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'#--------------------FN_DYNVARS_097_01-------------------------#'
SET @start_value = @@global.myisam_stats_method;
SET @@global.myisam_stats_method = nulls_equal;
'connect (con1,localhost,root,,,,)'
'connection con1'
SELECT @@global.myisam_stats_method;
@@global.myisam_stats_method
nulls_equal
SELECT @@session.myisam_stats_method;
@@session.myisam_stats_method
nulls_equal
'#--------------------FN_DYNVARS_097_02-------------------------#'
'connection default'
DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT, KEY (a));
INSERT INTO t1 VALUES (0),(1),(2),(3),(4);
INSERT INTO t1 SELECT NULL FROM t1;
'default: NULLs considered unequal'
SET myisam_stats_method = nulls_unequal;
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 10 NULL NULL YES BTREE
INSERT INTO t1 VALUES (11);
DELETE FROM t1 WHERE a = 11;
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 10 NULL NULL YES BTREE
'Set nulls to be equal'
SET myisam_stats_method = nulls_equal;
INSERT INTO t1 VALUES (11);
DELETE FROM t1 WHERE a = 11;
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 5 NULL NULL YES BTREE
INSERT INTO t1 VALUES (11);
DELETE FROM t1 WHERE a = 11;
CHECK TABLE t1;
Table Op Msg_type Msg_text
test.t1 check status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 5 NULL NULL YES BTREE
'Set nulls to be ignored'
SET myisam_stats_method = nulls_ignored;
SHOW VARIABLES LIKE 'myisam_stats_method';
Variable_name Value
myisam_stats_method nulls_ignored
DROP TABLE t1;
CREATE TABLE t1 (
a CHAR(3), b CHAR(4), c CHAR(5), d CHAR(6),
KEY(a,b,c,d)
);
INSERT INTO t1 VALUES ('bcd','def1', NULL, 'zz');
INSERT INTO t1 VALUES ('bcd','def2', NULL, 'zz');
INSERT INTO t1 VALUES ('bce','def1', 'yuu', NULL);
INSERT INTO t1 VALUES ('bce','def2', NULL, 'quux');
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 2 NULL NULL YES BTREE
t1 1 a 2 b A 4 NULL NULL YES BTREE
t1 1 a 3 c A 4 NULL NULL YES BTREE
t1 1 a 4 d A 4 NULL NULL YES BTREE
DELETE FROM t1;
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
SHOW INDEX FROM t1;
Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment
t1 1 a 1 a A 0 NULL NULL YES BTREE
t1 1 a 2 b A 0 NULL NULL YES BTREE
t1 1 a 3 c A 0 NULL NULL YES BTREE
t1 1 a 4 d A 0 NULL NULL YES BTREE
SET myisam_stats_method = DEFAULT;
DROP TABLE t1;
SET @@global.myisam_stats_method= @start_value;