier.TypedData(1727790948000L, DataType.DATETIME, "b")
+                    ),
+                    "GreatestLongEvaluator[values=[MvMax[field=Attribute[channel=0]], MvMax[field=Attribute[channel=1]]]]",
+                    DataType.DATETIME,
+                    equalTo(1727877348000L)
+                )
+            )
+        );
         return parameterSuppliersFromTypedData(anyNullIsNull(false, suppliers));
     }
 
diff --git a/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/LeastTests.java b/x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/scalar/conditional/LeastTests.java
@@ -99,6 +99,21 @@ public static Iterable<Object[]> parameters() {
                 )
             )
         );
+        suppliers.add(
+            new TestCaseSupplier(
+                "(a, b)",
+                List.of(DataType.DATETIME, DataType.DATETIME),
+                () -> new TestCaseSupplier.TestCase(
+                    List.of(
+                        new TestCaseSupplier.TypedData(1727877348000L, DataType.DATETIME, "a"),
+                        new TestCaseSupplier.TypedData(1727790948000L, DataType.DATETIME, "b")
+                    ),
+                    "LeastLongEvaluator[values=[MvMin[field=Attribute[channel=0]], MvMin[field=Attribute[channel=1]]]]",
+                    DataType.DATETIME,
+                    equalTo(1727790948000L)
+                )
+            )
+        );
         return parameterSuppliersFromTypedData(anyNullIsNull(false, suppliers));
     }
 
