Revert the patch for MDEV-9504.
It causes test failures, attempt to fix these causes more failures. The
source of all this is that the code in test_if_skip_sort_order() has
a peculiar way of treating select_limit parameter:
Correct value is computed when the query plan is changed. In other cases,
we use an approximation that ignores the presence of GROUP BY clause,
or JOINs, or both.
A patch that fixes all of the above would be too big to do in 10.1
- Legacy code would set JOIN_TAB::limit only for EXPLAIN queries (this
variable is only used when producing EXPLAIN output)
- ANALYZE/SHOW EXPLAIN need to produce EXPLAIN output for non-EXPLAIN
queries, too, so we should always set JOIN_TAB::limit.
Undo the change in test_if_skip_sort_order() that set ref_key=-1 when
a variant of index_merge is used (was made in fix for MDEV-9021).
It turned out that test_if_cheaper_ordering() call below assumes that
ref_key=-1 means "no index is used", that is, "an inefficient full table
scan is done".
This is not the same as index_merge, index_merge can actually be quite
efficient. So, ref_key=MAX_KEY denotes the fact that some index is used,
not any given index.
GENERATED BY THE EXP() FUNCTION
When generating the error message for numeric overflow, pass a flag to
Item::print() that prevents it from expanding constant expressions and
parameters to the values they evaluate to.
For consistency, also pass the flag to Item::print() when
Item_func_spatial_collection::fix_length_and_dec() generates an error
message. It doesn't make any difference at the moment, since constant
expressions haven't been evaluated yet when this function is called.
MDEV-9408 CREATE TABLE SELECT MAX(int_column) creates different columns for table vs view
There were three almost identical pieces of the code:
- Field *Item_func::tmp_table_field();
- Field *Item_sum::create_tmp_field();
- Field *create_tmp_field_from_item();
with a difference in very small details (hence the bugs):
Only Item_func::tmp_table_field() was correct, the other two were not.
Removing the two incorrect pieces of the redundant code.
Joining these three functions/methods into a single virtual method
Item::create_tmp_field().
Additionally, moving Item::make_string_field() and
Item::tmp_table_field_from_field_type() from the public into the
protected section of the class declaration, as they are now not
needed outside of Item.
that was mistakenly merged from mysql-5.5.47
(introduces valgrind failures in main.sp, because Field_varstring
columns are created as FIELD_NORMAL and that causes aria to
read bytes between the actual value length and field max length)
The following left in semi-improved state to keep patch size reasonable:
- Field operator new: left thd_alloc(current_thd)
- Sql_alloc operator new: left thd_alloc(thd_get_current_thd())
- Item_args constructors: left thd_alloc(thd)
- Item_func_interval::fix_length_and_dec(): no THD arg, have to call current_thd
- Item_func_dyncol_exists::val_int(): same
- Item_dyncol_get::val_str(): same
- Item_dyncol_get::val_int(): same
- Item_dyncol_get::val_real(): same
- Item_dyncol_get::val_decimal(): same
- Item_singlerow_subselect::fix_length_and_dec(): same
Problem:
At the end of first execution select_lex->prep_where is pointing to
a runtime created object (temporary table field). As a result
server exits trying to access a invalid pointer during second
execution.
Analysis:
While optimizing the join conditions for the query, after the
permanent transformation, optimizer makes a copy of the new
where conditions in select_lex->prep_where. "prep_where" is what
is used as the "where condition" for the query at the start of execution.
W.r.t the query in question, "where" condition is actually pointing
to a field in the temporary table. As a result, for the second
execution the pointer is no more valid resulting in server exit.
Fix:
At the end of the first execution, select_lex->where will have the
original item of the where condition.
Make prep_where the new place where the original item of select->where
has to be rolled back.
Fixed in 5.7 with the wl#7082 - Move permanent transformations from
JOIN::optimize to JOIN::prepare
Patch for 5.5 includes the following backports from 5.6:
Bugfix for Bug12603141 - This makes the first execute statement in the testcase
pass in 5.5
However it was noted later in in Bug16163596 that the above bugfix needed to
be modified. Although Bug16163596 is reproducible only with changes done for
Bug12582849, we have decided include the fix.
Considering that Bug12582849 is related to Bug12603141, the fix is
also included here. However this results in Bug16317817, Bug16317685,
Bug16739050. So fix for the above three bugs is also part of this patch.
The bitmap implementation defines two template Bitmap classes. One
optimized for 64-bit (default) wide bitmaps while the other is used for
all other widths.
In order to optimize the computations, Bitmap<64> class has defined its
own member functions for bitmap operations, the other one, however,
relies on mysys' bitmap implementation (mysys/my_bitmap.c).
Issue 1:
In case of non 64-bit Bitmap class, intersect() wrongly reset the
received bitmap while initialising a new local bitmap structure
(bitmap_init() clears the bitmap buffer) thus, the received bitmap was
getting cleared.
Fixed by initializing the local bitmap structure by using a temporary
buffer and later copying the received bitmap to the initialised bitmap
structure.
Issue 2:
The non 64-bit Bitmap class had the Iterator missing which caused
compilation failure.
Also added a cmake variable to hold the MAX_INDEXES value when supplied
from the command prompt. (eg. cmake .. -DMAX_INDEXES=128U). Checks have
been put in place to trigger build failure if MAX_INDEXES value is
greater than 128.
Test modifications:
* Introduced include/have_max_indexes_[64|128].inc to facilitate
skipping of tests for which the output differs with different
MAX_INDEXES.
* Introduced include/max_indexes.inc which would get modified by cmake
to reflect the MAX_INDEXES value used to build the server. This file
simply sets an mtr variable '$max_indexes' to show the MAX_INDEXES
value, which will then be consumed by the above introduced include file.
* Some tests (portions), dependent on MAX_INDEXES value, have been moved
to separate test files.
Issue
-----
This problem occurs when varchar columns are used in a
internal temporary table. The type of the field is set
incorrectly to the generic FIELD_NORMAL type. This in turn
results in an inaccurate calculation of the record length.
Valgrind issues will occur since initialization has not
happend for some bytes.
Fix
----
While creating the temporary table, the type of the field
needs to be to set FIELD_VARCHAR. This will allow myisam
to calculate the record length accurately.
This fix is a backport of BUG#13350136.
The problem was that GROUP BY code created Item_field objects
that referred to fields in the temp. tables used for GROUP BY.
Item_ref and set_items_ref_array() call caused pointers to temp.
table fields to occur in many places.
This patch introduces Item_temptable_field, which can handle
item->print() calls made after the underlying table is freed.
The assumption is that the engine should not need to
evaluate HAVING on the table->record[0] - the engine either
can evaluate HAVING internally before writing it to the
table->record[0], or it should leave it to the server,
that will evaluate HAVING(table->record[0]).
Similarly the engine should not need to evaluate ORDER
on the table->record[0]. Either it returns the data already
sorted, or the server will sort the table.
This task is to allow storage engines that can execute GROUP BY or
summary queries efficiently to intercept a full query or sub query from
MariaDB and deliver the result either to the client or to a temporary
table for further processing.
- Added code in sql_select.cc to intercept GROUP BY queries.
Creation of group_by_handler is done after all optimizations to allow
storage engine to benefit of an optimized WHERE clause and suggested
indexes to use.
- Added group by handler to sequence engine and a group_by test suite as
a way to test the new interface.
- Intercept EXPLAIN with a message "Storage engine handles GROUP BY"
libmysqld/CMakeLists.txt:
Added new group_by_handler files
sql/CMakeLists.txt:
Added new group_by_handler files
sql/group_by_handler.cc:
Implementation of group_by_handler functions
sql/group_by_handler.h:
Definition of group_by_handler class
sql/handler.h:
Added handlerton function to create a group_by_handler, if the storage
engine can intercept the query.
sql/item_cmpfunc.cc:
Allow one to evaluate item_equal any time.
sql/sql_select.cc:
Added code to intercept GROUP BY queries
- If all tables are from the same storage engine and the query is
using sum functions, call create_group_by() to check if the storage
engine can intercept the query.
- If yes:
- create a temporary table to hold a GROUP_BY row or result
- In do_select() intercept normal query execution by instead
calling the group_by_handler to get the result
- Intercept EXPLAIN
sql/sql_select.h:
Added handling of group_by_handler
Added caching of the original join tab (needed for cleanup after
group_by handler)
storage/sequence/mysql-test/sequence/group_by.result:
Test group_by_handler interface
storage/sequence/mysql-test/sequence/group_by.test:
Test group_by_handler interface
storage/sequence/sequence.cc:
Added simple group_by_engine for handling COUNT(*) and
SUM(primary_key). This was done as a test of the group_by_handler
interface
