From 3e89fb8414b8811445806424b8644418a329e5c3 Mon Sep 17 00:00:00 2001
From: Brendan Younger <github@brendanyounger.com>
Date: Tue, 25 Apr 2023 10:37:22 -0400
Subject: [PATCH] Add support for decimal types

---
 src/common.cpp | 15 +++++++++++++++
 src/reader.cpp | 16 ++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/src/common.cpp b/src/common.cpp
index 5439098..3bdbda6 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -10,6 +10,7 @@ extern "C"
 #include "utils/memutils.h"
 #include "utils/memdebug.h"
 #include "utils/timestamp.h"
+#include "utils/numeric.h"
 }
 
 #if PG_VERSION_NUM < 130000
@@ -69,6 +70,8 @@ to_postgres_type(int arrow_type)
             return TIMESTAMPOID;
         case arrow::Type::DATE32:
             return DATEOID;
+        case arrow::Type::DECIMAL:
+            return NUMERICOID;
         default:
             return InvalidOid;
     }
@@ -114,6 +117,18 @@ bytes_to_postgres_type(const char *bytes, Size len, const arrow::DataType *arrow
         case arrow::Type::DATE32:
             return DateADTGetDatum(*(int32 *) bytes +
                                    (UNIX_EPOCH_JDATE - POSTGRES_EPOCH_JDATE));
+        case arrow::Type::DECIMAL128: {
+            auto dectype = (arrow::Decimal128Type *)arrow_type;
+            std::string val = arrow::Decimal128(bytes).ToString(dectype->scale());
+
+            return NumericGetDatum(DirectFunctionCall1(numeric_in, CStringGetDatum(val.c_str())));
+        }
+        case arrow::Type::DECIMAL256: {
+            auto dectype = (arrow::Decimal256Type *)arrow_type;
+            std::string val = arrow::Decimal256(bytes).ToString(dectype->scale());
+
+            return NumericGetDatum(DirectFunctionCall1(numeric_in, CStringGetDatum(val.c_str())));
+        }
         default:
             return PointerGetDatum(NULL);
     }
diff --git a/src/reader.cpp b/src/reader.cpp
index f276d4b..1be2ac9 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -466,6 +466,22 @@ Datum ParquetReader::read_primitive_type(arrow::Array *array,
             res = DateADTGetDatum(d + (UNIX_EPOCH_JDATE - POSTGRES_EPOCH_JDATE));
             break;
         }
+        case arrow::Type::DECIMAL128:
+        {
+            arrow::Decimal128Array *decarray = (arrow::Decimal128Array *) array;
+            std::string val = decarray->FormatValue(i);
+
+            res = NumericGetDatum(DirectFunctionCall1(numeric_in, CStringGetDatum(val.c_str())));
+            break;
+        }
+        case arrow::Type::DECIMAL256:
+        {
+            arrow::Decimal256Array *decarray = (arrow::Decimal256Array *) array;
+            std::string val = decarray->FormatValue(i);
+
+            res = NumericGetDatum(DirectFunctionCall1(numeric_in, CStringGetDatum(val.c_str())));
+            break;
+        }
         /* TODO: add other types */
         default:
             throw Error("parquet_fdw: unsupported column type: %s",