- When traversing JOIN_TABs with first_linear_tab/next_linear_tab(), don't forget
to enter the semi-join nest when it is the first table in the join order.
Failure to do so could cause e.g. I_S tables not to be filled.
- "ANALYZE $stmt" should discard select's output, but it should still
evaluate the output columns (otherwise, subqueries in select list
are not executed)
- SHOW EXPLAIN's code practice of calling JOIN::save_explain_data()
after JOIN::exec() is disastrous for ANALYZE, because it resets
all counters after the first execution. It is stopped
= "Late" test_if_skip_sort_order() calls explicitly update their part
of the query plan.
= Also, I had to rewrite I_S optimization to actually have optimization
and execution stages.
- First code, "EXPLAIN FORMAT=JSON stmt" and "ANALYZE FORMAT=JSON stmt"
work for basic queries. Complex constructs (e.g subqueries, etc) not
yet supported.
- No test infrastructure yet
MDEV-406: ANALYZE $stmt
- Ported the old patch to new explain code
- New SQL syntax (ANALYZE $stmt)
- ANALYZE UPDATE/DELETE is now supported (because EXPLAIN UPDATE/DELETE is supported)
- Basic counters are calculated for basic kinds of queries
(still need to see what happens with join buffer, ORDER BY...LIMIT queries, etc)
This is port of fix for MySQL BUG#17647863.
revno: 5572
revision-id: jon.hauglid@oracle.com-20131030232243-b0pw98oy72uka2sj
committer: Jon Olav Hauglid <jon.hauglid@oracle.com>
timestamp: Thu 2013-10-31 00:22:43 +0100
message:
Bug#17647863: MYSQL DOES NOT COMPILE ON OSX 10.9 GM
Rename test() macro to MY_TEST() to avoid conflict with libc++.
- The problem was that JOIN::prepare() tried to set TABLE::maybe_null
for a table in join. Non-merged semi-join tables 1) are present as
join's base tables on second EXECUTE, but 2) do not yet have a TABLE
object.
Worked around the problem by putting mixed_implicit_grouping into JOIN
object, and then passing it to JTBM tables in setup_jtbm_semi_joins().
Analysis:
st_select_lex_unit::prepare() computes can_skip_order_by as TRUE.
As a result join->prepare() gets called with order == NULL, and
doesn't do name resolution for the inner ORDER clause. Due to this
the prepare phase doesn't detect that the query references non-exiting
function and field.
Later join->optimize() calls update_used_tables() for a non-resolved
Item_field, which understandably has no Field object. This call results
in a crash.
Solution:
Resolve unnecessary ORDER BY clauses to detect if they reference non-exising
objects. Then remove such clauses from the JOIN object.
BNL and BNLH joins pre-filter the records from a joined table via JOIN_TAB::cache_select->cond.
There is no need to re-evaluate the same conditions via JOIN_TAB::select_cond. This patch removes
the duplicated conditions from the top-level conjuncts of each pushed condition.
The added "Using where" in few EXPLAINs is due to taking into account tab->cache_select->cond
in addition to tab->select_cond in JOIN::save_explain_data_intern.
Apparently in a general case a short-cut for the distinct optimization
is invalid if join buffers are used to join tables after the tables whose
values are to selected.
ORDER BY does not work
Use "dynamic" row format (instead of "block") for MARIA internal
temporary tables created for cursors.
With "block" row format MARIA may shuffle rows, with "dynamic" row
format records are inserted sequentially (there are no gaps in data
file while we fill temporary tables).
This is needed to preserve row order when scanning materialized cursors.
The patch to fix mdev-4418 turned out to be incorrect.
At the substitution of single row tables in make_join_statistics()
the used multiple equalities may change and references to the new multiple
equalities must be updated. The function remove_eq_conds() takes care of it and
it should be called right after the substitution of single row tables.
Calling it after the call of make_join_statistics was a mistake.
