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Fix for bug#50946: fast index creation still seems to copy the table

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Problem: ALTER TABLE ADD INDEX may lead to table copying if there's
numeric field(s) with non-default display width modificator specified.

Fix: compare numeric field's storage lenghts when we decide whether 
they can be considered 'equal' for table alteration purposes.
This commit is contained in:
Ramil Kalimullin 2010-04-25 15:06:40 +04:00
parent 9ea5576662
commit 4a1a64ec53
4 changed files with 55 additions and 3 deletions
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23
mysql-test/r/error_simulation.result
View File

@ -18,3 +18,26 @@ SELECT MAX(a) FROM t1 GROUP BY a,b;
ERROR 23000: Can't write; duplicate key in table 'tmp_table' ERROR 23000: Can't write; duplicate key in table 'tmp_table'
set tmp_table_size=default; set tmp_table_size=default;
DROP TABLE t1; DROP TABLE t1;
#
# Bug #50946: fast index creation still seems to copy the table
#
CREATE TABLE t1 (a INT(100) NOT NULL);
INSERT INTO t1 VALUES (1), (0), (2);
SET SESSION debug='+d,alter_table_only_index_change';
ALTER TABLE t1 ADD INDEX a(a);
SET SESSION debug=DEFAULT;
SHOW CREATE TABLE t1;
Table Create Table
t1 CREATE TABLE `t1` (
`a` int(100) NOT NULL,
KEY `a` (`a`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
SELECT * FROM t1;
a
0
1
2
DROP TABLE t1;
#
# End of 5.1 tests
#

16
mysql-test/t/error_simulation.test
View File

@ -33,3 +33,19 @@ set tmp_table_size=default;
DROP TABLE t1; DROP TABLE t1;
--echo #
--echo # Bug #50946: fast index creation still seems to copy the table
--echo #
CREATE TABLE t1 (a INT(100) NOT NULL);
INSERT INTO t1 VALUES (1), (0), (2);
SET SESSION debug='+d,alter_table_only_index_change';
ALTER TABLE t1 ADD INDEX a(a);
SET SESSION debug=DEFAULT;
SHOW CREATE TABLE t1;
SELECT * FROM t1;
DROP TABLE t1;
--echo #
--echo # End of 5.1 tests
--echo #

12
sql/field.cc
View File

@ -8878,14 +8878,20 @@ bool Field_num::eq_def(Field *field)
} }
/**
Check whether two numeric fields can be considered 'equal' for table
alteration purposes. Fields are equal if they are of the same type
and retain the same pack length.
*/
uint Field_num::is_equal(Create_field *new_field) uint Field_num::is_equal(Create_field *new_field)
{ {
return ((new_field->sql_type == real_type()) && return ((new_field->sql_type == real_type()) &&
((new_field->flags & UNSIGNED_FLAG) == (uint) (flags & ((new_field->flags & UNSIGNED_FLAG) ==
UNSIGNED_FLAG)) && (uint) (flags & UNSIGNED_FLAG)) &&
((new_field->flags & AUTO_INCREMENT_FLAG) == ((new_field->flags & AUTO_INCREMENT_FLAG) ==
(uint) (flags & AUTO_INCREMENT_FLAG)) && (uint) (flags & AUTO_INCREMENT_FLAG)) &&
(new_field->length <= max_display_length())); (new_field->pack_length == pack_length()));
} }

7
sql/sql_table.cc
View File

@ -6922,6 +6922,13 @@ view_err:
&candidate_key_count)) &candidate_key_count))
goto err; goto err;
DBUG_EXECUTE_IF("alter_table_only_metadata_change", {
if (need_copy_table_res != ALTER_TABLE_METADATA_ONLY)
goto err; });
DBUG_EXECUTE_IF("alter_table_only_index_change", {
if (need_copy_table_res != ALTER_TABLE_INDEX_CHANGED)
goto err; });
if (need_copy_table == ALTER_TABLE_METADATA_ONLY) if (need_copy_table == ALTER_TABLE_METADATA_ONLY)
need_copy_table= need_copy_table_res; need_copy_table= need_copy_table_res;
} }