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MDEV-36851: COALESCE() returns nullable column while IFNULL() does not

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Nullability is decided in two stages-

1. Based on argument NULL-ness

Problem:
- COALESCE currently uses a generic logic- "Result of a function
  is nullable if any of the arguments is nullable", which is wrong.
- IFNULL sets nullability using second argument alone, which incorrectly
  sets the result to NULL even when first argument is not null.

Fix:
- Result of COALESCE and IFNULL is set to NULL only if all arguments are
  NULL.

2. Based on type conversion safety of fallback value

Problem:
- The generic `Item_hybrid_func_fix_attributes` logic would mark the
  function's result as nullable if any argument involved a type
  conversion that could yield NULL.

Fix:
- For COALESCE and IFNULL, nullability is set to NOT NULL if the first
  non-null argument can be safely converted to function's target return
  type.
- For other functions, if any argument's conversion to target type could
  result in NULL, the function is marked nullable.

Tests included in `mysql-test/main/func_hybrid_type.test`
This commit is contained in:
raghunandanbhat 2025-05-30 17:44:55 +05:30 committed by Raghunandan Bhat
parent c427618462
commit bff9b1e472
20 changed files with 345 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
mysql-test/main/case.result
View File

@ -165,7 +165,7 @@ t1 CREATE TABLE `t1` (
`COALESCE(1,1.0)` decimal(2,1) NOT NULL,
`COALESCE(1,'1')` varchar(1) NOT NULL,
`COALESCE(1.1,'1')` varchar(4) NOT NULL,
`COALESCE('a' COLLATE latin1_bin,'b')` varchar(1) CHARACTER SET latin1 COLLATE latin1_bin DEFAULT NULL
`COALESCE('a' COLLATE latin1_bin,'b')` varchar(1) CHARACTER SET latin1 COLLATE latin1_bin NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t1;
CREATE TABLE t1 SELECT IFNULL('a' COLLATE latin1_swedish_ci, 'b' COLLATE latin1_bin);

4
mysql-test/main/ctype_binary.result
View File

@ -2621,7 +2621,7 @@ GROUP_CONCAT(CASE WHEN a THEN a ELSE '' END)
1234567
SELECT COALESCE(a,'') FROM t1 GROUP BY 1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def COALESCE(a,'') 253 9 7 Y 128 39 63
def COALESCE(a,'') 253 9 7 N 129 39 63
COALESCE(a,'')
1234567
# All columns must be VARCHAR(9) with the same length:
@ -2640,7 +2640,7 @@ t2 CREATE TABLE `t2` (
`IFNULL(a,'')` varbinary(9) NOT NULL,
`IF(a,a,'')` varbinary(9) DEFAULT NULL,
`CASE WHEN a THEN a ELSE '' END` varbinary(9) DEFAULT NULL,
`COALESCE(a,'')` varbinary(9) DEFAULT NULL
`COALESCE(a,'')` varbinary(9) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT CONCAT_WS(1,2,3) FROM t1;

4
mysql-test/main/ctype_cp1251.result
View File

@ -3033,7 +3033,7 @@ GROUP_CONCAT(CASE WHEN a THEN a ELSE '' END)
1234567
SELECT COALESCE(a,'') FROM t1 GROUP BY 1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def COALESCE(a,'') 253 9 7 Y 0 39 51
def COALESCE(a,'') 253 9 7 N 1 39 51
COALESCE(a,'')
1234567
# All columns must be VARCHAR(9) with the same length:
@ -3052,7 +3052,7 @@ t2 CREATE TABLE `t2` (
`IFNULL(a,'')` varchar(9) CHARACTER SET cp1251 COLLATE cp1251_general_ci NOT NULL,
`IF(a,a,'')` varchar(9) CHARACTER SET cp1251 COLLATE cp1251_general_ci DEFAULT NULL,
`CASE WHEN a THEN a ELSE '' END` varchar(9) CHARACTER SET cp1251 COLLATE cp1251_general_ci DEFAULT NULL,
`COALESCE(a,'')` varchar(9) CHARACTER SET cp1251 COLLATE cp1251_general_ci DEFAULT NULL
`COALESCE(a,'')` varchar(9) CHARACTER SET cp1251 COLLATE cp1251_general_ci NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT CONCAT_WS(1,2,3) FROM t1;

4
mysql-test/main/ctype_latin1.result
View File

@ -3342,7 +3342,7 @@ GROUP_CONCAT(CASE WHEN a THEN a ELSE '' END)
1234567
SELECT COALESCE(a,'') FROM t1 GROUP BY 1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def COALESCE(a,'') 253 9 7 Y 0 39 8
def COALESCE(a,'') 253 9 7 N 1 39 8
COALESCE(a,'')
1234567
# All columns must be VARCHAR(9) with the same length:
@ -3361,7 +3361,7 @@ t2 CREATE TABLE `t2` (
`IFNULL(a,'')` varchar(9) NOT NULL,
`IF(a,a,'')` varchar(9) DEFAULT NULL,
`CASE WHEN a THEN a ELSE '' END` varchar(9) DEFAULT NULL,
`COALESCE(a,'')` varchar(9) DEFAULT NULL
`COALESCE(a,'')` varchar(9) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT CONCAT_WS(1,2,3) FROM t1;

4
mysql-test/main/ctype_ucs.result
View File

@ -4226,7 +4226,7 @@ GROUP_CONCAT(CASE WHEN a THEN a ELSE '' END)
1234567
SELECT COALESCE(a,'') FROM t1 GROUP BY 1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def COALESCE(a,'') 253 9 7 Y 0 39 8
def COALESCE(a,'') 253 9 7 N 1 39 8
COALESCE(a,'')
1234567
# All columns must be VARCHAR(9) with the same length:
@ -4245,7 +4245,7 @@ t2 CREATE TABLE `t2` (
`IFNULL(a,'')` varchar(9) CHARACTER SET ucs2 COLLATE ucs2_general_ci NOT NULL,
`IF(a,a,'')` varchar(9) CHARACTER SET ucs2 COLLATE ucs2_general_ci DEFAULT NULL,
`CASE WHEN a THEN a ELSE '' END` varchar(9) CHARACTER SET ucs2 COLLATE ucs2_general_ci DEFAULT NULL,
`COALESCE(a,'')` varchar(9) CHARACTER SET ucs2 COLLATE ucs2_general_ci DEFAULT NULL
`COALESCE(a,'')` varchar(9) CHARACTER SET ucs2 COLLATE ucs2_general_ci NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT CONCAT_WS(1,2,3) FROM t1;

4
mysql-test/main/ctype_utf8.result
View File

@ -5093,7 +5093,7 @@ GROUP_CONCAT(CASE WHEN a THEN a ELSE '' END)
1234567
SELECT COALESCE(a,'') FROM t1 GROUP BY 1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def COALESCE(a,'') 253 27 7 Y 0 39 33
def COALESCE(a,'') 253 27 7 N 1 39 33
COALESCE(a,'')
1234567
# All columns must be VARCHAR(9) with the same length:
@ -5112,7 +5112,7 @@ t2 CREATE TABLE `t2` (
`IFNULL(a,'')` varchar(9) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NOT NULL,
`IF(a,a,'')` varchar(9) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci DEFAULT NULL,
`CASE WHEN a THEN a ELSE '' END` varchar(9) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci DEFAULT NULL,
`COALESCE(a,'')` varchar(9) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci DEFAULT NULL
`COALESCE(a,'')` varchar(9) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT CONCAT_WS(1,2,3) FROM t1;

149
mysql-test/main/func_hybrid_type.result
View File

@ -3430,7 +3430,7 @@ CASE WHEN TRUE THEN COALESCE(NULL) ELSE 4 END
NULL
SELECT COALESCE(COALESCE(NULL), 1.1) AS c0, IF(0, COALESCE(NULL), 1.1) AS c1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def c0 246 4 3 Y 32896 1 63
def c0 246 4 3 N 32897 1 63
def c1 246 4 3 Y 32896 1 63
c0 c1
1.1 1.1
@ -3795,8 +3795,8 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`f0` decimal(1,0) DEFAULT NULL,
`f1` decimal(1,0) DEFAULT NULL
`f0` decimal(1,0) NOT NULL,
`f1` decimal(1,0) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t1, t2;
SET sql_mode=DEFAULT;
@ -4362,3 +4362,146 @@ LEAST( CAST( 0 AS CHAR ), OLD_PASSWORD( 1 ) )
#
# End of 10.6 tests
#
#
# MDEV-36581: COALESCE() returns nullable column while IFNULL() does not
#
CREATE OR REPLACE VIEW test_coalesce_vs_ifnull AS
SELECT
COALESCE(operation_date, '1970-01-01 00:00:00') AS coalesced_date,
IFNULL(operation_date, '1970-01-01 00:00:00') AS ifnull_date
FROM (
SELECT NULL AS operation_date
) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'test_coalesce_vs_ifnull';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
coalesced_date NO varchar(19)
ifnull_date NO varchar(19)
DROP VIEW test_coalesce_vs_ifnull;
CREATE VIEW v2 as SELECT COALESCE(c, NULL) AS c_col, IFNULL(c, 10) AS i_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v2';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
c_col YES binary(0)
i_col NO varchar(2)
DROP VIEW v2;
CREATE VIEW v3 as SELECT COALESCE(c, 10, NULL) AS c_col, IFNULL(c, 10) AS i_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v3';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
c_col NO varchar(2)
i_col NO varchar(2)
DROP VIEW v3;
CREATE VIEW v4 AS SELECT COALESCE(c, NULL, NULL) as c_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v4';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
c_col YES binary(0)
DROP VIEW v4;
CREATE VIEW v5 AS SELECT COALESCE(c, COALESCE(NULL, 10), NULL) as c_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v5';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
c_col NO varchar(2)
DROP VIEW v5;
CREATE TABLE t (c1 INT, c2 DOUBLE, c3 VARCHAR(5), c4 DATE);
INSERT INTO t values (1, 2.3, 'four', '2025-05-06');
SELECT COALESCE(c1, 10) AS coalesced_c1, IFNULL(c1, 10) AS ifnull_c1 FROM t;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_c1 3 11 1 N 32897 0 63
def ifnull_c1 3 11 1 N 32897 0 63
coalesced_c1 ifnull_c1
1 1
SELECT COALESCE(c1, NULL) AS coalesced_c1, IFNULL(c1, NULL) AS ifnull_c1 FROM t;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_c1 3 11 1 Y 32896 0 63
def ifnull_c1 3 11 1 Y 32896 0 63
coalesced_c1 ifnull_c1
1 1
SELECT COALESCE(c2, NULL) AS coalesced_c2, IFNULL(c2, NULL) as ifnull_c2 FROM t;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_c2 5 22 3 Y 32896 31 63
def ifnull_c2 5 22 3 Y 32896 31 63
coalesced_c2 ifnull_c2
2.3 2.3
SELECT COALESCE(c3, 'two') as coalesced_c1, COALESCE(c4, '2025-07-08') AS coalesced_date FROM t;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_c1 253 5 4 N 1 39 8
def coalesced_date 253 10 10 N 1 39 8
coalesced_c1 coalesced_date
four 2025-05-06
INSERT INTO t values (2, 3.4, NULL, NULL);
SELECT COALESCE(c3, 'two') AS coalesced_c3, IFNULL(c3, 'three') AS ifnull_c3 FROM t WHERE c1 = 2;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_c3 253 5 3 N 1 39 8
def ifnull_c3 253 5 5 N 1 39 8
coalesced_c3 ifnull_c3
two three
SELECT COALESCE(c3, 'four', NULL) AS coalesced_c3, COALESCE(COALESCE(c3, NULL), NULL) AS coalesced_c3_null FROM t WHERE c1 = 2;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_c3 253 5 4 N 1 39 8
def coalesced_c3_null 253 5 0 Y 0 39 8
coalesced_c3 coalesced_c3_null
four NULL
SELECT COALESCE(c4, COALESCE('2025-05-06', NULL)) AS coalesced_date FROM t WHERE c1 = 2;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def coalesced_date 253 10 10 N 1 39 8
coalesced_date
2025-05-06
DROP TABLE t;
SET sql_mode='';
CREATE TABLE t1 (a UUID, b VARCHAR(32) NOT NULL);
INSERT INTO t1 VALUES (NULL, '1');
CREATE TABLE t2 AS SELECT COALESCE(a, b), IFNULL(a, b) FROM t1;
Warnings:
Warning 1292 Incorrect uuid value: '1'
Warning 1292 Incorrect uuid value: '1'
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, b)` uuid DEFAULT NULL,
`IFNULL(a, b)` uuid DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't2';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
COALESCE(a, b) YES uuid
IFNULL(a, b) YES uuid
DROP TABLE t1, t2;
CREATE TABLE t (c1 INET6, c2 INET4);
INSERT INTO t VALUES ('::', '0.0.0.0'), (NULL, NULL);
CREATE TABLE t1 AS
SELECT
COALESCE(c1, '::1') AS inet6_c1_c, IFNULL(c1, '::1') AS inet6_c1_i,
COALESCE(c2, '0.0.0.0') AS inet4_c2_c, IFNULL(c2, '0.0.0.0') AS inet4_c2_i
FROM t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't1';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
inet6_c1_c NO inet6
inet6_c1_i NO inet6
inet4_c2_c NO inet4
inet4_c2_i NO inet4
CREATE TABLE t2 AS
SELECT
COALESCE(c1, 'ipv6') AS inet6_c1_c, IFNULL(c1, 'ipv6') AS inet6_c1_i,
COALESCE(c2, 'ipv4') AS inet4_c2_c, IFNULL(c2, 'ipv4') AS inet4_c2_i
FROM t;
Warnings:
Warning 1292 Incorrect inet6 value: 'ipv6'
Warning 1292 Incorrect inet6 value: 'ipv6'
Warning 1292 Incorrect inet4 value: 'ipv4'
Warning 1292 Incorrect inet4 value: 'ipv4'
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't2';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
inet6_c1_c YES inet6
inet6_c1_i YES inet6
inet4_c2_c YES inet4
inet4_c2_i YES inet4
CREATE TABLE t3 AS SELECT COALESCE(c1, '::1') AS inet4_c1_c, IFNULL(c1, '::1') as inet6_c1_i FROM t WHERE c1 IS NULL;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't3';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
inet4_c1_c NO inet6
inet6_c1_i NO inet6
CREATE TABLE t4 AS SELECT COALESCE(c1, 'foo') AS inet4_c1_c, IFNULL(c1, 'bar') as inet6_c1_i FROM t WHERE c1 IS NOT NULL;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't3';
COLUMN_NAME IS_NULLABLE COLUMN_TYPE
inet4_c1_c NO inet6
inet6_c1_i NO inet6
DROP TABLE t, t1, t2, t3, t4;
# End of 10.11 tests

103
mysql-test/main/func_hybrid_type.test
View File

@ -1164,3 +1164,106 @@ SELECT LEAST( CAST( 0 AS CHAR ), OLD_PASSWORD( 1 ) );
--echo #
--echo # End of 10.6 tests
--echo #
--echo #
--echo # MDEV-36581: COALESCE() returns nullable column while IFNULL() does not
--echo #
CREATE OR REPLACE VIEW test_coalesce_vs_ifnull AS
SELECT
COALESCE(operation_date, '1970-01-01 00:00:00') AS coalesced_date,
IFNULL(operation_date, '1970-01-01 00:00:00') AS ifnull_date
FROM (
SELECT NULL AS operation_date
) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'test_coalesce_vs_ifnull';
DROP VIEW test_coalesce_vs_ifnull;
# Tests on views
CREATE VIEW v2 as SELECT COALESCE(c, NULL) AS c_col, IFNULL(c, 10) AS i_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v2';
DROP VIEW v2;
CREATE VIEW v3 as SELECT COALESCE(c, 10, NULL) AS c_col, IFNULL(c, 10) AS i_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v3';
DROP VIEW v3;
CREATE VIEW v4 AS SELECT COALESCE(c, NULL, NULL) as c_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v4';
DROP VIEW v4;
CREATE VIEW v5 AS SELECT COALESCE(c, COALESCE(NULL, 10), NULL) as c_col FROM (SELECT NULL AS c) AS t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'v5';
DROP VIEW v5;
# Tests on tables
CREATE TABLE t (c1 INT, c2 DOUBLE, c3 VARCHAR(5), c4 DATE);
INSERT INTO t values (1, 2.3, 'four', '2025-05-06');
--enable_metadata
--disable_ps_protocol
SELECT COALESCE(c1, 10) AS coalesced_c1, IFNULL(c1, 10) AS ifnull_c1 FROM t;
SELECT COALESCE(c1, NULL) AS coalesced_c1, IFNULL(c1, NULL) AS ifnull_c1 FROM t;
SELECT COALESCE(c2, NULL) AS coalesced_c2, IFNULL(c2, NULL) as ifnull_c2 FROM t;
SELECT COALESCE(c3, 'two') as coalesced_c1, COALESCE(c4, '2025-07-08') AS coalesced_date FROM t;
--enable_ps_protocol
--disable_metadata
INSERT INTO t values (2, 3.4, NULL, NULL);
--enable_metadata
--disable_ps_protocol
SELECT COALESCE(c3, 'two') AS coalesced_c3, IFNULL(c3, 'three') AS ifnull_c3 FROM t WHERE c1 = 2;
SELECT COALESCE(c3, 'four', NULL) AS coalesced_c3, COALESCE(COALESCE(c3, NULL), NULL) AS coalesced_c3_null FROM t WHERE c1 = 2;
SELECT COALESCE(c4, COALESCE('2025-05-06', NULL)) AS coalesced_date FROM t WHERE c1 = 2;
--enable_ps_protocol
--disable_metadata
DROP TABLE t;
# Case when one type cannot alwasy be converted to another safely
SET sql_mode='';
CREATE TABLE t1 (a UUID, b VARCHAR(32) NOT NULL);
INSERT INTO t1 VALUES (NULL, '1');
CREATE TABLE t2 AS SELECT COALESCE(a, b), IFNULL(a, b) FROM t1;
SHOW CREATE TABLE t2;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't2';
DROP TABLE t1, t2;
CREATE TABLE t (c1 INET6, c2 INET4);
INSERT INTO t VALUES ('::', '0.0.0.0'), (NULL, NULL);
CREATE TABLE t1 AS
SELECT
COALESCE(c1, '::1') AS inet6_c1_c, IFNULL(c1, '::1') AS inet6_c1_i,
COALESCE(c2, '0.0.0.0') AS inet4_c2_c, IFNULL(c2, '0.0.0.0') AS inet4_c2_i
FROM t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't1';
CREATE TABLE t2 AS
SELECT
COALESCE(c1, 'ipv6') AS inet6_c1_c, IFNULL(c1, 'ipv6') AS inet6_c1_i,
COALESCE(c2, 'ipv4') AS inet4_c2_c, IFNULL(c2, 'ipv4') AS inet4_c2_i
FROM t;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't2';
CREATE TABLE t3 AS SELECT COALESCE(c1, '::1') AS inet4_c1_c, IFNULL(c1, '::1') as inet6_c1_i FROM t WHERE c1 IS NULL;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't3';
CREATE TABLE t4 AS SELECT COALESCE(c1, 'foo') AS inet4_c1_c, IFNULL(c1, 'bar') as inet6_c1_i FROM t WHERE c1 IS NOT NULL;
SELECT COLUMN_NAME, IS_NULLABLE, COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't3';
DROP TABLE t, t1, t2, t3, t4;
--echo # End of 10.11 tests

4
mysql-test/main/gis.result
View File

@ -5014,8 +5014,8 @@ LEAST(POINT(1,1),0x60);
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
`COALESCE(0x60,POINT(1,1))` longblob DEFAULT NULL,
`COALESCE(POINT(1,1),0x60)` longblob DEFAULT NULL,
`COALESCE(0x60,POINT(1,1))` longblob NOT NULL,
`COALESCE(POINT(1,1),0x60)` longblob NOT NULL,
`LEAST(0x60,POINT(1,1))` longblob DEFAULT NULL,
`LEAST(POINT(1,1),0x60)` longblob DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci

6
mysql-test/main/null.result
View File

@ -263,11 +263,11 @@ t1 CREATE TABLE `t1` (
`c01` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c02` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c03` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci NOT NULL,
`c04` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c04` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci NOT NULL,
`c05` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c06` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c07` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c08` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c07` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci NOT NULL,
`c08` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci NOT NULL,
`c09` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c10` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,
`c11` varchar(6) CHARACTER SET latin2 COLLATE latin2_general_ci DEFAULT NULL,

4
mysql-test/main/type_bit.result
View File

@ -825,12 +825,12 @@ c
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`c` decimal(1,0) DEFAULT NULL
`c` decimal(1,0) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
SELECT COALESCE(val, 1) FROM t1;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def COALESCE(val, 1) 246 2 1 Y 32896 0 63
def COALESCE(val, 1) 246 2 1 N 32897 0 63
COALESCE(val, 1)
0
DROP TABLE t1;

6
plugin/type_inet/mysql-test/type_inet/type_inet4.result
View File

@ -481,7 +481,7 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, '0.0.0.0')` inet4 DEFAULT NULL,
`COALESCE(a, '0.0.0.0')` inet4 NOT NULL,
`LEAST(a,'0.0.0.0')` inet4 DEFAULT NULL,
`GREATEST(a,'0.0.0.0')` inet4 DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
@ -515,7 +515,7 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, 0x00000000)` inet4 DEFAULT NULL,
`COALESCE(a, 0x00000000)` inet4 NOT NULL,
`LEAST(a,0x00000000)` inet4 DEFAULT NULL,
`GREATEST(a,0x00000000)` inet4 DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
@ -1928,7 +1928,7 @@ SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a,a)` inet4 NOT NULL,
`COALESCE(a,b)` inet4 DEFAULT NULL
`COALESCE(a,b)` inet4 NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT a AS ca,a AS cb FROM t1 UNION SELECT a,b FROM t1;

6
plugin/type_inet/mysql-test/type_inet/type_inet6.result
View File

@ -475,7 +475,7 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, '::')` inet6 DEFAULT NULL,
`COALESCE(a, '::')` inet6 NOT NULL,
`LEAST(a,'::')` inet6 DEFAULT NULL,
`GREATEST(a,'::')` inet6 DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
@ -509,7 +509,7 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, 0x00000000000000000000000000000000)` inet6 DEFAULT NULL,
`COALESCE(a, 0x00000000000000000000000000000000)` inet6 NOT NULL,
`LEAST(a,0x00000000000000000000000000000000)` inet6 DEFAULT NULL,
`GREATEST(a,0x00000000000000000000000000000000)` inet6 DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
@ -2108,7 +2108,7 @@ SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a,a)` inet6 NOT NULL,
`COALESCE(a,b)` inet6 DEFAULT NULL
`COALESCE(a,b)` inet6 NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
DROP TABLE t2;
CREATE TABLE t2 AS SELECT a AS ca,a AS cb FROM t1 UNION SELECT a,b FROM t1;

6
plugin/type_test/mysql-test/type_test/type_test_double.result
View File

@ -318,9 +318,9 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`c1` test_double DEFAULT NULL,
`c2` test_double DEFAULT NULL,
`c3` test_double DEFAULT NULL
`c1` test_double NOT NULL,
`c2` test_double NOT NULL,
`c3` test_double NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
SELECT * FROM t2 ORDER BY c1;
c1 c2 c3

6
plugin/type_test/mysql-test/type_test/type_test_int8.result
View File

@ -297,9 +297,9 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`c1` test_int8(20) DEFAULT NULL,
`c2` decimal(20,1) DEFAULT NULL,
`c3` double DEFAULT NULL
`c1` test_int8(20) NOT NULL,
`c2` decimal(20,1) NOT NULL,
`c3` double NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
SELECT * FROM t2 ORDER BY c1;
c1 c2 c3

4
plugin/type_uuid/mysql-test/type_uuid/type_uuid.result
View File

@ -1567,7 +1567,7 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, '00000000-0000-0000-0000-000000000000')` uuid DEFAULT NULL,
`COALESCE(a, '00000000-0000-0000-0000-000000000000')` uuid NOT NULL,
`LEAST(a,'00000000-0000-0000-0000-000000000000')` uuid DEFAULT NULL,
`GREATEST(a,'00000000-0000-0000-0000-000000000000')` uuid DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
@ -1603,7 +1603,7 @@ FROM t1;
SHOW CREATE TABLE t2;
Table Create Table
t2 CREATE TABLE `t2` (
`COALESCE(a, 0x00000000000000000000000000000000)` uuid DEFAULT NULL,
`COALESCE(a, 0x00000000000000000000000000000000)` uuid NOT NULL,
`LEAST(a,0x00000000000000000000000000000000)` uuid DEFAULT NULL,
`GREATEST(a,0x00000000000000000000000000000000)` uuid DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci

13
sql/item_cmpfunc.h
View File

@ -1162,6 +1162,7 @@ public:
bool native_op(THD *thd, Native *to) override;
bool fix_length_and_dec(THD *thd) override
{
update_nullability_post_fix_fields();
if (aggregate_for_result(func_name_cstring(), args, arg_count, true))
return TRUE;
fix_attributes(args, arg_count);
@ -1246,17 +1247,7 @@ public:
bool native_op(THD *thd, Native *to) override;
bool fix_length_and_dec(THD *thd) override
{
/*
Set nullability from args[1] by default.
Note, some type handlers may reset maybe_null
in Item_hybrid_func_fix_attributes() if args[1]
is NOT NULL but cannot always be converted to
the data type of "this" safely.
E.g. Type_handler_inet6 does:
IFNULL(inet6_not_null_expr, 'foo') -> INET6 NULL
IFNULL(inet6_not_null_expr, '::1') -> INET6 NOT NULL
*/
copy_flags(args[1], item_base_t::MAYBE_NULL);
update_nullability_post_fix_fields();
if (Item_func_case_abbreviation2::fix_length_and_dec2(args))
return TRUE;
return FALSE;

31
sql/item_func.cc
View File

@ -291,6 +291,37 @@ bool Item_func::check_argument_types_scalar(uint start, uint end) const
}
/**
@brief
Update function's nullability based on nullness of its arguments
@details
Functions like `IFNULL` and `COALESCE` decide nullability of their
result after checking all the arguments. If any of the argument
is NOT NULL, function's result is also set to NOT NULL.
Note: Nullability determined here may be reset by type handlers in
`Item_hybrid_func_fix_attributes()`, if the first non-null argument
cannot be safely converted to target data type.
E.g. Type_handler_inet6 does:
IFNULL(inet6_not_null_expr, 'foo') -> INET6 NULL
IFNULL(inet6_not_null_expr, '::1') -> INET6 NOT NULL
*/
void Item_func::update_nullability_post_fix_fields()
{
if (!maybe_null())
return;
for (uint i= 0; i < arg_count; i++)
{
if (!args[i]->maybe_null())
{
base_flags &= ~item_base_t::MAYBE_NULL;
break;
}
}
}
/*
Resolve references to table column for a function and its argument

2
sql/item_func.h
View File

@ -85,6 +85,8 @@ protected:
return print_sql_mode_qualified_name(to, query_type, func_name_cstring());
}
void update_nullability_post_fix_fields();
public:
// Print an error message for a builtin-schema qualified function call

35
sql/sql_type_fixedbin.h
View File

@ -1589,17 +1589,40 @@ public:
- either by the most generic way in Item_func::fix_fields()
- or by Item_func_xxx::fix_length_and_dec() before the call of
Item_hybrid_func_fix_attributes()
IFNULL() is special. It does not need to test args[0].
IFNULL and COALESCE are special-
If the first non-null arg can be safely converted to result type,
the result is guaranteed to be NOT NULL
*/
uint first= dynamic_cast<Item_func_ifnull*>(attr) ? 1 : 0;
for (uint i= first; i < nitems; i++)
bool not_null_on_conversion= false;
if (dynamic_cast<Item_func_ifnull*>(attr) ||
dynamic_cast<Item_func_coalesce*>(attr))
{
if (Fbt::fix_fields_maybe_null_on_conversion_to_fbt(items[i]))
for (uint i= 0; i< nitems; i++)
{
attr->set_type_maybe_null(true);
break;
if (!items[i]->maybe_null() &&
!Fbt::fix_fields_maybe_null_on_conversion_to_fbt(items[i]))
{
not_null_on_conversion= true;
break;
}
}
}
else
{
not_null_on_conversion= true;
for (uint i= 0; i < nitems; i++)
{
if (Fbt::fix_fields_maybe_null_on_conversion_to_fbt(items[i]))
{
not_null_on_conversion= false;
break;
}
}
}
if (not_null_on_conversion)
attr->set_type_maybe_null(false);
else
attr->set_type_maybe_null(true);
return false;
}
bool Item_func_min_max_fix_attributes(THD *thd, Item_func_min_max *func,