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.
- Port grant_explain_non_select.{test,result} from mysql-5.6
- Per Sanja's hint, fix mysql_make_view() to take into
account that EXPLAIN now is not necessarily EXPLAIN SELECT.
- Fix a problem with EXPLAIN multi_table UPDATE:
= Do use multi_update object, because multi_update::prepare() does
various setup, e.g. it disables index-only for the tables to be updated.
= Protect multi_update::prepare() from being invoked multiple times.
If the query has subqueries, they may try to invoke it, for some reason.
Update the SHOW EXPLAIN code to work with the
new architecture (part#1):
Before, SHOW EXPLAIN operated on real query plan structures,
which meant it had to check when SELECTs are created/deleted.
SELECTs would call apc_target->enable() when they got a query
plan and disable() when their query plan was deleted.
Now, Explain data structure becomes available at once (and we
call apc_target->enable()) and then it stays until it is deleted
(when that happens, we call apc_target->disable()).
Objects of the classes Item_func_isnull and Item_func_isnotnull
must have the flag sargable set to TRUE.
Set the value of the flag sargable only in constructors of the
classes inherited from Item_int_func.
MDEV-5034:Wrong result on LEFT JOIN with a SELECT SQ or a merge view, UNION in IN subquery
Make reset null_row same as it was set in evaluate_null_complemented_join_record().
The problem was that view firlds detect null_row by not-yet-reset table.
The bug caused a memory overwrite in the function update_ref_and_keys()
It happened due to a wrong value of SELECT_LEX::cond_count. This value
historically was calculated by the fix_fields method. Now the logic of
calling this method became too complicated and, as a result, this value
is calculated not always correctly.
The patch changes the way how and when the values of SELECT_LEX::cond_count
and of SELECT_LEX::between_count are calculated. The new code does it just at
the beginning of update_ref_and_keys().
- Don't save UNION's EXPLAIN data if optimization failed with
an error. We could end up saving incomplete plan, which will
cause a crash when we attempt to print it.
Backport mysql-test/t/myisam_explain_non_select_all.test from mysql-5.6
- the .result file was modified because MariaDB choses different
query plans in a number cases. Also, we don't have some of the
"incorrect EXPLAIN output" bugs that they still have.
The .test file and includes were taken verbatim with one
exception: two tests were disabled with --disable parsing:
1. @@sql_safe_updates is not enforced EXPLAINs of multitable
updates. In MariaDB, the execution itself will produce
ER_UPDATE_WITHOUT_KEY_IN_SAFE_MODE, but EXPLAIN won't.
2. Their case #71 hits some old bug in MyISAM (See their comments
in explain_non_select.inc for details).
Do not pass PCRE_UCP flag for binary data.
This makes bytes 0x80..FF not to belong to
generic character classes \d (digit) and \w (word character).
SELECT 0xFF RLIKE '\\w';
-> 0
Note, this change does not affect non-binary data,
which is still examined with the PCRE_UCP flag by default.
For aggregated fields from views/derived tables the possible adjustment
of thd->lex->in_sum_func->max_arg_level in the function Item_field::fix_fields
must be done before we leave the function.
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.
- Make EXPLAIN UPDATE/DELETE work inside SPs
- Return correct error code from mysql_delete()
- EXPLAIN <multi-DELETE> will create a multi_delete object (as it
affects the optimization). select_result will be only used for
producing EXPLAIN output.
--replace_regex /.prefix.sql.share.charsets[/\]/MYSQL_CHARSETSDIR/
select @@global.character_sets_dir;
The intention of the '[/\]' part was to replace both slash
'/' and backslash '\\', so it does not depend on the OS.
The pattern '[/\]' was actually wrong, because ']' is escaped
and should be considered as a part of the class, instead of
being a closing bracket for the class. However, due to some bug
in the old REGEX library it worked fine.
After switching to PCRE, mysqltest correctly complains about unbalaced '[]'.
The expected correct pattern should be '[/\\]'.
However, due to some bug in mysqltest, it eats consequetive baskslashes
in a strange way, so there is no a way to have to consequetive
backslashes after unescaping.
Workaround:
using [[:punct:]] as a pattern that matches both slash and backslash,
which should be fine for this test purposes.
- Query plan footprint (in new terms, "EXPLAIN structure") should always keep
a copy of key_name. This is because the table might be a temporary table which
may be already freed by the time we use query plan footprint.
