SERVER-57258: Add deprecation msg for mapReduce()

3 files changed, 153 insertions, 3 deletions

diff --git a/jstests/noPassthrough/deprecated_map_reduce.js b/jstests/noPassthrough/deprecated_map_reduce.js
new file mode 100644
index 00000000000..008e132cf90
--- /dev/null
+++ b/jstests/noPassthrough/deprecated_map_reduce.js
@@ -0,0 +1,134 @@
+// The map reduce command is deprecated in 5.0.
+//
+// In this test, we run the map reduce command multiple times.
+// We want to make sure that the deprecation warning message is only logged once despite
+// the multiple invocations in an effort to not clutter the dev's console.
+// More specifically, we expect to only log 1/127 of mapReduce() events.
+
+(function() {
+"use strict";
+load("jstests/libs/log.js");  // For findMatchingLogLine, findMatchingLogLines
+
+jsTest.log('Test standalone');
+const caseInsensitive = {
+    collation: {locale: "simple", strength: 2}
+};
+const standalone = MongoRunner.runMongod({});
+const dbName = 'test';
+const collName = "test_map_reduce_command_deprecation_messaging";
+const db = standalone.getDB(dbName);
+const coll = db.getCollection(collName);
+const fieldMatcher = {
+    msg:
+        "The map reduce command is deprecated. For more information, see https://docs.mongodb.com/manual/core/map-reduce/"
+};
+
+function mapFunc() {
+    emit(this.cust_id, this.amount);
+}
+function reduceFunc(key, values) {
+    return Array.sum(values);
+}
+
+coll.drop();
+assert.commandWorked(coll.insert({cust_id: "A", amount: 100, status: "B"}));
+assert.commandWorked(coll.insert({cust_id: "A", amount: 200, status: "B"}));
+assert.commandWorked(coll.insert({cust_id: "B", amount: 50, status: "B"}));
+
+// Assert that deprecation msg is not logged before map reduce command is even run.
+var globalLogs = db.adminCommand({getLog: 'global'});
+var matchingLogLines = [...findMatchingLogLines(globalLogs.log, fieldMatcher)];
+assert.eq(matchingLogLines.length, 0, matchingLogLines);
+
+assert.commandWorked(db.runCommand(
+    {mapReduce: collName, map: mapFunc, reduce: reduceFunc, query: {b: 2}, out: "order_totals"}));
+
+assert.commandWorked(coll.insert({cust_id: "B", amount: 50, status: "B"}));
+
+assert.commandWorked(db.runCommand(
+    {mapReduce: collName, map: mapFunc, reduce: reduceFunc, query: {b: 2}, out: "order_totals"}));
+
+assert.commandWorked(coll.insert({cust_id: "A", amount: 200, status: "B"}));
+
+assert.commandWorked(db.runCommand(
+    {mapReduce: collName, map: mapFunc, reduce: reduceFunc, query: {"B": 2}, out: "order_totals"}));
+
+// Now that we have ran map reduce command, make sure the deprecation message is logged once.
+globalLogs = db.adminCommand({getLog: 'global'});
+matchingLogLines = [...findMatchingLogLines(globalLogs.log, fieldMatcher)];
+assert.eq(matchingLogLines.length, 1, matchingLogLines);
+MongoRunner.stopMongod(standalone);
+
+jsTest.log('Test cluster');
+
+const st = new ShardingTest({shards: 2, mongos: 1});
+
+const session = st.s.getDB("test").getMongo().startSession();
+const mongosDB = session.getDatabase("test");
+const mongosColl = mongosDB.testing;
+
+mongosColl.drop();
+assert.commandWorked(mongosDB.createCollection(mongosColl.getName(), caseInsensitive));
+
+assert.commandWorked(mongosColl.insert({cust_id: "A", amount: 100, status: "B"}));
+assert.commandWorked(mongosColl.insert({cust_id: "A", amount: 200, status: "B"}));
+assert.commandWorked(mongosColl.insert({cust_id: "B", amount: 50, status: "B"}));
+assert.commandWorked(mongosColl.insert({cust_id: "A", amount: 10, status: "B"}));
+assert.commandWorked(mongosColl.insert({cust_id: "A", amount: 20, status: "B"}));
+assert.commandWorked(mongosColl.insert({cust_id: "B", amount: 5, status: "B"}));
+
+assert.commandWorked(st.s0.adminCommand({enableSharding: mongosDB.getName()}));
+st.ensurePrimaryShard(db.getName(), st.shard0.shardName);
+assert.commandWorked(
+    st.s0.adminCommand({shardCollection: mongosColl.getFullName(), key: {_id: 1}}));
+
+// Assert that deprecation msg is not logged before map reduce command is even run.
+globalLogs = mongosDB.adminCommand({getLog: 'global'});
+matchingLogLines = [...findMatchingLogLines(globalLogs.log, fieldMatcher)];
+assert.eq(matchingLogLines.length, 0, matchingLogLines);
+
+// Check the logs of the primary shard of the mongos.
+globalLogs = st.shard0.getDB("test").adminCommand({getLog: 'global'});
+matchingLogLines = [...findMatchingLogLines(globalLogs.log, fieldMatcher)];
+assert.eq(matchingLogLines.length, 0, matchingLogLines);
+
+assert.commandWorked(mongosDB.runCommand({
+    mapReduce: mongosColl.getName(),
+    map: mapFunc,
+    reduce: reduceFunc,
+    query: {b: 2},
+    out: "order_totals"
+}));
+
+assert.commandWorked(mongosColl.insert({cust_id: "B", amount: 50, status: "B"}));
+
+assert.commandWorked(mongosDB.runCommand({
+    mapReduce: mongosColl.getName(),
+    map: mapFunc,
+    reduce: reduceFunc,
+    query: {b: 2},
+    out: "order_totals"
+}));
+
+assert.commandWorked(mongosColl.insert({cust_id: "A", amount: 200, status: "B"}));
+
+assert.commandWorked(mongosDB.runCommand({
+    mapReduce: mongosColl.getName(),
+    map: mapFunc,
+    reduce: reduceFunc,
+    query: {"B": 2},
+    out: "order_totals"
+}));
+
+// Now that we have ran map reduce command, make sure the deprecation message is logged once.
+globalLogs = mongosDB.adminCommand({getLog: 'global'});
+matchingLogLines = [...findMatchingLogLines(globalLogs.log, fieldMatcher)];
+assert.eq(matchingLogLines.length, 1, matchingLogLines);
+
+// Check the logs of the primary shard of the mongos.
+globalLogs = st.shard0.getDB("test").adminCommand({getLog: 'global'});
+matchingLogLines = [...findMatchingLogLines(globalLogs.log, fieldMatcher)];
+assert.eq(matchingLogLines.length, 0, matchingLogLines);
+
+st.stop();
+})();
diff --git a/src/mongo/db/commands/map_reduce_agg.cpp b/src/mongo/db/commands/map_reduce_agg.cpp
index 43a66fb2314..b75a18a4a77 100644
--- a/src/mongo/db/commands/map_reduce_agg.cpp
+++ b/src/mongo/db/commands/map_reduce_agg.cpp
@@ -26,7 +26,7 @@
  *    exception statement from all source files in the program, then also delete
  *    it in the license file.
  */
-
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kCommand
 #include "mongo/platform/basic.h"
 
 #include <boost/intrusive_ptr.hpp>
@@ -53,10 +53,12 @@
 #include "mongo/db/query/explain_common.h"
 #include "mongo/db/query/map_reduce_output_format.h"
 #include "mongo/db/query/plan_executor_factory.h"
+#include "mongo/logv2/log.h"
 
 namespace mongo::map_reduce_agg {
 
 namespace {
+Rarely _sampler;
 
 auto makeExpressionContext(OperationContext* opCtx,
                            const MapReduceCommandRequest& parsedMr,
@@ -112,6 +114,13 @@ bool runAggregationMapReduce(OperationContext* opCtx,
                              const BSONObj& cmd,
                              BSONObjBuilder& result,
                              boost::optional<ExplainOptions::Verbosity> verbosity) {
+
+    if (_sampler.tick()) {
+        LOGV2_WARNING(5725801,
+                      "The map reduce command is deprecated. For more information, see "
+                      "https://docs.mongodb.com/manual/core/map-reduce/");
+    }
+
     auto exhaustPipelineIntoBSONArray = [](auto&& exec) {
         BSONArrayBuilder bab;
         BSONObj obj;
diff --git a/src/mongo/s/commands/cluster_map_reduce_agg.cpp b/src/mongo/s/commands/cluster_map_reduce_agg.cpp
index 9d16d22513f..7cba5b51bd5 100644
--- a/src/mongo/s/commands/cluster_map_reduce_agg.cpp
+++ b/src/mongo/s/commands/cluster_map_reduce_agg.cpp
@@ -26,7 +26,7 @@
  *    exception statement from all source files in the program, then also delete
  *    it in the license file.
  */
-
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kCommand
 #include "mongo/platform/basic.h"
 
 #include "mongo/bson/bsonobj.h"
@@ -47,6 +47,7 @@
 #include "mongo/db/query/explain_common.h"
 #include "mongo/db/query/getmore_request.h"
 #include "mongo/db/query/map_reduce_output_format.h"
+#include "mongo/logv2/log.h"
 #include "mongo/s/catalog_cache.h"
 #include "mongo/s/cluster_commands_helpers.h"
 #include "mongo/s/commands/cluster_map_reduce_agg.h"
@@ -55,7 +56,7 @@
 
 namespace mongo {
 namespace {
-
+Rarely _sampler;
 auto makeExpressionContext(OperationContext* opCtx,
                            const MapReduceCommandRequest& parsedMr,
                            const ChunkManager& cm,
@@ -152,6 +153,12 @@ bool runAggregationMapReduce(OperationContext* opCtx,
     auto resolvedOutNss = NamespaceString{hasOutDB ? *hasOutDB : parsedMr.getNamespace().db(),
                                           parsedMr.getOutOptions().getCollectionName()};
 
+    if (_sampler.tick()) {
+        LOGV2_WARNING(5725800,
+                      "The map reduce command is deprecated. For more information, see "
+                      "https://docs.mongodb.com/manual/core/map-reduce/");
+    }
+
     if (parsedMr.getOutOptions().getOutputType() != OutputType::InMemory) {
         involvedNamespaces.insert(resolvedOutNss);
     }