Add support for the Decimal data type

Makefile

@@ -32,9 +32,9 @@ CH_CPP_FLAGS = -D CMAKE_BUILD_TYPE=Release -D WITH_OPENSSL=ON
 
 # Build static on Darwin by default.
 ifndef ($(CH_BUILD))
-ifeq ($(OS),Darwin)
+# ifeq ($(OS),Darwin)
 	CH_BUILD = static
-endif
+# endif
 endif
 
 # Are we statically compiling clickhouse-cpp into the extension or no?

src/binary.cpp

@@ -1,3 +1,4 @@
+#include <sstream>
 #include <iostream>
 #include <cassert>
 #include <stdexcept>
@@ -250,6 +251,11 @@ static Oid get_corr_postgres_type(const TypeRef & type)
 			return FLOAT4OID;
 		case Type::Code::Float64:
 			return FLOAT8OID;
+		case Type::Code::Decimal128:
+		case Type::Code::Decimal64:
+		case Type::Code::Decimal32:
+		case Type::Code::Decimal:
+			return NUMERICOID;
 		case Type::Code::FixedString:
 		case Type::Code::Enum8:
 		case Type::Code::Enum16:
@@ -461,6 +467,26 @@ static void column_append(clickhouse::ColumnRef col, Datum val, Oid valtype, boo
 			}
 			break;
 		}
+		case NUMERICOID: {
+			// Convert numeric to string and let ColumnDecimal parse it.
+			char *s = DatumGetCString(DirectFunctionCall1(numeric_out, val));
+			switch (col->Type()->GetCode())
+			{
+				case Type::Code::Decimal128:
+				case Type::Code::Decimal64:
+				case Type::Code::Decimal32:
+				case Type::Code::Decimal:
+					col->As<ColumnDecimal>()->Append(std::string(s));
+					break;
+				default:
+					throw std::runtime_error(
+						"unexpected column "
+						"type for NUMERIC: "
+						+ col->Type()->GetName());
+			}
+			pfree(s);
+			break;
+		}
 		case TEXTOID: {
 			char * s = TextDatumGetCString(val);
 
@@ -745,6 +771,55 @@ static Datum make_datum(clickhouse::ColumnRef col, size_t row, Oid * valtype, bo
 			*valtype = FLOAT8OID;
 		}
 		break;
+		case Type::Code::Decimal128:
+		case Type::Code::Decimal64:
+		case Type::Code::Decimal32:
+		case Type::Code::Decimal:
+		{
+			auto decCol = col->As<ColumnDecimal>();
+			auto val = decCol->At(row);
+
+			// Convert the Int128 to a string.
+			std::stringstream ss;
+			ss << val;
+			std::string str = ss.str();
+
+			// Start a destination string.
+			std::stringstream res;
+			auto scale = decCol->GetScale();
+
+			// Output a dash for negative values
+			if (val < 0)
+			{
+				res << '-';
+				str.erase(0, 1);
+			}
+
+			if (str.length() <= scale)
+			{
+				// Append the entire value prepended with zeros after the decimal.
+				res << "0." << std::string(scale-1, '0') << str;
+			}
+			else
+			{
+				// There are digits before the decimal.
+				auto decAt = str.length() - scale;
+				res << str.substr(0, decAt);
+
+				// Append any digits after the decimal.
+				if (decAt < str.length())
+				{
+					res << '.' << str.substr(decAt);
+				}
+			}
+
+			ret = DirectFunctionCall3(numeric_in,
+										CStringGetDatum(res.str().c_str()),
+										ObjectIdGetDatum(0),
+										Int32GetDatum(-1));
+			*valtype = NUMERICOID;
+		}
+		break;
 		case Type::Code::FixedString: {
 			auto s = std::string(col->As<ColumnFixedString>()->At(row));
 			ret = CStringGetTextDatum(s.c_str());

src/pglink.c

@@ -377,12 +377,9 @@ extend_insert_query(ch_http_insert_state *state, TupleTableSlot *slot)
 			break;
 			case NUMERICOID:
 			{
-				Datum  valueDatum;
-				float8 f;
-
-				valueDatum = DirectFunctionCall1(numeric_float8, value);
-				f = DatumGetFloat8(valueDatum);
-				appendStringInfo(&state->sql, "%f", f);
+				char *extval = DatumGetCString(DirectFunctionCall1(numeric_out, value));
+				appendStringInfoString(&state->sql, extval);
+				pfree(extval);
 			}
 			break;
 			case BPCHAROID:

test/expected/decimal.out

@@ -0,0 +1,104 @@
+SET datestyle = 'ISO';
+CREATE SERVER binary_decimal_loopback FOREIGN DATA WRAPPER clickhouse_fdw OPTIONS(dbname 'decimal_test', driver 'binary');
+CREATE SERVER http_decimal_loopback FOREIGN DATA WRAPPER clickhouse_fdw OPTIONS(dbname 'decimal_test', driver 'http');
+CREATE USER MAPPING FOR CURRENT_USER SERVER binary_decimal_loopback;
+CREATE USER MAPPING FOR CURRENT_USER SERVER http_decimal_loopback;
+SELECT clickhouse_raw_query('DROP DATABASE IF EXISTS decimal_test');
+ clickhouse_raw_query 
+----------------------
+
+(1 row)
+
+SELECT clickhouse_raw_query('CREATE DATABASE decimal_test');
+ clickhouse_raw_query 
+----------------------
+
+(1 row)
+
+SELECT clickhouse_raw_query($$
+    CREATE TABLE decimal_test.decimals (
+        id     Int32          NOT NULL,
+        dec    Decimal(8, 0)  NOT NULL,
+        dec32  Decimal32(4)   NOT NULL,
+        dec64  Decimal64(6)   NOT NULL,
+        dec128 Decimal128(8)  NOT NULL
+    ) ENGINE = MergeTree PARTITION BY id ORDER BY (id);
+$$);
+ clickhouse_raw_query 
+----------------------
+
+(1 row)
+
+CREATE SCHEMA dec_bin;
+CREATE SCHEMA dec_http;
+IMPORT FOREIGN SCHEMA "decimal_test" FROM SERVER binary_decimal_loopback INTO dec_bin;
+\d dec_bin.decimals
+                   Foreign table "dec_bin.decimals"
+ Column |     Type      | Collation | Nullable | Default | FDW options 
+--------+---------------+-----------+----------+---------+-------------
+ id     | integer       |           | not null |         | 
+ dec    | numeric(8,0)  |           | not null |         | 
+ dec32  | numeric(9,4)  |           | not null |         | 
+ dec64  | numeric(18,6) |           | not null |         | 
+ dec128 | numeric(38,8) |           | not null |         | 
+Server: binary_decimal_loopback
+FDW options: (database 'decimal_test', table_name 'decimals', engine 'MergeTree')
+
+IMPORT FOREIGN SCHEMA "decimal_test" FROM SERVER http_decimal_loopback INTO dec_http;
+\d dec_http.decimals
+                   Foreign table "dec_http.decimals"
+ Column |     Type      | Collation | Nullable | Default | FDW options 
+--------+---------------+-----------+----------+---------+-------------
+ id     | integer       |           | not null |         | 
+ dec    | numeric(8,0)  |           | not null |         | 
+ dec32  | numeric(9,4)  |           | not null |         | 
+ dec64  | numeric(18,6) |           | not null |         | 
+ dec128 | numeric(38,8) |           | not null |         | 
+Server: http_decimal_loopback
+FDW options: (database 'decimal_test', table_name 'decimals', engine 'MergeTree')
+
+-- Fails pending https://github.com/ClickHouse/clickhouse-cpp/issues/422
+INSERT INTO dec_bin.decimals (id, dec, dec32, dec64, dec128) VALUES
+    (1, 42::NUMERIC, 98.6::NUMERIC, 102.4::NUMERIC, 1024.003::NUMERIC),
+    (2, 9999, 9999.9999, 9999999.999999, 99999999999.99999999),
+    (3, -9999, -9999.9999, -9999999.999999, -99999999999.99999999)
+;
+INSERT INTO dec_http.decimals VALUES
+    (4, 1000000::NUMERIC, 10000::NUMERIC, 3000000000::NUMERIC, 400000000000::NUMERIC),
+    (5, -1, -0.0001, -0.000001, -0.00000001),
+    (6, 0, 0, 0, 0)
+;
+SELECT * FROM dec_bin.decimals ORDER BY id;
+ id |   dec   |   dec32    |       dec64       |        dec128         
+----+---------+------------+-------------------+-----------------------
+  1 |      42 |    98.6000 |        102.400000 |         1024.00300000
+  2 |    9999 |  9999.9999 |    9999999.999999 |  99999999999.99999999
+  3 |   -9999 | -9999.9999 |   -9999999.999999 | -99999999999.99999999
+  4 | 1000000 | 10000.0000 | 3000000000.000000 | 400000000000.00000000
+  5 |      -1 |    -0.0001 |         -0.000001 |           -0.00000001
+  6 |       0 |     0.0000 |          0.000000 |            0.00000000
+(6 rows)
+
+SELECT * FROM dec_http.decimals ORDER BY id;
+ id |   dec   |   dec32    |       dec64       |        dec128         
+----+---------+------------+-------------------+-----------------------
+  1 |      42 |    98.6000 |        102.400000 |         1024.00300000
+  2 |    9999 |  9999.9999 |    9999999.999999 |  99999999999.99999999
+  3 |   -9999 | -9999.9999 |   -9999999.999999 | -99999999999.99999999
+  4 | 1000000 | 10000.0000 | 3000000000.000000 | 400000000000.00000000
+  5 |      -1 |    -0.0001 |         -0.000001 |           -0.00000001
+  6 |       0 |     0.0000 |          0.000000 |            0.00000000
+(6 rows)
+
+SELECT clickhouse_raw_query('DROP DATABASE decimal_test');
+ clickhouse_raw_query 
+----------------------
+
+(1 row)
+
+DROP USER MAPPING FOR CURRENT_USER SERVER binary_decimal_loopback;
+DROP USER MAPPING FOR CURRENT_USER SERVER http_decimal_loopback;
+DROP SERVER binary_decimal_loopback CASCADE;
+NOTICE:  drop cascades to foreign table dec_bin.decimals
+DROP SERVER http_decimal_loopback CASCADE;
+NOTICE:  drop cascades to foreign table dec_http.decimals

test/sql/decimal.sql

@@ -0,0 +1,46 @@
+SET datestyle = 'ISO';
+CREATE SERVER binary_decimal_loopback FOREIGN DATA WRAPPER clickhouse_fdw OPTIONS(dbname 'decimal_test', driver 'binary');
+CREATE SERVER http_decimal_loopback FOREIGN DATA WRAPPER clickhouse_fdw OPTIONS(dbname 'decimal_test', driver 'http');
+CREATE USER MAPPING FOR CURRENT_USER SERVER binary_decimal_loopback;
+CREATE USER MAPPING FOR CURRENT_USER SERVER http_decimal_loopback;
+
+SELECT clickhouse_raw_query('DROP DATABASE IF EXISTS decimal_test');
+SELECT clickhouse_raw_query('CREATE DATABASE decimal_test');
+SELECT clickhouse_raw_query($$
+    CREATE TABLE decimal_test.decimals (
+        id     Int32          NOT NULL,
+        dec    Decimal(8, 0)  NOT NULL,
+        dec32  Decimal32(4)   NOT NULL,
+        dec64  Decimal64(6)   NOT NULL,
+        dec128 Decimal128(8)  NOT NULL
+    ) ENGINE = MergeTree PARTITION BY id ORDER BY (id);
+$$);
+
+CREATE SCHEMA dec_bin;
+CREATE SCHEMA dec_http;
+IMPORT FOREIGN SCHEMA "decimal_test" FROM SERVER binary_decimal_loopback INTO dec_bin;
+\d dec_bin.decimals
+IMPORT FOREIGN SCHEMA "decimal_test" FROM SERVER http_decimal_loopback INTO dec_http;
+\d dec_http.decimals
+
+-- Fails pending https://github.com/ClickHouse/clickhouse-cpp/issues/422
+INSERT INTO dec_bin.decimals (id, dec, dec32, dec64, dec128) VALUES
+    (1, 42::NUMERIC, 98.6::NUMERIC, 102.4::NUMERIC, 1024.003::NUMERIC),
+    (2, 9999, 9999.9999, 9999999.999999, 99999999999.99999999),
+    (3, -9999, -9999.9999, -9999999.999999, -99999999999.99999999)
+;
+
+INSERT INTO dec_http.decimals VALUES
+    (4, 1000000::NUMERIC, 10000::NUMERIC, 3000000000::NUMERIC, 400000000000::NUMERIC),
+    (5, -1, -0.0001, -0.000001, -0.00000001),
+    (6, 0, 0, 0, 0)
+;
+
+SELECT * FROM dec_bin.decimals ORDER BY id;
+SELECT * FROM dec_http.decimals ORDER BY id;
+
+SELECT clickhouse_raw_query('DROP DATABASE decimal_test');
+DROP USER MAPPING FOR CURRENT_USER SERVER binary_decimal_loopback;
+DROP USER MAPPING FOR CURRENT_USER SERVER http_decimal_loopback;
+DROP SERVER binary_decimal_loopback CASCADE;
+DROP SERVER http_decimal_loopback CASCADE;