SERVER-47773 Error consistently when tailable cursors and $near are u…

…sed together

(cherry picked from commit c8ced6d)
(cherry picked from commit e9c31e7)

etc/backports_required_for_multiversion_tests.yml

@@ -31,6 +31,8 @@ replica_sets_jscore_multiversion_passthrough:
   test_file: jstests/core/txns/new_transaction_waits_for_previous_txn_table_updates.js
 - ticket: SERVER-40805
   test_file: jstests/core/profile_find.js
+- ticket: SERVER-47773
+  test_file: jstests/core/geo_near_tailable.js
 
 replica_sets_multiversion:
 - ticket: SERVER-42825
@@ -65,5 +67,9 @@ sharding_multiversion:
   test_file: jstests/sharding/retryable_writes.js
 
 sharding_jscore_multiversion_passthrough:
+- ticket: SERVER-47773
+  test_file: jstests/core/geo_near_tailable.js
 
 sharded_collections_jscore_multiversion_passthrough:
+- ticket: SERVER-47773
+  test_file: jstests/core/geo_near_tailable.js

jstests/core/geo_near_tailable.js

@@ -0,0 +1,25 @@
+// @tags: [requires_capped]
+//
+// Tests that combine $geoNear and tailable cursors.
+//
+(function() {
+"use strict";
+
+let cmdRes;
+const collName = 'geo_near_tailable';
+const cappedCollName = 'geo_near_tailable_capped';
+
+// Avoid using the drop() shell helper here in order to avoid "implicit collection recreation"
+// which can happen when this test runs in certain passthroughs. For details, see
+// "jstests/libs/override_methods/implicitly_shard_accessed_collections.js".
+db.runCommand({drop: collName});
+db.runCommand({drop: cappedCollName});
+assert.commandWorked(db.createCollection(collName));
+assert.commandWorked(db.createCollection(cappedCollName, {capped: true, size: 10000}));
+
+// Error when tailable option is used with NEAR.
+cmdRes = db.runCommand({find: collName, filter: {a: {$geoNear: [1, 2]}}, tailable: true});
+assert.commandFailedWithCode(cmdRes, ErrorCodes.BadValue);
+cmdRes = db.runCommand({find: cappedCollName, filter: {a: {$geoNear: [1, 2]}}, tailable: true});
+assert.commandFailedWithCode(cmdRes, ErrorCodes.BadValue);
+})();

src/mongo/db/query/canonical_query.cpp

@@ -409,6 +409,12 @@ Status CanonicalQuery::isValid(MatchExpression* root, const QueryRequest& parsed
         return Status(ErrorCodes::BadValue, "text and tailable cursor not allowed in same query");
     }
 
+    // NEAR and tailable are incompatible.
+    if (numGeoNear > 0 && parsed.isTailable()) {
+        return Status(ErrorCodes::BadValue,
+                      "Tailable cursors and geo $near cannot be used together");
+    }
+
     // $natural sort order must agree with hint.
     if (sortNaturalElt) {
         if (!hintObj.isEmpty() && !hintNaturalElt) {

src/mongo/db/query/query_planner.cpp

@@ -550,7 +550,7 @@ StatusWith<std::vector<std::unique_ptr<QuerySolution>>> QueryPlanner::plan(
     // If the query requests a tailable cursor, the only solution is a collscan + filter with
     // tailable set on the collscan.
     if (isTailable) {
-        if (!QueryPlannerCommon::hasNode(query.root(), MatchExpression::GEO_NEAR) && canTableScan) {
+        if (canTableScan) {
             auto soln = buildCollscanSoln(query, isTailable, params);
             if (soln) {
                 out.push_back(std::move(soln));