From 5f4d43f877a1aee5320a80cf3c1a885c103ddf76 Mon Sep 17 00:00:00 2001
From: Kishore Nallan <kishorenc@gmail.com>
Date: Sat, 18 Feb 2023 14:28:43 +0530
Subject: [PATCH 1/2] The `id` cannot be a default sorting field.

---
 include/field.h                  |  2 +-
 src/collection_manager.cpp       |  4 ++++
 test/collection_sorting_test.cpp | 17 +++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/include/field.h b/include/field.h
index 35813c95..c8ba94b0 100644
--- a/include/field.h
+++ b/include/field.h
@@ -355,7 +355,7 @@ struct field {
             }
         }
 
-        if(!default_sorting_field.empty() && !found_default_sorting_field && !fields.empty()) {
+        if(!default_sorting_field.empty() && !found_default_sorting_field) {
             return Option<bool>(400, "Default sorting field is defined as `" + default_sorting_field +
                                      "` but is not found in the schema.");
         }
diff --git a/src/collection_manager.cpp b/src/collection_manager.cpp
index 126d4824..ec95d1db 100644
--- a/src/collection_manager.cpp
+++ b/src/collection_manager.cpp
@@ -1130,6 +1130,10 @@ Option<Collection*> CollectionManager::create_collection(nlohmann::json& req_jso
 
     const std::string& default_sorting_field = req_json[DEFAULT_SORTING_FIELD].get<std::string>();
 
+    if(default_sorting_field == "id") {
+        return Option<Collection *>(400, "Invalid `default_sorting_field` value: cannot be `id`.");
+    }
+
     std::string fallback_field_type;
     std::vector<field> fields;
     auto parse_op = field::json_fields_to_fields(req_json[ENABLE_NESTED_FIELDS].get<bool>(),
diff --git a/test/collection_sorting_test.cpp b/test/collection_sorting_test.cpp
index 8bd805a9..121a0e64 100644
--- a/test/collection_sorting_test.cpp
+++ b/test/collection_sorting_test.cpp
@@ -2147,6 +2147,23 @@ TEST_F(CollectionSortingTest, OptionalFilteringViaSortingSearch) {
     collectionManager.drop_collection("coll1");
 }
 
+TEST_F(CollectionSortingTest, DisallowIdAsDefaultSortingField) {
+    std::string coll_schema = R"(
+        {
+            "name": "coll1",
+            "default_sorting_field": "id",
+            "fields": [
+              {"name": "id", "type": "string" }
+            ]
+        }
+    )";
+
+    nlohmann::json schema = nlohmann::json::parse(coll_schema);
+    auto coll_op = collectionManager.create_collection(schema);
+    ASSERT_FALSE(coll_op.ok());
+    ASSERT_EQ("Invalid `default_sorting_field` value: cannot be `id`.", coll_op.error());
+}
+
 TEST_F(CollectionSortingTest, OptionalFilteringViaSortingSecondThirdParams) {
     std::string coll_schema = R"(
         {

From e80b17085a27321b77fb02c02e8e9de79c394539 Mon Sep 17 00:00:00 2001
From: Kishore Nallan <kishorenc@gmail.com>
Date: Mon, 20 Feb 2023 18:10:22 +0530
Subject: [PATCH 2/2] Allow sequence id based sorting.

---
 src/collection.cpp               |  3 ++-
 test/collection_sorting_test.cpp | 26 ++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/collection.cpp b/src/collection.cpp
index db5f9046..35a7a697 100644
--- a/src/collection.cpp
+++ b/src/collection.cpp
@@ -722,7 +722,8 @@ Option<bool> Collection::validate_and_standardize_sort_fields(const std::vector<
             }
         }
 
-        if (sort_field_std.name != sort_field_const::text_match && sort_field_std.name != sort_field_const::eval) {
+        if (sort_field_std.name != sort_field_const::text_match && sort_field_std.name != sort_field_const::eval &&
+            sort_field_std.name != sort_field_const::seq_id) {
             const auto field_it = search_schema.find(sort_field_std.name);
             if(field_it == search_schema.end() || !field_it.value().sort || !field_it.value().index) {
                 std::string error = "Could not find a field named `" + sort_field_std.name +
diff --git a/test/collection_sorting_test.cpp b/test/collection_sorting_test.cpp
index 121a0e64..99cb95c7 100644
--- a/test/collection_sorting_test.cpp
+++ b/test/collection_sorting_test.cpp
@@ -1952,6 +1952,32 @@ TEST_F(CollectionSortingTest, DisallowSortingOnNonIndexedIntegerField) {
     collectionManager.drop_collection("coll1");
 }
 
+TEST_F(CollectionSortingTest, WildcardSearchSequenceIdSort) {
+    nlohmann::json schema = R"({
+        "name": "coll1",
+        "fields": [
+            {"name": "category", "type": "string"}
+        ]
+    })"_json;
+
+    Collection* coll1 = collectionManager.create_collection(schema).get();
+
+    nlohmann::json doc;
+    doc["category"] = "Shoes";
+
+    for(size_t i = 0; i < 30; i++) {
+        ASSERT_TRUE(coll1->add(doc.dump()).ok());
+    }
+
+    std::vector<sort_by> sort_fields = {
+        sort_by("_seq_id", "DESC"),
+    };
+
+    auto res = coll1->search("*", {"category"}, "", {}, sort_fields, {2}, 10, 1, FREQUENCY, {true}, 0).get();
+    ASSERT_EQ(10, res["hits"].size());
+    ASSERT_EQ(30, res["found"].get<size_t>());
+}
+
 TEST_F(CollectionSortingTest, OptionalFilteringViaSortingWildcard) {
     std::string coll_schema = R"(
         {