Support type="double" for columns,

It already supports `real`, which is single precision floating point in
PostgreSQL. This patch adds `type = "double"` for PostgreSQL `double
precision` columns

Author: amandasaurus

src/flex-table-column.cpp

@@ -45,6 +45,7 @@ std::vector<column_type_lookup> const COLUMN_TYPES = {
      {"int8", table_column_type::int8},
      {"bigint", table_column_type::int8},
      {"real", table_column_type::real},
+     {"double", table_column_type::double_},
      {"timestamp", table_column_type::timestamp},
      {"timestamptz", table_column_type::timestamptz},
      {"hstore", table_column_type::hstore},
@@ -146,6 +147,8 @@ std::string flex_table_column_t::sql_type_name() const
         return "int8";
     case table_column_type::real:
         return "real";
+    case table_column_type::double_:
+        return "double precision";
     case table_column_type::timestamp:
         return "timestamp";
     case table_column_type::timestamptz:

src/flex-table-column.hpp

@@ -32,6 +32,7 @@ enum class table_column_type : uint8_t
     int8,
 
     real,
+    double_,
 
     timestamp,
     timestamptz,

src/flex-write.cpp

@@ -359,6 +359,16 @@ void flex_write_column(lua_State *lua_state, geometry_cache_t *geom_cache,
             throw fmt_error("Invalid type '{}' for real column.",
                             lua_typename(lua_state, ltype));
         }
+    } else if (column.type() == table_column_type::double_) {
+        if (ltype == LUA_TNUMBER) {
+            copy_mgr->add_column(lua_tonumber(lua_state, -1));
+        } else if (ltype == LUA_TSTRING) {
+            write_double(copy_mgr, column,
+                         lua_tolstring(lua_state, -1, nullptr));
+        } else {
+            throw fmt_error("Invalid type '{}' for double column.",
+                            lua_typename(lua_state, ltype));
+        }
     } else if (column.type() == table_column_type::timestamp) {
         if (ltype == LUA_TNUMBER) {
             auto const ts = osmium::Timestamp{lua_tointeger(lua_state, -1)};