Some fixes

Author: jan-elastic

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/aggregation/ChangePointStates.java

@@ -124,7 +124,8 @@ private Block buildValuesBlock(BlockFactory blockFactory) {
 
         // TODO: this needs to output multiple columns or a composite object, not a JSON blob.
         private BytesRef getChangePoint() {
-            // TODO: this copying doesn't account for memory
+            // TODO: probably reuse ES|QL sort/orderBy to get results in order
+            // TODO: this copying/sorting doesn't account for memory
             List<TimeAndValue> list = new ArrayList<>(count);
             for (int i = 0; i < count; i++) {
                 list.add(new TimeAndValue(timestamps.get(i), values.get(i)));

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/aggregate/ChangePoint.java

@@ -40,7 +40,7 @@ public class ChangePoint extends AggregateFunction implements OptionalArgument,
         ChangePoint::new
     );
 
-    @FunctionInfo(returnType = { "string" }, description = "...", isAggregation = true)
+    @FunctionInfo(returnType = { "string" }, description = "Detects spikes, dips, and change points in a metric", isAggregation = true)
     public ChangePoint(
         Source source,
         @Param(name = "field", type = { "double", "integer", "long" }, description = "field") Expression field,
@@ -73,12 +73,16 @@ Expression timestamp() {
 
     @Override
     protected NodeInfo<ChangePoint> info() {
-        return NodeInfo.create(this, ChangePoint::new, field(), timestamp());
+        return NodeInfo.create(this, ChangePoint::new, field(), filter(), timestamp());
     }
 
     @Override
     public ChangePoint replaceChildren(List<Expression> newChildren) {
-        return new ChangePoint(source(), newChildren.get(0), newChildren.get(1), newChildren.get(2));
+        if (newChildren.size() == 2) {
+            return new ChangePoint(source(), newChildren.get(0), newChildren.get(1));
+        } else {
+            return new ChangePoint(source(), newChildren.get(0), newChildren.get(1), newChildren.get(2));
+        }
     }
 
     // TODO: this needs to output multiple columns or a composite object

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/esql/60_usage.yml

@@ -92,7 +92,7 @@ setup:
   - gt: {esql.functions.to_long: $functions_to_long}
   - match: {esql.functions.coalesce: $functions_coalesce}
   # Testing for the entire function set isn't feasbile, so we just check that we return the correct count as an approximation.
-  - length: {esql.functions: 130} # check the "sister" test below for a likely update to the same esql.functions length check
+  - length: {esql.functions: 131} # check the "sister" test below for a likely update to the same esql.functions length check
 
 ---
 "Basic ESQL usage output (telemetry) non-snapshot version":