diff --git a/daggy/include/daggy/Task.hpp b/daggy/include/daggy/Task.hpp
index da6323b..cdf15e0 100644
--- a/daggy/include/daggy/Task.hpp
+++ b/daggy/include/daggy/Task.hpp
@@ -3,6 +3,7 @@
 #include <cstdint>
 #include <string>
 #include <vector>
+#include <unordered_set>
 
 namespace daggy {
     struct Task {
@@ -10,6 +11,6 @@ namespace daggy {
         std::vector<std::string> command;
         uint32_t maxRetries;
         uint32_t retryIntervalSeconds; // Time to wait between retries
-        std::vector<std::string> children;
+        std::unordered_set<std::string> children;
     };
 }
diff --git a/daggy/src/Serialization.cpp b/daggy/src/Serialization.cpp
index 6b3a0d1..e9c31b6 100644
--- a/daggy/src/Serialization.cpp
+++ b/daggy/src/Serialization.cpp
@@ -87,11 +87,11 @@ namespace daggy {
                     "retryIntervalSeconds")) { retryIntervalSeconds = taskSpec["retryIntervalSeconds"].GetInt(); }
 
             // Children / parents
-            std::vector<std::string> children;
+            std::unordered_set<std::string> children;
             if (taskSpec.HasMember("children")) {
                 const auto &specChildren = taskSpec["children"].GetArray();
                 for (size_t c = 0; c < specChildren.Size(); ++c) {
-                    children.emplace_back(specChildren[c].GetString());
+                    children.insert(specChildren[c].GetString());
                 }
             }
             if (taskSpec.HasMember("parents")) {
@@ -129,16 +129,16 @@ namespace daggy {
             if (pit == parentMap.end()) { continue; }
 
             for (const auto &parent : pit->second) {
-                tasks[taskIndex[parent]].children.emplace_back(task.name);
+                tasks[taskIndex[parent]].children.insert(task.name);
             }
         }
 
         // At the end, replace the names of the children with all the expanded versions
         for (auto &task : tasks) {
-            std::vector<std::string> children;
+            std::unordered_set<std::string> children;
             for (const auto &child : task.children) {
                 auto &newChildren = childrenMap[child];
-                std::copy(newChildren.begin(), newChildren.end(), std::back_inserter(children));
+                std::copy(newChildren.begin(), newChildren.end(), std::inserter(children, children.end()));
             }
             task.children.swap(children);
         }
@@ -150,6 +150,8 @@ namespace daggy {
     // So we'll shortcut and generate the JSON directly.
     std::string taskToJSON(const Task &task) {
         std::stringstream ss;
+        bool first = false;
+
         ss << "{"
            << R"("name": )" << std::quoted(task.name) << ','
            << R"("maxRetries": )" << task.maxRetries << ','
@@ -157,16 +159,20 @@ namespace daggy {
 
         // Commands
         ss << R"("command": [)";
-        for (auto it = task.command.begin(); it != task.command.end(); ++it) {
-            ss << std::quoted(*it);
-            if (it != task.command.end() - 1) ss << ", ";
+        first = true;
+        for (const auto &part : task.command) {
+            if (!first) ss << ',';
+            ss << std::quoted(part);
+            first = false;
         }
         ss << "],";
 
         ss << R"("children": [)";
-        for (auto it = task.children.begin(); it != task.children.end(); ++it) {
-            ss << std::quoted(*it);
-            if (it != task.children.end() - 1) ss << ", ";
+        first = true;
+        for (const auto &child : task.children) {
+            if (!first) ss << ',';
+            ss << std::quoted(child);
+            first = false;
         }
         ss << "]";
 
@@ -179,9 +185,11 @@ namespace daggy {
 
         ss << "[";
 
-        for (auto it = tasks.begin(); it != tasks.end(); ++it) {
-            ss << taskToJSON(*it);
-            if (it != tasks.end() - 1) ss << ", ";
+        bool first = true;
+        for (const auto &task : tasks) {
+            if (!first) ss << ',';
+            ss << taskToJSON(task);
+            first = false;
         }
         ss << "]";
 
diff --git a/daggy/src/loggers/dag_run/FileSystemLogger.cpp b/daggy/src/loggers/dag_run/FileSystemLogger.cpp
index 9ee4065..c4e6e77 100644
--- a/daggy/src/loggers/dag_run/FileSystemLogger.cpp
+++ b/daggy/src/loggers/dag_run/FileSystemLogger.cpp
@@ -44,6 +44,7 @@ namespace daggy {
         fs::create_directories(runRoot);
 
         // Create meta.json with DAGRun Name and task definitions
+        return runID;
     }
 
     void FileSystemLogger::updateDAGRunState(DAGRunID dagRunID, RunState state) {}
@@ -53,7 +54,7 @@ namespace daggy {
     void FileSystemLogger::updateTaskState(DAGRunID dagRunID, TaskID taskID, RunState state) {}
 
     // Querying
-    std::vector<DAGRunSummary> FileSystemLogger::getDAGs(uint32_t stateMask) {}
+    std::vector<DAGRunSummary> FileSystemLogger::getDAGs(uint32_t stateMask) { return {}; }
 
-    DAGRunRecord FileSystemLogger::getDAGRun(DAGRunID dagRunID) {}
+    DAGRunRecord FileSystemLogger::getDAGRun(DAGRunID dagRunID) { return {}; }
 }