The problem occurred when one had a subquery that had an equality X=Y where
Y referred to a named select list expression from the parent select. MySQL
crashed when trying to use the X=Y equality for ref-based access.
Fixed by allowing non-Item_field items in the described case.
called from a SELECT doesn't cause ROLLBACK of state"
Make private all class handler methods (PSEA API) that may modify
data. Introduce and deploy public ha_* wrappers for these methods in
all sql/.
This necessary to keep track of all data modifications in sql/,
which is in turn necessary to be able to optimize two-phase
commit of those transactions that do not modify data.
that the entire server uses their public ha_* counterparts instead,
since only then we can ensure proper tracing of these calls that
is necessary for Bug#12713.
A pre-requisite for Bug#12713 "Error in a stored function called from
a SELECT doesn't cause ROLLBACK of statem"
cause ROLLBACK of statement", part 1. Review fixes.
Do not send OK/EOF packets to the client until we reached the end of
the current statement.
This is a consolidation, to keep the functionality that is shared by all
SQL statements in one place in the server.
Currently this functionality includes:
- close_thread_tables()
- log_slow_statement().
After this patch and the subsequent patch for Bug#12713, it shall also include:
- ha_autocommit_or_rollback()
- net_end_statement()
- query_cache_end_of_result().
In future it may also include:
- mysql_reset_thd_for_next_command().
There were two problems when inferring the correct field types resulting from
UNION queries.
- If the type is NULL for all corresponding fields in the UNION, the resulting
type would be NULL, while the type is BINARY(0) if there is just a single
SELECT NULL.
- If one SELECT in the UNION uses a subselect, a temporary table is created
to represent the subselect, and the result type defaults to a STRING type,
hiding the fact that the type was unknown(just a NULL value).
Fixed by remembering whenever a field was created from a NULL value and pass
type NULL to the type coercion if that is the case, and creating a string field
as result of UNION only if the type would otherwise be NULL.
The index (key_part_1, key_part-2) was erroneously considered as compatible
with the required ordering in the function test_test_if_order_by_key when
a query with an ORDER BY clause contained a condition of the form
key_part_1=const OR key_part_1 IS NULL
and the order list contained only key_part_2. This happened because the value
of the const_key_parts field in the KEYUSE structure was not formed correctly
for the keys that could be used for ref_or_null access.
This was fixed in the code of the update_ref_and_keys function.
The problem could not manifest itself for MyISAM databases because the
implementation of the keys_to_use_for_scanning() handler function always
returns an empty bitmap for the MyISAM engine.
Index lookup does not always guarantee that we can
simply remove the relevant conditions from the WHERE
clause. Reasons can be e.g. conversion errors,
partial indexes etc.
The optimizer was removing these parts of the WHERE
condition without any further checking.
This leads to "false positives" when using indexes.
Fixed by checking the index reference conditions
(using WHERE) when using indexes with sub-queries.
Loose index scan does the grouping so the temp table does
not need to do it, even when sorting.
Fixed by checking if the grouping is already done before
doing sorting and grouping in a temp table and do only
sorting.
Server failed in assert() when we tried to create a DECIMAL() temp field
with a scale of more than the allowed 30. Now we limit the scale to the
allowed maximum. A truncation warning is thrown as necessary.
