diff --git a/engine/types.py b/engine/types.py
index d99fc56..de80c7d 100644
--- a/engine/types.py
+++ b/engine/types.py
@@ -248,7 +248,7 @@ def count_behavior(op:OperatorBase, c_code, x, distinct = False):
     if not c_code:
         return f'{op.sqlname}({"distinct " if distinct else ""}{x})'
     elif distinct:
-        return 'count_'+base62uuid()
+        return '({x}).distinct_size()'
     else:
         return '{count()}'
 
diff --git a/reconstruct/expr.py b/reconstruct/expr.py
index 91ed2f9..ce5ea4f 100644
--- a/reconstruct/expr.py
+++ b/reconstruct/expr.py
@@ -94,6 +94,7 @@ class expr(ast_node):
                     print(f'Parser Error: {node} has more than 1 dict entry.')
                 
                 for key, val in node.items():
+                    key = key.lower()
                     if key in self.operators:
                         if key in builtin_func:
                             if self.is_agg_func:
@@ -121,9 +122,9 @@ class expr(ast_node):
                         try:
                             self.type = op.return_type(*type_vals)
                         except AttributeError as e:
-                            if type(self.root) is not udf:
+                            if type(self.root.parent) is not udf:
                                 # TODO: do something when this is not an error
-                                # print(f'alert: {e}')
+                                print(f'alert: {e}')
                                 pass
                             self.type = AnyT
                             
@@ -198,7 +199,11 @@ class expr(ast_node):
                                 self.udf_decltypecall = ex_vname.sql
                     else:
                         print(f'Undefined expr: {key}{val}')
-
+            if 'distinct' in val and key != count:
+                if self.c_code:
+                    self.sql = 'distinct ' + self.sql
+                elif self.is_compound:
+                    self.sql = '(' + self.sql + ').distinct()' 
         if type(node) is str:
             if self.is_udfexpr:
                 curr_udf : udf = self.root.udf
@@ -395,4 +400,4 @@ class getrefs(expr):
     def consume(self, _):
         if self.root == self:
             self.rec = self.datasource.rec
-            self.datasource.rec = None
\ No newline at end of file
+            self.datasource.rec = None
diff --git a/server/table.h b/server/table.h
index 36b653a..f96c0e6 100644
--- a/server/table.h
+++ b/server/table.h
@@ -139,7 +139,9 @@ public:
 		const ColRef<_Ty>& orig;
 		constexpr Iterator_t(const uint32_t* val, const ColRef<_Ty>& orig) noexcept : val(val), orig(orig) {}
 		_Ty& operator*() { return orig[*val]; }
-		bool operator != (const Iterator_t& rhs) { return rhs.val != val; }
+		bool operator != (const Iterator_t& rhs) const { return rhs.val != val; }
+		bool operator == (const Iterator_t& rhs) const { return rhs.val == val; }
+		size_t operator - (const Iterator_t& rhs) const { return val - rhs.val; }
 		Iterator_t& operator++ () {
 			++val;
 			return *this;
@@ -180,6 +182,20 @@ public:
 			subvec[i] = operator[](i);
 		return subvec;
 	}
+	std::unordered_set<_Ty> distinct_common() {
+		return std::unordered_set<_Ty> {begin(), end()};
+	}
+	uint32_t distinct_size(){
+		return distinct_common().size();
+	}
+	ColRef<_Ty> distinct(){
+		auto set = distinct_common();
+		ColRef<_Ty> ret(set.size());
+		uint32_t i = 0;
+		for (auto& val : set)
+			ret.container[i++] = val;
+		return ret;
+	}
 	inline ColRef<_Ty> subvec(uint32_t start = 0) { return subvec_deep(start, size); }
 };
 template <template <class...> class VT, class T>
@@ -408,10 +424,43 @@ struct TableInfo {
 		applyIntegerSequence<sizeof...(Types), applier>::apply(*this, sep, end, view, fp);
 	}
 
-	TableInfo< Types... >* rename(const char* name) {
+	TableInfo<Types...>* rename(const char* name) {
 		this->name = name;
 		return this;
 	}
+	template <size_t ...Is> 
+	void inline
+	reserve(std::index_sequence<Is...>, uint32_t size) {
+		const auto& assign_sz = [&size](auto& col){ col.size = size;};
+		(assign_sz(get_col<Is>(*this)), ...);
+	}
+	template <size_t ...Is> 
+	decltype(auto) inline 
+	get_record(std::index_sequence<Is...>, uint32_t i) {
+		return std::forward_as_tuple((get_col<Is>(*this)[i], ...));
+	}
+	template <size_t ...Is> 
+	void inline 
+	set_record(std::index_sequence<Is...>, tuple_type t) {
+		const auto& assign_field = 
+			[](auto& l, const auto& r){
+				l = r;
+			};
+		(assign_field(get_col<Is>(*this)[Is], std::get<Is>(t)), ...);
+	}
+	TableInfo<Types ...>* distinct() {
+		std::unordered_set<tuple_type> d_records;
+		std::make_index_sequence<sizeof...(Types)> seq;
+		
+		for (uint32_t j = 0; j < colrefs[0].size; ++j) {
+			d_records.insert(get_record(seq, j));
+		}
+		reserve(seq, d_records.size());
+		for (const auto& dr : d_records) {
+			set_record(seq, dr);
+		}
+		return this;
+	}
 	// defined in monetdb_conn.cpp
 	void monetdb_append_table(void* srv, const char* alt_name = nullptr);
 };
@@ -419,6 +468,7 @@ struct TableInfo {
 
 template<class ...Types>
 struct TableView {
+	typedef std::tuple<Types...> tuple_type;
 	const vector_type<uint32_t>* idxs;
 	const TableInfo<Types...>& info;
 	constexpr TableView(const vector_type<uint32_t>* idxs, const TableInfo<Types...>& info) noexcept : idxs(idxs), info(info) {}
diff --git a/server/vector_type.hpp b/server/vector_type.hpp
index c56d7c2..720db75 100644
--- a/server/vector_type.hpp
+++ b/server/vector_type.hpp
@@ -11,6 +11,8 @@
 #include <cstdint>
 #include <iterator>
 #include <initializer_list>
+#include <unordered_set>
+#include "hasher.h"
 #include "types.h"
 
 #pragma pack(push, 1)
@@ -107,6 +109,34 @@ public:
 		
 		return *this;
 	}
+	inline std::unordered_set<value_t> distinct_common(){
+		return std::unordered_set<value_t>(container, container + size);
+	}
+	vector_type<_Ty>& distinct_inplace(){
+		uint32_t i = 0;
+		for(const auto& v : distinct_common()){
+			container[i++] = v;
+		}
+		return *this;
+	}
+	vector_type<_Ty> distinct_copy(){
+		auto d_vals = distinct_common();
+		vector_type<_Ty> ret(d_vals.size());
+		uint32_t i = 0;
+		for(const auto& v : d_vals){
+			ret[i++] = v;
+		}
+		return ret;
+	}
+	uint32_t distinct_size(){
+		return distinct_common().size();
+	}
+	vector_type<_Ty> distinct(){
+		if (capacity)
+			return distinct_inplace();
+		else
+			return distinct_copy();
+	}
 	inline void grow() {
 		if (size >= capacity) { // geometric growth
 			uint32_t new_capacity = size + 1 + (size >> 1);