From 65be29203b6bcbbdfc2040cbb614d03bfed568a9 Mon Sep 17 00:00:00 2001
From: Binh Vo <146007384+binhvomongodb@users.noreply.github.com>
Date: Wed, 6 Aug 2025 17:08:48 -0400
Subject: [PATCH] SERVER-108909 Readd jstests for mixed schema fix (#39732)

GitOrigin-RevId: 98494390a6fc09c85e216417054ce7f893168f17
---
 ...kports_required_for_multiversion_tests.yml |  4 +
 .../timeseries_insert_mixed_schema_docs.js    | 87 +++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 jstests/core/timeseries/write/timeseries_insert_mixed_schema_docs.js

diff --git a/etc/backports_required_for_multiversion_tests.yml b/etc/backports_required_for_multiversion_tests.yml
index 739bbe8cb54..895f997239f 100644
--- a/etc/backports_required_for_multiversion_tests.yml
+++ b/etc/backports_required_for_multiversion_tests.yml
@@ -466,6 +466,8 @@ last-continuous:
       ticket: SERVER-105874
     - test_file: jstests/sharding/query/lookup/union_with_doubly_nested_lookup.js
       ticket: SERVER-108341
+    - test_file: jstests/core/timeseries/write/timeseries_insert_mixed_schema_docs.js
+      ticket: SERVER-107361
   suites: null
 last-lts:
   all:
@@ -989,4 +991,6 @@ last-lts:
       ticket: SERVER-107352
     - test_file: jstests/sharding/query/lookup/union_with_doubly_nested_lookup.js
       ticket: SERVER-108341
+    - test_file: jstests/core/timeseries/write/timeseries_insert_mixed_schema_docs.js
+      ticket: SERVER-107361
   suites: null
diff --git a/jstests/core/timeseries/write/timeseries_insert_mixed_schema_docs.js b/jstests/core/timeseries/write/timeseries_insert_mixed_schema_docs.js
new file mode 100644
index 00000000000..85fd0ecfacf
--- /dev/null
+++ b/jstests/core/timeseries/write/timeseries_insert_mixed_schema_docs.js
@@ -0,0 +1,87 @@
+/**
+ * Tests directly inserting a time-series bucket with mixed schema.
+ *
+ * @tags: [
+ *   # $listCatalog does not include the tenant prefix in its results.
+ *   command_not_supported_in_serverless,
+ *   requires_timeseries,
+ *   does_not_support_viewless_timeseries_yet,
+ * ]
+ */
+
+import {TimeseriesTest} from "jstests/core/timeseries/libs/timeseries.js";
+import {getTimeseriesBucketsColl} from "jstests/core/timeseries/libs/viewless_timeseries_util.js";
+
+const testDB = db.getSiblingDB(jsTestName());
+const collName = "ts";
+
+/**
+ * Test 1: Basic insert of mixed schema, check bucket counts
+ */
+(function basicInsertMixedSchemaTest() {
+    assert.commandWorked(testDB.runCommand({drop: collName}));
+    assert.commandWorked(
+        testDB.createCollection(collName, {timeseries: {timeField: "t", metaField: "m"}}));
+    const coll = testDB[collName];
+
+    var doc = {
+        t: ISODate(),
+        m: "meta",
+        a: "foo",
+    };
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(1, coll.find({"m": "meta"}).toArray().length);
+    assert.eq(1, getTimeseriesBucketsColl(coll).find({}).toArray().length);
+
+    // new measurement, same bucket
+    doc.a = "bar";
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(2, coll.find({"m": "meta"}).toArray().length);
+    assert.eq(1, getTimeseriesBucketsColl(coll).find({"meta": "meta"}).toArray().length);
+
+    // new measurement, because schema changed, we have a new bucket
+    doc.a = 1;
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(3, coll.find({"m": "meta"}).toArray().length);
+    assert.eq(2, getTimeseriesBucketsColl(coll).find({"meta": "meta"}).toArray().length);
+
+    // new measurement, schema changed back, necessitating a third bucket
+    doc.a = "bam";
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(4, coll.find({"m": "meta"}).toArray().length);
+    // New measurement may go into new bucket, or prev bucket (reopened), but should not go into
+    // the recently created bucket.
+    assert.eq(1, getTimeseriesBucketsColl(coll).find({"meta": "meta"}).toArray()[1].control.count);
+})();
+
+/**
+ * Test 2: Test with very large docs, checks bug discovered in SERVER-107361
+ */
+(function largeDocInsertMixedSchemaTest() {
+    assert.commandWorked(testDB.runCommand({drop: collName}));
+    assert.commandWorked(
+        testDB.createCollection(collName, {timeseries: {timeField: "t", metaField: "m"}}));
+    const coll = testDB[collName];
+
+    var doc = {t: ISODate(), m: "meta", a: 1, payload: "small"};
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(1, coll.find({"m": "meta"}).toArray().length);
+    assert.eq(1, getTimeseriesBucketsColl(coll).find({}).toArray().length);
+
+    // new measurement, because schema changed, we have a new bucket
+    // previous bug would skip mixed schema check due to handling of large measurements
+    doc.a = "foo";
+    doc.payload = 'A'.repeat(130000);
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(2, coll.find({"m": "meta"}).toArray().length);
+    assert.eq(2, getTimeseriesBucketsColl(coll).find({"meta": "meta"}).toArray().length);
+
+    // new measurement, schema changed back, necessitating a third bucket
+    doc.a = 2;
+    doc.payload = "small";
+    assert.commandWorked(coll.insert(doc));
+    assert.eq(3, coll.find({"m": "meta"}).toArray().length);
+    // New measurement may go into new bucket, or prev bucket (reopened), but should not go into
+    // the recently created bucket.
+    assert.eq(1, getTimeseriesBucketsColl(coll).find({"meta": "meta"}).toArray()[1].control.count);
+})();