This is an additional fix.
Item::val_xxx methods are supposed to use original data source and
Item::val_xxx_result methods to use the item's result field. But for the
Item_func_set_user_var class val_xxx_result methods were mapped to val_xxx
methods. This leads, in particular, to producing bad sort keys and thus
wrong order of the result set of queries with group by/order by clauses.
The set of val_xxx_result methods is added to the Item_func_set_user_var
class. It's the same as the val_xxx set of method but uses the result_field
to return a value.
The end_update() function uses the Item::save_org_in_field() function to
save original values of items into the group buffer. But for the
Item_func_set_user_var this method was mapped to the save_in_field method.
The latter function wrongly decides to use the result_field. This leads to
saving incorrect value in the grouping buffer and wrong result of the whole
query.
The can_use_result_field argument of the bool type is added to the
Item_func_set_user_var::save_in_field() function. If it is set to FALSE
then the item's result field won't be used. Otherwise it will be detected
whether the result field will be used (old behaviour).
Two wrapping functions for the function above are added to the
Item_func_set_user_var class:
the save_in_field(Field *field, bool no_conversions) - it calls the above
function with the can_use_result_field set to TRUE.
the save_org_in_field(Field *field) - same, but the can_use_result_field
is set to FALSE.
- Adding variable m_cached_result_type to keep the variable type consistent
during the execution of a statement.
- Before each result set is returned to the client the description of each
column is sent as meta data.
Previously the result type for a column could change if the hash variable
entry changed between statements. This caused the result set of the query
to alternate column types in certain cases which is not supported by MySQL
client-server protocol. Example:
Previously this sequence:
SET @a:=1;
SELECT @a:="text", @a;
would return "text", "text";
After the change the SELECT returns "text", 0
The reson for this is that previously the result set from 'SELECT @a;'
would always be of the type STRING, whereas now the type of the variable
is taken from the last SET statement. However, 'SELECT @a:="text"' will
return type of STRING since the right side of the assignment is used.
used.
The Item::save_in_field() function is called from fill_record() to fill the
new row with data while execution of the CREATE TABLE ... SELECT statement.
Item::save_in_field() calls val_xxx() methods in order to get values.
val_xxx() methods do not take into account the result field. Due to this
Item_func_set_user_var::val_xxx() methods returns values from the original
table, not from the temporary one.
The save_in_field() member function is added to the Item_func_set_user_var
class. It detects whether the result field should be used and properly updates
the value of the user variable.
used.
Sorting by RAND() uses a temporary table in order to get a correct results.
User defined variable was set during filling the temporary table and later
on it is substituted for its value from the temporary table. Due to this
it contains the last value stored in the temporary table.
Now if the result_field is set for the Item_func_set_user_var object it
updates variable from the result_field value when being sent to a client.
The Item_func_set_user_var::check() now accepts a use_result_field
parameter. Depending on its value the result_field or the args[0] is used
to get current value.
Gluh's SESSION/GLOBAL for @variables fix in sql_yacc.yy and
Bar's well_formed_len() changes in ndb code
did not make it and should be re-applied manually
Now one can use user variables as target for data loaded from file
(besides table's columns). Also LOAD DATA got new SET-clause in which
one can specify values for table columns as expressions.
For example the following is possible:
LOAD DATA INFILE 'words.dat' INTO TABLE t1 (a, @b) SET c = @b + 1;
This patch also implements new way of replicating LOAD DATA.
Now we do it similarly to other queries.
We store LOAD DATA query in new Execute_load_query event
(which is last in the sequence of events representing LOAD DATA).
When we are executing this event we simply rewrite part of query which
holds name of file (we use name of temporary file) and then execute it
as usual query. In the beggining of this sequence we use Begin_load_query
event which is almost identical to Append_file event
independently from the expression it is initialized from.
In other words, this change treats a user variable like
a table with one column and one record. Discussed with
PeterG, Serg and Lars. This change also simplifies replication
allowing not to replicate variables' coercibility.
Ensure that references in HAVING, ORDER BY or GROUP BY are calculated after fields in SELECT.
This will ensure that any reference to these has a valid value.
Generalized the code for split_sum_func()
