The problem in this bug is when we create temporary tables. When
temporary tables are created for unions, there is some
inferrence being carried out regarding the type of the column.
Whenever this column type is inferred to be REAL (i.e. FLOAT or
DOUBLE), MySQL will always try to maintain exact precision, and
if that is not possible (there are hardware limits, since FLOAT
and DOUBLE are stored as approximate values) will switch to
using approximate values. The problem here is that at this point
the information about number of significant digits is not
available. Furthermore, the number of significant digits should
be increased for the AVG function, however, this was not properly
handled. There are 4 parts to the problem:
#1: DOUBLE and FLOAT fields don't display their proper display
lengths in max_display_length(). This is hard-coded as 53 for
DOUBLE and 24 for FLOAT. Now changed to instead return the
field_length.
#2: Type holders for temporary tables do not preserve the
max_length of the Item's from which they are created, and is
instead reverted to the 53 and 24 from above. This causes
*all* fields to get non-fixed significant digits.
#3: AVG function does not update max_length (display length)
when updating number of decimals.
#4: The function that switches to non-fixed number of
significant digits should use DBL_DIG + 2 or FLT_DIG + 2 as
cut-off values (Since fixed precision does not use the 'e'
notation)
Of these points, #1 is the controversial one, but this
change is preferred and has been cleared with Monty. The
function causes quite a few unit tests to blow up and they had
to b changed, but each one is annotated and motivated. We
frequently see the magical 53 and 24 give way to more relevant
numbers.
The problem was that during DROP TEMPORARY TABLE we tried to acquire
the name lock, though temporary tables belongs to one connection, and
no race is possible.
The solution is to not use table name locking while executing
DROP TEMPORARY TABLE.
Fixed problems in test suite where some test failed
Fixed access to not initialized memory in federated
Fixed access to not initialized memory when using BIT fields in internal temporary tables
produce warning for 'create database if not exists' if database exists
do not update database options in this case
produce warning for 'create table if not exists' if table exists
bmove_allign -> bmove_align
Added OLAP function ROLLUP
Split mysql_fix_privilege_tables to a script and a .sql data file
Added new (MEMROOT*) functions to avoid calling current_thd() when creating some common objects.
Added table_alias_charset, for easier --lower-case-table-name handling
Better SQL_MODE handling (Setting complex options also sets sub options)
New (faster) assembler string functions for x86
Made keybuff_size longlong (To make show variables work similar on 32
and 64 bit systems)
Fixed some 'not initalized variable errors' in multi-table-update.
Fixed memory leak in multi-table-update.
Now all tests works under valgrind without any errors.
Added bug fix from 3.23 for AIX 4.3.3 and gcc 3.x
Small change in EXCHANGE output
Propagate open-files-limit from mysqld_safe -> mysqld
Fixed speed bug in GROUP BY
Added quotes around database name in CREATE DATABASE db_name (for binary log)
added support for quiet
increased line buffer size
client/mysqltest.c
fixed memory leak
added query logging to result file
added error message logging to result file
added enable_query_log/disable_query_log
mysql-test/mysql-test-run.sh
converted tests to use mysqlmanager
Updated test results
