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.
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 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
New multi-key-cache handling. This was needed becasue the old one didn't work reliable with MERGE tables.
ALTER TABLE table_name ... CHARACTER SET ... now changes all char/varchar/text columns to the given character set
(One must use ALTER TABLE ... DEFAULT CHARACTER SET ... to change the default character set)
Fixed that have_compress is detected properly (fixes problems with func_compress.test on platforms without zlib)
New syntax for CACHE INDEX ('keys' is optional if no index name is given and one mentions the key cache name only ones)
Removed compiler warnings
Added mysql_set_server_option() to allow clients like PHP to easaily set/reset the multi-statement flag.
