After FLUSH STATUS max_used_connections was reset to 0, and haven't
been updated while cached threads were reused, until the moment a new
thread was created.
The first suggested fix from original bug report was implemented:
a) On flushing the status, set max_used_connections to
threads_connected, not to 0.
b) Check if it is necessary to increment max_used_connections when
taking a thread from the cache as well as when creating new threads
The problem was due to the fact that with --lower-case-table-names set to 1
the function find_field_in_group did not convert the prefix 'HU' in
HU.PROJ.CITY into lower case when looking for it in the group list. Yet the
names in the group list were extended by the database name in lower case.
counter".
When TRUNCATE TABLE was called within an stored procedure the
auto_increment counter was not reset to 0 even if straight
TRUNCATE for this table did this.
This fix makes TRUNCATE in stored procedures to be handled exactly
in the same way as straight TRUNCATE. We achieve this by rolling
back the fix for bug 8850, which is no longer needed since stored
procedures don't require prelocked mode anymore (and TRUNCATE is
not allowed in stored functions or triggers).
The wrong value was being reported as the field_length for BIT
fields, resulting in confusion for at least Connector/J. The
field_length is now always the number of bits in the field, as
it should be.
The bug was caused by wrong behaviour of mysql_insert() which in case
of INSERT DELAYED into a view exited with thd->net.report_error == 0.
This blocked error reporting to the client which started waiting
infinitely for response to the query.
The code in opt_sum_query that prevented the COUNT/MIN/MAX
optimization from being applied to outer joins was not adjusted
after introducing nested joins. As a result if an outer join
contained a reference to a view as an inner table the code of
opt_sum_query missed the presence of an on expressions and
erroneously applied the mentioned optimization.
Multiple equalities were not adjusted after reading constant tables.
It resulted in neglecting good index based methods that could be
used to access of other tables.
The bug was due to a missed case in the detection of whether an index
can be used for loose scan. More precisely, the range optimizer chose
to use loose index scan for queries for which the condition(s) over
an index key part could not be pushed to the index together with the
loose scan.
As a result, loose index scan was selecting the first row in the
index with a given GROUP BY prefix, and was applying the WHERE
clause after that, while it should have inspected all rows with
the given prefix, and apply the WHERE clause to all of them.
The fix detects and skips such cases.
out of a nested join to the on conditions for the nest.
The bug happened due to:
1. The function simplify_joins could change on expressions for nested joins.
Yet modified on expressions were not saved in prep_on_expr.
2. On expressions were not restored for nested joins in
reinit_stmt_before_use.
The GROUP_CONCAT uses its own temporary table. When ROLLUP is present
it creates the second copy of Item_func_group_concat. This copy receives the
same list of arguments that original group_concat does. When the copy is
set up the result_fields of functions from the argument list are reset to the
temporary table of this copy.
As a result of this action data from functions flow directly to the ROLLUP copy
and the original group_concat functions shows wrong result.
Since queries with COUNT(DISTINCT ...) use temporary tables to store
the results the COUNT function they are also affected by this bug.
The idea of the fix is to copy content of the result_field for the function
under GROUP_CONCAT/COUNT from the first temporary table to the second one,
rather than setting result_field to point to the second temporary table.
To achieve this goal force_copy_fields flag is added to Item_func_group_concat
and Item_sum_count_distinct classes. This flag is initialized to 0 and set to 1
into the make_unique() member function of both classes.
To the TMP_TABLE_PARAM structure is modified to include the similar flag as
well.
The create_tmp_table() function passes that flag to create_tmp_field().
When the flag is set the create_tmp_field() function will set result_field
as a source field and will not reset that result field to newly created
field for Item_func_result_field and its descendants. Due to this there
will be created copy func to copy data from old result_field to newly
created field.
A table with an on insert trigger was reported as crashed when the insert
was processed with bulk insert mode on (handler::start_bulk_insert).
The trigger was also selecting from the same table, and that caused
the "crash".
The same problem was present when an insert statement, which was processed
in bulk mode, also used a stored function that was reading the same table.
This fix disables bulk inserts if a statement uses functions or invokes
triggers. Implementing more granular checks will require much more code and
therefore can hardly be done in 5.0
