feat: add type extension for column (#122)

* feat: decimal128 proto

* chore: make all

* chore: empty line

* refactor: remove precision and scale

* chore: cr comment

Co-authored-by: Yingwen <realevenyag@gmail.com>

---------

Co-authored-by: Yingwen <realevenyag@gmail.com>

proto/greptime/v1/column.proto

@@ -61,6 +61,7 @@ message Column {
     repeated int64 duration_millisecond_values = 28;
     repeated int64 duration_microsecond_values = 29;
     repeated int64 duration_nanosecond_values = 30;
+    repeated Decimal128 decimal128_values = 31;
   }
   // The array of non-null values in this column.
   //
@@ -80,4 +81,7 @@ message Column {
 
   // Helpful in creating vector from column.
   ColumnDataType datatype = 5;
+
+  // Extension for ColumnDataType.
+  ColumnDataTypeExtension datatype_extension = 6;
 }

proto/greptime/v1/common.proto

@@ -97,6 +97,7 @@ enum ColumnDataType {
   DURATION_MILLISECOND = 27;
   DURATION_MICROSECOND = 28;
   DURATION_NANOSECOND = 29;
+  DECIMAL128 = 30;
 }
 
 message IntervalMonthDayNano {
@@ -104,3 +105,21 @@ message IntervalMonthDayNano {
   int32 days = 2;
   int64 nanoseconds = 3;
 }
+
+// (hi: high 64 bits, lo: low 64 bits) are used to keep the decimal128 value.
+message Decimal128 {
+  int64 hi = 1;
+  int64 lo = 2;
+}
+
+// Type extension for some complex types
+message ColumnDataTypeExtension {
+  oneof type_ext {
+    DecimalTypeExtension decimal_type = 1;
+  }
+}
+
+message DecimalTypeExtension {
+  int32 precision = 1;
+  int32 scale = 2;
+}

proto/greptime/v1/ddl.proto

@@ -103,6 +103,8 @@ message ColumnDef {
   bytes default_constraint = 4;
   SemanticType semantic_type = 5;
   string comment = 6;
+  // Extension for ColumnDataType.
+  ColumnDataTypeExtension datatype_extension = 7;
 }
 
 message AddColumnLocation {

proto/greptime/v1/row.proto

@@ -31,6 +31,8 @@ message ColumnSchema {
   string column_name = 1;
   ColumnDataType datatype = 2;
   SemanticType semantic_type = 3;
+  // Extension for ColumnDataType.
+  ColumnDataTypeExtension datatype_extension = 4;
 }
 
 message Row { repeated Value values = 1; }
@@ -71,5 +73,6 @@ message Value {
     int64 duration_millisecond_value = 28;
     int64 duration_microsecond_value = 29;
     int64 duration_nanosecond_value = 30;
+    Decimal128 decimal128_value = 31;
   }
 }