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.
The cause of the bug is that Item_func_in::fix_fields did not fully update its
used_table_cache. This was the cause for not_null_tables in setup_conds() to be
still 0 after the call
not_null_tables= (*conds)->not_null_tables();
As a result the condition in setup_conds()
if ( ... (table->table->map & not_null_tables) ...)
failed, which was the cause for the ON expression not to be added to conds, and later
the optimizer couldn't detect that it could apply the OUTER JOIN ==> JOIN optimization.
Added test case for bug #4256.
join_outer.result:
Fixed bug #4256.
item_cmpfunc.h:
Fixed inconsistency of values of used_tables_cache and
const_item_cache for Item_func_isnull objects.
This inconsistency caused bug #4256.
Added more DBUG statements
Ensure that we are comparing end space with BINARY strings
Use 'any_db' instead of '' to mean any database. (For HANDLER command)
Only strip ' ' when comparing CHAR, not other space-like characters (like \t)
Fixed inconsistency of values of used_tables_cache
and const_item_cache for Item_func_isnull objects (bug #1990).
item_cmpfunc.h:
Fixed inconsistency of values of used_tables_cache
and const_item_cache for Item_func_isnull objects (bug #1990).
Fixed compiler warnings (a lot of hidden variables detected by the Forte compiler)
Added a lot of 'version_xxx' strings to 'show variables'
Prevent copying of TMP_TABLE_PARAM (This caused core dump bug on Solaris)
Fixed problem with printing sub selects to debug log
The objects of this class represent multiple conjunctive equalities
in where conditions: =(f1,f2,...fn) <=> f1=f2 and f2= ... and =fn.
The objects are used to generate new possibale paths to access
the tables when executing a query.
They are also used to optimize the execution plan
chosen by the optimizer for the query.
