and Order By
When having a UNION statement in a subquery, with no
referenced tables (or only a reference to the virtual
table 'dual'), the UNION did not allow an ORDER BY clause.
i.e:
SELECT(SELECT 1 AS a UNION
SELECT 0 AS a
ORDER BY a) AS b or
SELECT(SELECT 1 AS a FROM dual UNION
SELECT 0 as a
ORDER BY a) AS b
In addition, an ORDER BY / LIMIT clause was not accepted
in subqueries even for single SELECT statements with no
referenced tables (or with 'dual' as table reference)
i.e:
SELECT(SELECT 1 AS a ORDER BY a) AS b or
SELECT(SELECT 1 AS a FROM dual ORDER BY a) AS b
The fix was to allow an optional ORDER BY/LIMIT clause to
the grammar for these cases.
See also: Bug#57986
and Order By
When having a UNION statement in a subquery, with no
referenced tables (or only a reference to the virtual
table 'dual'), the UNION did not allow an ORDER BY clause.
i.e:
SELECT(SELECT 1 AS a UNION
SELECT 0 AS a
ORDER BY a) AS b or
SELECT(SELECT 1 AS a FROM dual UNION
SELECT 0 as a
ORDER BY a) AS b
In addition, an ORDER BY / LIMIT clause was not accepted
in subqueries even for single SELECT statements with no
referenced tables (or with 'dual' as table reference)
i.e:
SELECT(SELECT 1 AS a ORDER BY a) AS b or
SELECT(SELECT 1 AS a FROM dual ORDER BY a) AS b
The fix was to allow an optional ORDER BY/LIMIT clause to
the grammar for these cases.
See also: Bug#57986
if embedded in a SELECT
An ORDER BY clause was bound to the incorrect
(sub-)statement when used in a UNION context.
In a query like:
SELECT * FROM a UNION SELECT * FROM b ORDER BY c
the result of SELECT * FROM b is sorted, and then
combined with a. The correct behaviour is that
the ORDER BY clause should be applied on the
final set. Similar behaviour was seen on LIMIT
clauses as well.
In a UNION statement, there will be a select_lex
object for each of the two selects, and a
select_lex_unit object that describes the UNION
itself. Similarly, the same behaviour was also
seen on derived tables.
The bug was caused by using a grammar rule for
ORDER BY and LIMIT that bound these elements
to thd->lex->current_select, which points to the
last of the two selects, instead of to the
fake_select_lex member of the master select_lex_unit
object.
sql/sql_yacc.yy:
Need to use (opt_)union_order_or_limit to
bind to the correct select_lex object.
if embedded in a SELECT
An ORDER BY clause was bound to the incorrect
(sub-)statement when used in a UNION context.
In a query like:
SELECT * FROM a UNION SELECT * FROM b ORDER BY c
the result of SELECT * FROM b is sorted, and then
combined with a. The correct behaviour is that
the ORDER BY clause should be applied on the
final set. Similar behaviour was seen on LIMIT
clauses as well.
In a UNION statement, there will be a select_lex
object for each of the two selects, and a
select_lex_unit object that describes the UNION
itself. Similarly, the same behaviour was also
seen on derived tables.
The bug was caused by using a grammar rule for
ORDER BY and LIMIT that bound these elements
to thd->lex->current_select, which points to the
last of the two selects, instead of to the
fake_select_lex member of the master select_lex_unit
object.
'CREATE TABLE IF NOT EXISTS ... SELECT' behaviour
BUG#47132, BUG#47442, BUG49494, BUG#23992 and BUG#48814 will disappear
automatically after the this patch.
BUG#55617 is fixed by this patch too.
This is the 5.5 part.
It implements:
- 'CREATE TABLE IF NOT EXISTS ... SELECT' statement will not insert
anything and binlog anything if the table already exists.
It only generate a warning that table already exists.
- A couple of test cases for the behavior changing.
'CREATE TABLE IF NOT EXISTS ... SELECT' behaviour
BUG#47132, BUG#47442, BUG49494, BUG#23992 and BUG#48814 will disappear
automatically after the this patch.
BUG#55617 is fixed by this patch too.
This is the 5.5 part.
It implements:
- 'CREATE TABLE IF NOT EXISTS ... SELECT' statement will not insert
anything and binlog anything if the table already exists.
It only generate a warning that table already exists.
- A couple of test cases for the behavior changing.
Several problems fixed :
1. Non constant expressions in UNION ... ORDER BY were not correctly cleaned up
in st_select_lex_unit::cleanup() causing crashes in EXPLAIN EXTENDED because of
fields quoted by these expressions pointing to the already freed temporary table
used to calculate the UNION.
Fixed by correctly cleaning up expressions of any depth.
2. Subqueries in the order by part of UNION ... ORDER BY ... caused a crash in
EXPLAIN EXTENDED because of a transformation attempt made during EXPLAIN EXTENDED
execution. Fixed by not doing the transformation when in EXPLAIN.
3. Fulltext functions caused crash when in the ORDER BY part of an un-parenthesized
UNION that gets "promoted" to be valid for the whole union, e.g.
SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY MATCHES (a) AGAINST ('abc' IN BOOLEAN MODE).
This is a case that demonstrates a more general problem of parts of the query being
moved to another level. When doing such transformation late in the optimization run
when most of the flags about the contents of the query are already aggregated it's possible
to "split" the flags so that they correctly reflect the new queries after the transformation.
In specific the ST_SELECT_LEX::ftfunc_list is holding all the free text function for all the
parts of the second SELECT in the UNION and we don't know what part of that is in the ORDER BY
that we're to move to the UNION level and what part is about the other parts of the second SELECT.
Fixed by throwing and error when such statements are about to be processed by adding a check
for the presence of MATCH() inside the ORDER BY clause that's going to get promoted to UNION.
To workaround this new limitation one must parenthesize the UNION SELECTs and provide a real
global ORDER BY for the UNION outside of the parenthesis.
Several problems fixed :
1. Non constant expressions in UNION ... ORDER BY were not correctly cleaned up
in st_select_lex_unit::cleanup() causing crashes in EXPLAIN EXTENDED because of
fields quoted by these expressions pointing to the already freed temporary table
used to calculate the UNION.
Fixed by correctly cleaning up expressions of any depth.
2. Subqueries in the order by part of UNION ... ORDER BY ... caused a crash in
EXPLAIN EXTENDED because of a transformation attempt made during EXPLAIN EXTENDED
execution. Fixed by not doing the transformation when in EXPLAIN.
3. Fulltext functions caused crash when in the ORDER BY part of an un-parenthesized
UNION that gets "promoted" to be valid for the whole union, e.g.
SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY MATCHES (a) AGAINST ('abc' IN BOOLEAN MODE).
This is a case that demonstrates a more general problem of parts of the query being
moved to another level. When doing such transformation late in the optimization run
when most of the flags about the contents of the query are already aggregated it's possible
to "split" the flags so that they correctly reflect the new queries after the transformation.
In specific the ST_SELECT_LEX::ftfunc_list is holding all the free text function for all the
parts of the second SELECT in the UNION and we don't know what part of that is in the ORDER BY
that we're to move to the UNION level and what part is about the other parts of the second SELECT.
Fixed by throwing and error when such statements are about to be processed by adding a check
for the presence of MATCH() inside the ORDER BY clause that's going to get promoted to UNION.
To workaround this new limitation one must parenthesize the UNION SELECTs and provide a real
global ORDER BY for the UNION outside of the parenthesis.
mysql-next-mr-bugfixing.
Bug no 32858 was fixed in two different ways in what was
then called mysql 5.1 and 6.0. The fix in 6.0 was very
different since bugfix no 33204 was present. Furthermore,
the two fixes were not compatible. Hence in order to
backport Bug#33204 to the 5.1-based mysql-next-mr-bugfixing,
it was necessary to remove the 5.1 fix of 32858 and apply
the 6.0 version of the fix.
mysql-test/r/subselect.result:
Bug#33204-backport: Test result
mysql-test/r/union.result:
Bug#33204-backport:
- Reversal of test result: bugfix no 32858 for 5.1
- Application of test result: bugfix no 32858 for 6.0
mysql-test/t/subselect.test:
Bug#33204-backport:
- Changed tests
- Test case
mysql-test/t/union.test:
Bug#33204-backport:
- Reversal of test: bugfix no 32858 for 5.1
- Application of test: bugfix no 32858 for 6.0
sql/sql_class.cc:
Bug#33204-backport: Reversal of bugfix no 32858 for 5.1
sql/sql_class.h:
Bug#33204-backport: Reversal of bugfix no 32858 for 5.1
sql/sql_yacc.yy:
Bug#33204-backport:
- Reversal of bugfix no 32858 for 5.1
- Application of bugfix no 32858 for 6.0
- Application of bugfix no 33204
mysql-next-mr-bugfixing.
Bug no 32858 was fixed in two different ways in what was
then called mysql 5.1 and 6.0. The fix in 6.0 was very
different since bugfix no 33204 was present. Furthermore,
the two fixes were not compatible. Hence in order to
backport Bug#33204 to the 5.1-based mysql-next-mr-bugfixing,
it was necessary to remove the 5.1 fix of 32858 and apply
the 6.0 version of the fix.
In UNION if we use last SELECT without braces and this
SELECT have ORDER BY clause, such clause belongs to
global UNION. It is parsed like last SELECT
part and used further as 'unit->global_parameters->order_list' value.
During DESCRIBE EXTENDED we call select_lex->print_order() for
last SELECT where order fields refer to tmp table
which already freed. It leads to crash.
The fix is clean up global_parameters->order_list
instead of fake_select_lex->order_list.
mysql-test/r/union.result:
test result
mysql-test/t/union.test:
test case
sql/sql_union.cc:
In UNION if we use last SELECT without braces and this
SELECT have ORDER BY clause, such clause belongs to
global UNION. It is parsed like last SELECT
part and used further as 'unit->global_parameters->order_list' value.
During DESCRIBE EXTENDED we call select_lex->print_order() for
last SELECT where order fields refer to tmp table
which already freed. It leads to crash.
The fix is clean up global_parameters->order_list
instead of fake_select_lex->order_list.
In UNION if we use last SELECT without braces and this
SELECT have ORDER BY clause, such clause belongs to
global UNION. It is parsed like last SELECT
part and used further as 'unit->global_parameters->order_list' value.
During DESCRIBE EXTENDED we call select_lex->print_order() for
last SELECT where order fields refer to tmp table
which already freed. It leads to crash.
The fix is clean up global_parameters->order_list
instead of fake_select_lex->order_list.
UNION could convert fixed-point FLOAT(M,D)/DOUBLE(M,D) columns
to FLOAT/DOUBLE when aggregating data types from the SELECT
substatements. While there is nothing particularly wrong with
this behavior, especially when M is greater than the hardware
precision limits, it could be confusing in cases when all
SELECT statements in a union have the same
FLOAT(M,D)/DOUBLE(M,D) columns with equal precision
specifications listed in the same position.
Since the manual is quite vague on what data type should be
returned in such cases, the bug was fixed by implementing the
most 'expected' behavior: do not convert FLOAT(M,D)/DOUBLE(M,D)
to anything else if all SELECT statements in a UNION have the
same precision for that column.
mysql-test/r/union.result:
Added a test case for bug #43432.
mysql-test/t/union.test:
Added a test case for bug #43432.
sql/field.cc:
Replaced FLT_DIG+6 and DBL_DIG+7 with a symbolic constant.
sql/item.cc:
Do not convert FLOAT(M,D)/DOUBLE(M,D)
to anything else if all SELECT statements in a UNION have the
same precision for that column.
sql/mysql_priv.h:
Added a symbolic constant for FLT_DIG+6 and DBL_DIG+7.
UNION could convert fixed-point FLOAT(M,D)/DOUBLE(M,D) columns
to FLOAT/DOUBLE when aggregating data types from the SELECT
substatements. While there is nothing particularly wrong with
this behavior, especially when M is greater than the hardware
precision limits, it could be confusing in cases when all
SELECT statements in a union have the same
FLOAT(M,D)/DOUBLE(M,D) columns with equal precision
specifications listed in the same position.
Since the manual is quite vague on what data type should be
returned in such cases, the bug was fixed by implementing the
most 'expected' behavior: do not convert FLOAT(M,D)/DOUBLE(M,D)
to anything else if all SELECT statements in a UNION have the
same precision for that column.
set but is ignored".
This patch makes @@session.max_allowed_packed and
@@session.net_buffer_length read-only as suggested in the bug
report. The user will have to use SET GLOBAL (and reconnect)
to alter the session values of these variables.
The error string ER_VARIABLE_IS_READONLY is introduced.
Tests are modified accordingly.
sql/set_var.cc:
The class sys_var_thd_ulong_session_readonly is introduced as
a specialization of sys_var_thd_ulong implementing a read-only
session variable. The class overrides check() and
check_default() to achieve the read-only property for the
session part of the variable.
sql/set_var.h:
The class sys_var_thd_ulong_session_readonly is introduced as
a specialization of sys_var_thd_ulong implementing a read-only
session variable. The class overrides check() and
check_default() to achieve the read-only property for the
session part of the variable.
sql/share/errmsg.txt:
New error ER_VARIABLE_IS_READONLY.
set but is ignored".
This patch makes @@session.max_allowed_packed and
@@session.net_buffer_length read-only as suggested in the bug
report. The user will have to use SET GLOBAL (and reconnect)
to alter the session values of these variables.
The error string ER_VARIABLE_IS_READONLY is introduced.
Tests are modified accordingly.
subselects into account
It is forbidden to use the SELECT INTO construction inside UNION statements
unless on the last SELECT of the union. The parser records whether it
has seen INTO or not when parsing a UNION statement. But if the INTO was
legally used in an outer query, an error is thrown if UNION is seen in a
subquery. Fixed in 5.0 by remembering the nesting level of INTO tokens and
mitigate the error unless it collides with the UNION.
mysql-test/r/union.result:
Bug#32858: Test result
mysql-test/t/union.test:
Bug#32858: Test case
sql/sql_class.cc:
Bug#32858: Initializing new member
sql/sql_class.h:
Bug#32858: Added property nest_level to select_result class.
sql/sql_yacc.yy:
Bug#32858: The fix.
subselects into account
It is forbidden to use the SELECT INTO construction inside UNION statements
unless on the last SELECT of the union. The parser records whether it
has seen INTO or not when parsing a UNION statement. But if the INTO was
legally used in an outer query, an error is thrown if UNION is seen in a
subquery. Fixed in 5.0 by remembering the nesting level of INTO tokens and
mitigate the error unless it collides with the UNION.
into linux-st28.site:/home/martin/mysql/src/bug32848/my51-bug32848
sql/field.cc:
Auto merged
sql/field.h:
Auto merged
sql/item.cc:
Auto merged
sql/sql_select.cc:
Auto merged
mysql-test/r/union.result:
Bug#32848: Manual merge
mysql-test/t/union.test:
Bug#32848: Manual merge
into linux-st28.site:/home/martin/mysql/src/bug32848/my51-bug32848-gca
mysql-test/r/union.result:
Auto merged
mysql-test/t/union.test:
Auto merged
sql/field.h:
Auto merged
sql/sql_select.cc:
Auto merged
sql/field.cc:
Bug#32848: Manual merge
sql/item.cc:
Bug#32848: Manual merge
into linux-st28.site:/home/martin/mysql/src/bug32848/my50-bug32848
sql/field.cc:
Auto merged
sql/field.h:
Auto merged
sql/item.cc:
Auto merged
sql/sql_select.cc:
Auto merged
mysql-test/r/union.result:
Bug#32848: Manual merge
mysql-test/t/union.test:
Bug#32848: Manual merge
into magare.gmz:/home/kgeorge/mysql/work/B19390-5.1-opt
client/mysql.cc:
Auto merged
client/mysqltest.c:
Auto merged
mysql-test/r/func_gconcat.result:
Auto merged
mysql-test/suite/rpl/r/rpl_trigger.result:
Auto merged
mysql-test/suite/rpl/t/rpl_trigger.test:
Auto merged
mysql-test/t/func_gconcat.test:
Auto merged
sql/item_sum.cc:
Auto merged
sql/item_timefunc.cc:
Auto merged
sql/log.cc:
Auto merged
sql/set_var.cc:
Auto merged
sql/sp.cc:
Auto merged
sql/sql_class.cc:
Auto merged
sql/sql_class.h:
Auto merged
sql/unireg.cc:
Auto merged
mysql-test/r/union.result:
Merged bug 27848 to 5.1-opt
mysql-test/t/union.test:
Merged bug 27848 to 5.1-opt
sql/sql_yacc.yy:
Merged bug 27848 to 5.1-opt
into linux-st28.site:/home/martin/mysql/src/bug32858/my50-bug32858-push
sql/sql_class.cc:
Auto merged
sql/sql_class.h:
Auto merged
sql/sql_yacc.yy:
Auto merged
mysql-test/r/union.result:
Bug#32858: Manual merge
mysql-test/t/union.test:
Bug#32858: Manual merge
In a union without braces, the order by at the end is applied to the
overall union. It therefore should not interfere with the individual
select parts of the union.
Fixed by changing our parser rules appropriately.
mysql-test/r/union.result:
Added a test case for bug #27848.
mysql-test/t/union.test:
Added a test case for bug #27848.
In a union without braces, the order by at the end is applied to the
overall union. It therefore should not interfere with the individual
select parts of the union.
Fixed by changing our parser rules appropriately.
subselects into account
It is forbidden to use the SELECT INTO construction inside UNION statements
unless on the last SELECT of the union. The parser records whether it
has seen INTO or not when parsing a UNION statement. But if the INTO was
legally used in an outer query, an error is thrown if UNION is seen in a
subquery. Fixed in 5.0 by remembering the nesting level of INTO tokens and
mitigate the error unless it collides with the UNION.
mysql-test/r/union.result:
Bug#32858: Test result
mysql-test/t/union.test:
Bug#32858: Test case
sql/sql_class.cc:
Bug#32858: Initializing new member
sql/sql_class.h:
Bug#32858: Added property nest_level to select_result class.
sql/sql_yacc.yy:
Bug#32858: The fix.
subselects into account
It is forbidden to use the SELECT INTO construction inside UNION statements
unless on the last SELECT of the union. The parser records whether it
has seen INTO or not when parsing a UNION statement. But if the INTO was
legally used in an outer query, an error is thrown if UNION is seen in a
subquery. Fixed in 5.0 by remembering the nesting level of INTO tokens and
mitigate the error unless it collides with the UNION.
