can be specified
Currently MySQL allows one to specify what indexes to ignore during
join optimization. The scope of the current USE/FORCE/IGNORE INDEX
statement is only the FROM clause, while all other clauses are not
affected.
However, in certain cases, the optimizer
may incorrectly choose an index for sorting and/or grouping, and
produce an inefficient query plan.
This task provides the means to specify what indexes are
ignored/used for what operation in a more fine-grained manner, thus
making it possible to manually force a better plan. We do this
by extending the current IGNORE/USE/FORCE INDEX syntax to:
IGNORE/USE/FORCE INDEX [FOR {JOIN | ORDER | GROUP BY}]
so that:
- if no FOR is specified, the index hint will apply everywhere.
- if MySQL is started with the compatibility option --old_mode then
an index hint without a FOR clause works as in 5.0 (i.e, the
index will only be ignored for JOINs, but can still be used to
compute ORDER BY).
See the WL#3527 for further details.
Using INSERT DELAYED on MERGE tables could lead to table
corruptions.
The manual lists a couple of storage engines, which can be
used with INSERT DELAYED. MERGE is not in this list.
The attempt to try it anyway has not been rejected yet.
This bug was not detected earlier as it can work under
special circumstances. Most notable is low concurrency.
To be safe, this patch rejects any attempt to use INSERT
DELAYED on MERGE tables.
- Add test case that shows how slave server hangs in "STOP SLAVE"
when run on MySQL version 5.0.33 compiled with OpenSSL.
Works fine with latest version of MySQL since that problem
has been fixed by patch for bug#24148. The fix has been noted in
the changelog for MySQL 5.0.36
The flag alias_name_used was not set on for the outer references
in subqueries. It resulted in replacement of any outer reference
resolved against an alias for a full field name when the frm
representation of a view with a subquery was generated.
If the subquery and the outer query referenced the same table in
their from lists this replacement effectively changed the meaning
of the view and led to wrong results for selects from this view.
Modified several functions to ensure setting the right value of
the alias_name_used flag for outer references resolved against
aliases.
in the embedded result we don't have 'log_slave_updates OFF' line
as replication is disabled in the embedded server.
As we don't need to check for log_slave_updates variable in this
test, we can not to SHOW it at all
When the ORDER BY clause gets fixed it's allowed to search in the current
item_list in order to find aliased fields and expressions. This is ok for a
SELECT but wrong for an UPDATE statement. If the ORDER BY clause will
contain a non-existing field which is mentioned in the UPDATE set list
then the server will crash due to using of non-existing (0x0) field.
When an Item_field is getting fixed it's allowed to search item list for
aliased expressions and fields only for selects.
"Server Variables for Plugins"
Implement support for plugins to declare server variables.
Demonstrate functionality by removing InnoDB specific code from sql/*
New feature for HASH - HASH_UNIQUE flag
New feature for DYNAMIC_ARRAY - initializer accepts preallocated ptr.
Completed support for plugin reference counting.
Several problems here :
1. The conversion to double of an hex string const item
was not taking into account the unsigned flag.
2. IN was not behaving in the same was way as comparisons
when performed over an INT/DATE/DATETIME/TIMESTAMP column
and a constant. The ordinary comparisons in that case
convert the constant to an INTEGER value and do int
comparisons. Fixed the IN to do the same.
3. IN is not taking into account the unsigned flag when
calculating <expr> IN (<int_const1>, <int_const2>, ...).
Extended the implementation of IN to store and process
the unsigned flag for its arguments.
If we compare two items A and B, with B being (a constant) of a
larger type, then A gets promoted to B's type for comparison if
it's a constant, function, or CAST() column, but B gets demoted
to A's type if A is a (not explicitly CAST()) column. This is
counter-intuitive and not mandated by the standard.
Disabling optimisation where it would be lossy so field value
will properly get promoted and compared as binary string (rather
than as integers).
to return NULL for non-NULL arguments.
This is not the case as it can return NULL
for invalid hexidecimal strings.
Fixed by setting the maybe_null flag.
results)
Before this fix, the function BENCHMARK() would fail to evaluate expressions
like "(select avg(a) from t1)" in debug builds (with an assert),
or would report a time of zero in non debug builds.
The root cause is that evaluation of DECIMAL_RESULT expressions was not
supported in Item_func_benchmark::val_int().
This has been fixed by this change.
