enable nullable for Decimal [CLICKHOUSE-3765]

dbms/src/Columns/ColumnDecimal.h

@@ -77,7 +77,7 @@ public:
     const char * getFamilyName() const override { return TypeName<T>::get(); }
 
     bool isNumeric() const override { return false; }
-    bool canBeInsideNullable() const override { return false; }
+    bool canBeInsideNullable() const override { return true; }
     bool isFixedAndContiguous() const override { return true; }
     size_t sizeOfValueIfFixed() const override { return sizeof(T); }
 

dbms/src/DataTypes/DataTypesDecimal.h

@@ -148,7 +148,7 @@ public:
     bool canBeUsedInBooleanContext() const override { return true; }
     bool isNumber() const override { return true; }
     bool isInteger() const override { return false; }
-    bool canBeInsideNullable() const override { return false; }
+    bool canBeInsideNullable() const override { return true; }
 
     /// Decimal specific
 

dbms/tests/queries/0_stateless/00700_decimal_casts.sql

@@ -1,14 +1,6 @@
 SET allow_experimental_decimal_type = 1;
 SET send_logs_level = 'none';
 
-CREATE TABLE IF NOT EXISTS test.x (a Nullable(Decimal(9, 2))) ENGINE = Memory; -- { serverError 43 }
-CREATE TABLE IF NOT EXISTS test.x (a Nullable(Decimal(18, 2))) ENGINE = Memory; -- { serverError 43 }
-CREATE TABLE IF NOT EXISTS test.x (a Nullable(Decimal(38, 2))) ENGINE = Memory; -- { serverError 43 }
-
-SELECT toNullable(toDecimal32(0, 0)); -- { serverError 43 }
-SELECT toNullable(toDecimal64(0, 0)); -- { serverError 43 }
-SELECT toNullable(toDecimal128(0, 0)); -- { serverError 43 }
-
 SELECT toDecimal32('1.1', 1), toDecimal32('1.1', 2), toDecimal32('1.1', 8);
 SELECT toDecimal32('1.1', 0); -- { serverError 69 }
 SELECT toDecimal32(1.1, 0), toDecimal32(1.1, 1), toDecimal32(1.1, 2), toDecimal32(1.1, 8);

dbms/tests/queries/0_stateless/00700_decimal_null.reference

@@ -0,0 +1,39 @@
+32	32
+64	64
+128	128
+1	1	1
+2	2	2
+3	3	3
+4	4	4
+5	5	5
+6	6	6
+7	7	7
+8	8	8
+\N	\N
+\N	\N
+1	1
+1	1
+\N
+\N
+1
+1
+1.10	1.10000	1.10000	1.1000	1.10000000	1.10000000
+2.20	2.20000	2.20000	2.2000	\N	\N
+3.30	3.30000	3.30000	\N	3.30000000	\N
+4.40	4.40000	4.40000	\N	\N	4.40000000
+5.50	5.50000	5.50000	\N	\N	\N
+0	1
+0	1
+0	1
+1	0
+1	0
+1	0
+5
+5
+5
+3
+3
+3
+2
+2
+2

dbms/tests/queries/0_stateless/00700_decimal_null.sql

@@ -0,0 +1,65 @@
+SET send_logs_level = 'none';
+SET allow_experimental_decimal_type = 1;
+
+CREATE DATABASE IF NOT EXISTS test;
+DROP TABLE IF EXISTS test.decimal;
+
+CREATE TABLE IF NOT EXISTS test.decimal
+(
+    a DEC(9, 2),
+    b DEC(18, 5),
+    c DEC(38, 5),
+    d Nullable(DEC(9, 4)),
+    e Nullable(DEC(18, 8)),
+    f Nullable(DEC(38, 8))
+) ENGINE = Memory;
+
+SELECT toNullable(toDecimal32(32, 0)) AS x, assumeNotNull(x);
+SELECT toNullable(toDecimal64(64, 0)) AS x, assumeNotNull(x);
+SELECT toNullable(toDecimal128(128, 0)) AS x, assumeNotNull(x);
+SELECT NULL AS x, assumeNotNull(x); -- { serverError 48 }
+
+SELECT ifNull(toDecimal32(1, 0), NULL), ifNull(toDecimal64(1, 0), NULL), ifNull(toDecimal128(1, 0), NULL);
+SELECT ifNull(toNullable(toDecimal32(2, 0)), NULL), ifNull(toNullable(toDecimal64(2, 0)), NULL), ifNull(toNullable(toDecimal128(2, 0)), NULL);
+SELECT ifNull(NULL, toDecimal32(3, 0)), ifNull(NULL, toDecimal64(3, 0)), ifNull(NULL, toDecimal128(3, 0));
+SELECT ifNull(NULL, toNullable(toDecimal32(4, 0))), ifNull(NULL, toNullable(toDecimal64(4, 0))), ifNull(NULL, toNullable(toDecimal128(4, 0)));
+
+SELECT coalesce(toDecimal32(5, 0), NULL), coalesce(toDecimal64(5, 0), NULL), coalesce(toDecimal128(5, 0), NULL);
+SELECT coalesce(NULL, toDecimal32(6, 0)), coalesce(NULL, toDecimal64(6, 0)), coalesce(NULL, toDecimal128(6, 0));
+
+SELECT coalesce(toNullable(toDecimal32(7, 0)), NULL), coalesce(toNullable(toDecimal64(7, 0)), NULL), coalesce(toNullable(toDecimal128(7, 0)), NULL);
+SELECT coalesce(NULL, toNullable(toDecimal32(8, 0))), coalesce(NULL, toNullable(toDecimal64(8, 0))), coalesce(NULL, toNullable(toDecimal128(8, 0)));
+
+SELECT nullIf(toNullable(toDecimal32(1, 0)), toDecimal32(1, 0)), nullIf(toNullable(toDecimal64(1, 0)), toDecimal64(1, 0));
+SELECT nullIf(toDecimal32(1, 0), toNullable(toDecimal32(1, 0))), nullIf(toDecimal64(1, 0), toNullable(toDecimal64(1, 0)));
+SELECT nullIf(toNullable(toDecimal32(1, 0)), toDecimal32(2, 0)), nullIf(toNullable(toDecimal64(1, 0)), toDecimal64(2, 0));
+SELECT nullIf(toDecimal32(1, 0), toNullable(toDecimal32(2, 0))), nullIf(toDecimal64(1, 0), toNullable(toDecimal64(2, 0)));
+SELECT nullIf(toNullable(toDecimal128(1, 0)), toDecimal128(1, 0));
+SELECT nullIf(toDecimal128(1, 0), toNullable(toDecimal128(1, 0)));
+SELECT nullIf(toNullable(toDecimal128(1, 0)), toDecimal128(2, 0));
+SELECT nullIf(toDecimal128(1, 0), toNullable(toDecimal128(2, 0)));
+
+INSERT INTO test.decimal (a, b, c, d, e, f) VALUES (1.1, 1.1, 1.1, 1.1, 1.1, 1.1);
+INSERT INTO test.decimal (a, b, c, d) VALUES (2.2, 2.2, 2.2, 2.2);
+INSERT INTO test.decimal (a, b, c, e) VALUES (3.3, 3.3, 3.3, 3.3);
+INSERT INTO test.decimal (a, b, c, f) VALUES (4.4, 4.4, 4.4, 4.4);
+INSERT INTO test.decimal (a, b, c) VALUES (5.5, 5.5, 5.5);
+
+SELECT * FROM test.decimal ORDER BY d, e, f;
+SELECT isNull(a), isNotNull(a) FROM test.decimal WHERE a = toDecimal32(5.5, 1);
+SELECT isNull(b), isNotNull(b) FROM test.decimal WHERE a = toDecimal32(5.5, 1);
+SELECT isNull(c), isNotNull(c) FROM test.decimal WHERE a = toDecimal32(5.5, 1);
+SELECT isNull(d), isNotNull(d) FROM test.decimal WHERE a = toDecimal32(5.5, 1);
+SELECT isNull(e), isNotNull(e) FROM test.decimal WHERE a = toDecimal32(5.5, 1);
+SELECT isNull(f), isNotNull(f) FROM test.decimal WHERE a = toDecimal32(5.5, 1);
+SELECT count() FROM test.decimal WHERE a IS NOT NULL;
+SELECT count() FROM test.decimal WHERE b IS NOT NULL;
+SELECT count() FROM test.decimal WHERE c IS NOT NULL;
+SELECT count() FROM test.decimal WHERE d IS NULL;
+SELECT count() FROM test.decimal WHERE e IS NULL;
+SELECT count() FROM test.decimal WHERE f IS NULL;
+SELECT count() FROM test.decimal WHERE d IS NULL AND e IS NULL;
+SELECT count() FROM test.decimal WHERE d IS NULL AND f IS NULL;
+SELECT count() FROM test.decimal WHERE e IS NULL AND f IS NULL;
+
+DROP TABLE IF EXISTS test.decimal;