perf: Adds Gatling performance test for aggregate data export with descendants [DHIS2-21490] (#23895)

* perf: add Gatling performance test for aggregate data export with descendants [DHIS2-21490]

Adds AggregateDataExportPerformanceTest covering GET /api/dataValueSets/ with
children=true against the Sierra Leone demo database — the exact scenario that
exposed the O(n²) org unit descendants cross-join fixed in DHIS2-21490.

Uses Sierra Leone root org unit and ART monthly summary dataset with a rolling
two-year date window, 5 concurrent users over 10 seconds.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Add aggregate data export with descendats performance test

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: jason-p-pickering

dhis-2/dhis-test-performance/src/test/java/org/hisp/dhis/test/platform/AggregateDataExportPerformanceTest.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2004-2025, University of Oslo
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors 
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.hisp.dhis.test.platform;
+
+import static io.gatling.javaapi.core.CoreDsl.*;
+import static io.gatling.javaapi.http.HttpDsl.*;
+
+import io.gatling.javaapi.core.ClosedInjectionStep;
+import io.gatling.javaapi.core.ScenarioBuilder;
+import io.gatling.javaapi.core.Simulation;
+import io.gatling.javaapi.http.HttpProtocolBuilder;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+
+/**
+ * Performance test for data value set export with org unit descendants (DHIS2-21490).
+ *
+ * <p>Exercises {@code GET /api/dataValueSets/} with {@code children=true}, which activates the
+ * {@code ou_with_descendants_ids} CTE in {@code HibernateDataExportStore}. The original query used
+ * an O(n²) self-join across the entire org unit table; the fix drives from the selected roots and
+ * uses the {@code varchar_pattern_ops} path index to find descendants in O(roots × log n).
+ *
+ * <p>Assumes a Sierra Leone demo database at {@code localhost:8080}. UIDs are stable across demo
+ * database versions:
+ *
+ * <ul>
+ *   <li>Sierra Leone root org unit: {@code ImspTQPwCqd}
+ *   <li>ART monthly summary dataset: {@code lyLU2wR22tC}
+ * </ul>
+ */
+public class AggregateDataExportPerformanceTest extends Simulation {
+
+  private static final String BASE_URL = "http://localhost:8080";
+  private static final String EXPORT_REQUEST = "GET dataValueSets - root OU with descendants";
+
+  @Override
+  public void before() {
+    MetadataImporter.importJsonFile("platform/superuser-data-sl-db.json", "admin", "district");
+  }
+
+  public AggregateDataExportPerformanceTest() {
+    DateTimeFormatter fmt = DateTimeFormatter.ISO_LOCAL_DATE;
+    String endDate = LocalDate.now().format(fmt);
+    String startDate = LocalDate.now().minusYears(2).format(fmt);
+
+    HttpProtocolBuilder httpProtocol =
+        http.baseUrl(BASE_URL)
+            .acceptHeader("application/json")
+            .warmUp(BASE_URL + "/api/ping")
+            .disableCaching()
+            .basicAuth("admin", "district");
+
+    ScenarioBuilder exportScenario =
+        scenario(EXPORT_REQUEST)
+            .group(EXPORT_REQUEST)
+            .on(
+                repeat(1)
+                    .on(
+                        exec(http(EXPORT_REQUEST)
+                                .get("/api/dataValueSets/")
+                                .queryParam("orgUnit", "ImspTQPwCqd")
+                                .queryParam("children", "true")
+                                .queryParam("dataSet", "lyLU2wR22tC")
+                                .queryParam("startDate", startDate)
+                                .queryParam("endDate", endDate))
+                            .pause(1)));
+
+    ClosedInjectionStep closedInjection = rampConcurrentUsers(0).to(5).during(10);
+
+    setUp(exportScenario.injectClosed(closedInjection))
+        .protocols(httpProtocol)
+        .assertions(
+            details(EXPORT_REQUEST).responseTime().percentile(95).lt(300),
+            details(EXPORT_REQUEST).responseTime().max().lt(500),
+            details(EXPORT_REQUEST).successfulRequests().percent().is(100D));
+  }
+}