LEX, st_select_lex, st_select_unit optimized for space:
- Use bit fields for bool variables
- Ensure that all bit fields are initialized (improves
performance for init functions as all bit fields can be
initalized with one memory access)
- Move members around in above structures to remove alignment
gaps
Some savings:
LEX: 7032 -> 6880
THD: 25608 -> 25456
st_select_lex_unit: 2048 -> 2008
LEX::start(): 1321 -> 1245 instructions
st_select_lex_unit::init_query() 284 -> 214 instructions
st_select_lex::init_query(): 766 -> 692 instructions
st_select_lex::init_select(): 563 -> 540 instructions
Other things:
- Removed not used LEX::select_allow_into
- Fixed MDEV-25510 Assertion `sel->select_lock ==
st_select_lex::select_lock_type::NONE' which was caused by this commit.
plugin variables in SET only locked the plugin till the end of the
statement. If SET with a plugin variable was prepared, it was possible
to uninstall the plugin before EXECUTE. Then EXECUTE would crash,
trying to resolve a now-invalid pointer to a disappeared variable.
Fix: keep plugins locked until the prepared statement is closed.
Before FRM is written walk vcol expressions through
check_table_name_processor() and check if field items match (db,
table_name) qualifier.
We cannot do this in check_vcol_func_processor() as there is already
no table name qualifiers in expressions of written and loaded FRM.
Before this patch mergeable derived tables / view used in a multi-table
update / delete were merged before the preparation stage.
When the merge of a derived table / view is performed the on expression
attached to it is fixed and ANDed with the where condition of the select S
containing this derived table / view. It happens after the specification of
the derived table / view has been merged into S. If the ON expression refers
to a non existing field an error is reported and some other mergeable derived
tables / views remain unmerged. It's not a problem if the multi-table
update / delete statement is standalone. Yet if it is used in a stored
procedure the select with incompletely merged derived tables / views may
cause a problem for the second call of the procedure. This does not happen
for select queries using derived tables / views, because in this case their
specifications are merged after the preparation stage at which all ON
expressions are fixed.
This patch makes sure that merging of the derived tables / views used in a
multi-table update / delete statement is performed after the preparation
stage.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
Replace
* select_lex::offset_limit
* select_lex::select_limit
* select_lex::explicit_limit
with select_lex::Lex_select_limit
The Lex_select_limit already existed with the same elements and was used in
by the yacc parser.
This commit is in preparation for FETCH FIRST implementation, as it
simplifies a lot of the code.
Additionally, the parser is simplified by making use of the stack to
return Lex_select_limit objects.
Cleanup of init_query() too. Removes explicit_limit= 0 as it's done a bit later
in init_select() with limit_params.empty()
(Also fixes MDEV-25254).
Re-work Name Resolution for the argument of JSON_TABLE(json_doc, ....)
function. The json_doc argument can refer to other tables, but it can
only refer to the tables that precede[*] the JSON_TABLE(...) call.
[*] - For queries with RIGHT JOINs, the "preceding" is determined after
the query is normalized by converting RIGHT JOIN into left one.
The implementation is as follows:
- Table function arguments use their own Name_resolution_context.
- The Name_resolution_context now has a bitmap of tables that should be
ignored when searching for a field.
- get_disallowed_table_deps() walks the TABLE_LIST::nested_join tree
and computes a bitmap of tables that do not "precede" the given
JSON_TABLE(...) invocation (according the above definition of
"preceding").
At the second execution of the PS
1. mark_as_dependent() is called with the same parameters as at the first
execution (select#4 and select#3)
2. as outer_select (select#3) has been already merged at the first
execution of PS it cannot be reached using the outer_select() function
anymore (and so can not stop iteration).
3. as a result all selects towards the top level select including the
select for 'ca' are marked as uncacheable.
4. Marked uncacheable it executed incorrectly triggering filling its
temporary table several times and using freed memory at the end.
To avoid the problem we use name resolution context to go "up".
NOTE: problem also exists in 10.2 but has no visible effect on execution.
That is why the problem is fixed in 10.2.
The patch also add debug logging of important procedures and
better specify parameters types of st_select_lex::mark_as_dependent.
Adds an implementation for SELECT ... FOR UPDATE SKIP LOCKED /
SELECT ... LOCK IN SHARED MODE SKIP LOCKED
This is implemented only InnoDB at the moment, not in RockDB yet.
This adds a new hander flag HA_CAN_SKIP_LOCKED than
will be used when the storage engine advertises the flag.
When a storage engine indicates this flag it will get
TL_WRITE_SKIP_LOCKED and TL_READ_SKIP_LOCKED transaction types.
The Lex structure has been updated to store both the FOR UPDATE/LOCK IN
SHARE as well as the SKIP LOCKED so the SHOW CREATE VIEW
implementation is simplier.
"SELECT FOR UPDATE ... SKIP LOCKED" combined with CREATE TABLE AS or
INSERT.. SELECT on the result set is not safe for STATEMENT based
replication. MIXED replication will replicate this as row based events."
Thanks to guidance from Facebook commit
193896c466
This helped verify basic test case, and components that need implementing
(even though every part was implemented differently).
Thanks Marko for guidance on simplier InnoDB implementation.
Reviewers: Marko, Monty
The bug caused crashes of the server when processing queries with nested
table value constructors (TVC) . It happened because the grammar rules to
parse TVC used the same global lists for both nested TVC and nesting TVC.
As a result invalid select trees were constructed for queries with nested
TVC and this led to crashes at the prepare stage.
This patch provides its own lists structures for each TVC nest level.
Besides the patch fixes a bug in the function wrap_tvc() that missed
inheritance of the SELECT_LEX::exclude_from_table_unique_test for
selects that wrapped TVCs. This inheritance is critical for specifications
of derived tables that employ nested TVCs.
Approved by dmitry.shulga@mariadb.com
This bug caused crashes of the server when processing queries with table
value constructors (TVC) that contained subqueries and were used itself as
subselects. For such TVCs the following transformation is applied at the
prepare stage:
VALUES (v1), ... (vn) => SELECT * FROM (VALUES (v1), ... (vn)) tvc_x.
This transformation allows to reduce the problem of evaluation of TVCs used
as subselects to the problem of evaluation of regular subselects.
The transformation is implemented in the wrap_tvc(). The code the function
to mimic the behaviour of the parser when processing the result of the
transformation. However this imitation was not free of some flaws. First
the function called the method exclude() that completely destroyed the
select tree structures below the transformed TVC. Second the function
used the procedure mysql_new_select to create st_select_lex nodes for
both wrapping select of the transformation and TVC. This also led to
constructing of invalid select tree structures.
The patch actually re-engineers the code of wrap_tvc().
Approved by Oleksandr Byelkin <sanja@mariadb.com>
Problem:
========
CHANGE MASTER TO MASTER_USER='root', MASTER_SSL=0, MASTER_SSL_CA='',
MASTER_SSL_CERT='', MASTER_SSL_KEY='', MASTER_SSL_CRL='',
MASTER_SSL_CRLPATH='';
CHANGE MASTER TO MASTER_USER='root', MASTER_PASSWORD='', MASTER_SSL=0;
use-after-poison is reported for lex_mi->ssl_crl
File: sql_repl.cc
if (lex_mi->ssl_crl)
strmake_buf(mi->ssl_crl, lex_mi->ssl_crl);
Analysis:
========
At the end of CHANGE MASTER statement execution, the LEX_MASTER_INFO
parameters are reset so that the next query will have a clean state. But
'ssl_crl' and 'ssl_crl_path' members of LEX_MASTER_INFO object are not
cleared during 'LEX_MASTER_INFO::reset'. Hence when a new CHANGE MASTER
statement is executed, the stale value of lex_mi->ssl_crl is used, so ASAN
reports use-after-poison.
Fix:
===
Clear 'ssl_crl' and 'ssl_crl_path' as part of 'reset'.
- Adding optional qualifiers to data types:
CREATE TABLE t1 (a schema.DATE);
Qualifiers now work only for three pre-defined schemas:
mariadb_schema
oracle_schema
maxdb_schema
These schemas are virtual (hard-coded) for now, but may turn into real
databases on disk in the future.
- mariadb_schema.TYPE now always resolves to a true MariaDB data
type TYPE without sql_mode specific translations.
- oracle_schema.DATE translates to MariaDB DATETIME.
- maxdb_schema.TIMESTAMP translates to MariaDB DATETIME.
- Fixing SHOW CREATE TABLE to use a qualifier for a data type TYPE
if the current sql_mode translates TYPE to something else.
The above changes fix the reported problem, so this script:
SET sql_mode=ORACLE;
CREATE TABLE t2 AS SELECT mariadb_date_column FROM t1;
is now replicated as:
SET sql_mode=ORACLE;
CREATE TABLE t2 (mariadb_date_column mariadb_schema.DATE);
and the slave can unambiguously treat DATE as the true MariaDB DATE
without ORACLE specific translation to DATETIME.
Similar,
SET sql_mode=MAXDB;
CREATE TABLE t2 AS SELECT mariadb_timestamp_column FROM t1;
is now replicated as:
SET sql_mode=MAXDB;
CREATE TABLE t2 (mariadb_timestamp_column mariadb_schema.TIMESTAMP);
so the slave treats TIMESTAMP as the true MariaDB TIMESTAMP
without MAXDB specific translation to DATETIME.
