* Added Item_ref::set_properties
* Item_ref::Item_ref now expects to get in *item either
NULL - then fix_fields() will be called later or
ptr to Item it will refer to - then an equivalent of fix_fields() call is performed
The problem in 4.1 was the same as in 4.0 - fix_fields() not called for created Item_ref.
The fix is similar too - initialize Item_refs in ctor (but don't interfere with cases when
Item_ref is used by subselects).
out of order". (final version)
Now instead of binding Item_trigger_field to TABLE objects during
trigger definition parsing at table open, we perform pass through
special list of all such objects in trigger. This allows easily check
all references to fields in old/new version of row in trigger during
execution of CREATE TRIGGER statement (this is more courtesy for users
since we can't check everything anyway).
We also report that such reference is bad by returning error from
Item_trigger_field::fix_fields() method (instead of setup_field())
This means that if trigger is broken we will bark during trigger
execution instead of trigger definition parsing at table open.
(i.e. now we allow to open tables with broken triggers).
of <parameter> IS NULL":
we must not only set Item::null_value in Item_param, but implement
Item_param::is_null() to work well with IS NULL/IS NOT NULL clauses.
the result takes its charset/collation
attributes from the character string,
e.g. SELECT func(NULL, _latin2'string')
now returns a latin2 result. This is
done by introducing a new derivation
(aka coercibility) level DERIVATION_IGNORABLE,
which is used with Item_null.
2. 'Pure' NULL is now BINARY(0), not CHAR(0).
I.e. NULL is now more typeless.
FOUND is not a reserved keyword anymore
Added Item_field::set_no_const_sub() to be able to mark fields that can't be substituted
Added 'simple_select' method to be able to quickly determinate if a select_result is a normal SELECT
Note that the 5.0 tree is not yet up to date: Sanja will have to fix multi-update-locks for this merge to be complete
constant with a column. The string is converted into the column
character set. It conversion doesn't lose data, then operation
is possible. Otherwise, give an error, as it was earlier.
Added the code processing on expressions for applying
multiple equalities.
sql_select.cc:
Post-merge fixes for Item_equal patch.
Added the code processing on expressions for applying
multiple equalities.
Many files:
Post-merge fixes for Item_equal patch.
item_cmpfunc.cc:
Post-merge fixes for Item_equal patch.
Fixed a problem when an equality field=const cannot be applied to
the predicate P(field,c) for constant propagation as a conversion
of field is needed.
item.h, item.cc:
Fixed a problem when an equality field=const cannot be applied to
the predicate P(field,c) for constant propagation as a conversion
of field is needed.
A fix for Bug#6042 "constants propogation works olny once (prepared
statements)": reset item->marker in Item::cleanup, as it's used
in propogate_cond_constants. No test case as the only way I could
come up with to show the problem is EXPLAIN, and EXPLAIN is painful
to use in the test suite.
crashes server (prepared statements)": the bug was that all boolean
items always recovered its original arguments at statement cleanup
stage.
This collided with Item_subselect::select_transformer, which tries to
permanently change the item tree to use a transformed subselect instead of
original one.
So we had this call sequence for prepare:
mysql_stmt_prepare -> JOIN::prepare ->
Item_subselect::fix_fields -> the item tree gets transformed ->
Item_bool_rowready_func2::cleanup, item tree is recovered to original
state, while it shouldn't have been;
mysql_stmt_execute -> attempts to execute a broken tree -> crash.
Now instead of bluntly recovering all arguments of bool functions in
Item_bool_rowready_func2::cleanup, we recover only those
which were changed, and do it in one place.
There still would exist a possibility for a collision with subselect
tranformation, if permanent and temporary changes were performed at the
same stage.
But fortunately subselect transformation is always done first, so it
doesn't conflict with the optimization done by propogate_cond_constants.
Now we have:
mysql_stmt_prepare -> JOIN::prepare -> subselect transformation
permanently changes the tree -> cleanup doesn't recover anything,
because nothing was registered for recovery.
mysql_stmt_execute -> JOIN::prepare (the tree is already transformed,
so it doesn't change), JOIN::optimize ->
propogate_cond_constants -> temporary changes the item tree
with constants -> JOIN::execute -> cleanup ->
the changes done by propogate_cond_constants are recovered, as
they were registered for recovery.
