Propagate filter in TOP(field, 1, order) surrogate.

Author: jan-elastic

x-pack/plugin/esql/qa/testFixtures/src/main/resources/data/sample.py

@@ -0,0 +1,24 @@
+from random import random
+
+for N in [1, 10, 100, 1000]:
+
+  avgs = []
+
+  for i in range(10000):
+    s = 0
+    c = 0
+
+    for j in range(N):
+      if random() < 0.5:
+        s += 1
+        c += 1
+      if random() < 0.5:
+        s += 2+3
+        c += 2
+
+      if c > 0:
+        avgs.append(s/c)
+
+  avg = sum(avgs) / len(avgs)
+  err = (sum((x - avg) ** 2 for x in avgs) ** 0.5 / len(avgs))
+  print(N, avg, '+/-', err)

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

@@ -300,3 +300,17 @@ FROM books
                                                     The Lord of the Rings Poster Collection: Six Paintings by Alan Lee (No. 1) | he Lo |                                                                [J. R. R. Tolkien, Alan Lee] | Alan Lee
 A Gentle Creature and Other Stories: White Nights, A Gentle Creature, and The Dream of a Ridiculous Man (The World's Classics) |  Gent |                                        [W. J. Leatherbarrow, Fyodor Dostoevsky, Alan Myers] | Alan Myers
 ;
+
+topWithConditions
+required_capability: stats_top_1_with_condition_fixed
+
+FROM employees
+| STATS min1 = TOP(emp_no, 1, "ASC") WHERE emp_no > 10010,
+        min2 = TOP(emp_no, 2, "ASC") WHERE emp_no > 10010,
+        max1 = TOP(emp_no, 1, "DESC") WHERE emp_no < 10080,
+        max2 = TOP(emp_no, 2, "DESC") WHERE emp_no < 10080
+;
+
+min1:integer | min2:integer   | max1:integer | max2:integer
+10011        | [10011, 10012] | 10079        | [10079, 10078]
+;

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

@@ -289,9 +289,9 @@ public Expression surrogate() {
         var s = source();
         if (orderField() instanceof Literal && limitField() instanceof Literal && limitValue() == 1) {
             if (orderValue()) {
-                return new Min(s, field());
+                return new Min(s, field(), filter());
             } else {
-                return new Max(s, field());
+                return new Max(s, field(), filter());
             }
         }
         return null;