- It turns out, there are statements that will call lex_start(thd->lex)
after parsing has been finished. lex_start() will set lex->explain=NULL,
which will lose the pointer to already allocated Explain_plan object.
- To get rid of this, switch to lazy creation of lex->explain. Now, it is
created only when we get a part ot query plan.
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()).
- Generate correct contents of `Extra` column for UPDATEs/DELETEs that use quick selects
- UPDATEs with used_key_is_modified=true will show "Using buffer"
- YYPARSE_PARAM and YYLEX_PARAM are removed in Bison 3.0. Deprecated
since Bison 1.875 in favor of %lex-param, %parse-param.
- %parse-param adds an argument to yyerror() as well, updated
MYSQLerror() accordingly.
- %parse-param allows to declare proper type for argument. That's
what 99% of this patch is about.
includes:
* remove some remnants of "Bug#14521864: MYSQL 5.1 TO 5.5 BUGS PARTITIONING"
* introduce LOCK_share, now LOCK_ha_data is strictly for engines
* rea_create_table() always creates .par file (even in "frm-only" mode)
* fix a 5.6 bug, temp file leak on dummy ALTER TABLE
- Update view.result (old EXPLAIN didn't match the execution)
- Put in a stub code to work around the
SELECT ... UNION SELECT ... ORDER BY (subuqery) problem
LOAD DATA CAN CAUSE SQL INJECTION
Problem:
=======
A long SET expression in LOAD DATA is incorrectly truncated
when written to the binary log.
Analysis:
========
LOAD DATA statements are reconstructed once again before
they are written to the binary log. When SET clauses are
specified as part of LOAD DATA statement, these SET clause
user command strings need to be stored as it is inorder to
reconstruct the original user command. At present these
strings are stored as part of SET clause item tree's
top most Item node's name itself which is incorrect. As an
Item::name can be of MAX_ALIAS_NAME (256) size. Hence the
name will get truncated to "255".
Because of this the rewritten LOAD DATA statement will be
terminated incorrectly. When this statment is read back by
the mysqlbinlog tool it reads a starting single quote and
continuos to read till it finds an ending quote. Hence any
statement written post ending quote will be considered as
a new statement.
Fix:
===
As name field has length restriction the string value
should not be stored in Item::name. A new String list is
maintained to store the SET expression values and this list
is read during reconstrution.
sql/sql_lex.cc:
Clear the load data set string list during each query
execution.
sql/sql_lex.h:
Added a new String list to store the load data operation's
SET clause user command strings.
sql/sql_load.cc:
Read the SET clause user command strings from load data
set string list.
sql/sql_yacc.yy:
Store the SET caluse user command string as part of load
data set string list.
LOAD DATA CAN CAUSE SQL INJECTION
Problem:
=======
A long SET expression in LOAD DATA is incorrectly truncated
when written to the binary log.
Analysis:
========
LOAD DATA statements are reconstructed once again before
they are written to the binary log. When SET clauses are
specified as part of LOAD DATA statement, these SET clause
user command strings need to be stored as it is inorder to
reconstruct the original user command. At present these
strings are stored as part of SET clause item tree's
top most Item node's name itself which is incorrect. As an
Item::name can be of MAX_ALIAS_NAME (256) size. Hence the
name will get truncated to "255".
Because of this the rewritten LOAD DATA statement will be
terminated incorrectly. When this statment is read back by
the mysqlbinlog tool it reads a starting single quote and
continuos to read till it finds an ending quote. Hence any
statement written post ending quote will be considered as
a new statement.
Fix:
===
As name field has length restriction the string value
should not be stored in Item::name. A new String list is
maintained to store the SET expression values and this list
is read during reconstrution.
- Handle statements inside SPs:
= regular statements
= SET command, which does not have its own statement.
- Handle execution of subquery from range optimizer:
allocate subquery QPFs on the same MEM_ROOT as the whole
query plan was allocated.
Single table UPDATE/DELETE
- Correctly print type=SIMPLE vs type=PRIMARY
- Handle UPDATE/DELETE of mergeable VIEWs: we get the
VIEW's select as the first subquery.
(MySQL 5.6 doesn't print it because it finds that the
subquery is not attached to any select)
- Introduce back QueryPlan/QueryPlanFootprint separation for
single-table UPDATEs/DELETEs
- Create an empty QueryPlanFootprint for all kinds of queries
- temporary tables now works
- mysql-system_tables updated to not use temporary tables
- PASSWORD() function fixed
- Support for STATS_AUTO_RECALC, STATS_PERSISTENT and STATS_SAMPLE_PAGES table options
- Introduce "Query Plan Footprints" (abbrev. QPFs)
QPF is a part of query plan that is
1. sufficient to produce EXPLAIN output,
2. can be used to produce EXPLAIN output even after its subquery/union
was executed and deleted
3. is cheap to save so that we can always save query plans
- This patch doesn't fully address #2, we make/save strings for
a number of EXPLAIN's columns. This will be fixed.
Change of user interface to be more logical and more in line with expectations
to work similar to old-style replication.
User can now explicitly choose in CHANGE MASTER whether binlog position is
taken into account (master_gtid_pos=current_pos) or not (master_gtid_pos=
slave_pos) when slave connects to master.
@@gtid_pos is replaced by three separate variables @@gtid_slave_pos (can
be set by user, replicated GTIDs only), @@gtid_binlog_pos (read only), and
@@gtid_current_pos (a combination of the two, most recent GTID within each
domain). mysql.rpl_slave_state is renamed to mysql.gtid_slave_pos to match.
This fixes MDEV-4474.
Implement START SLAVE UNTIL master_gtid_pos = "<GTID position>".
Add test cases, including a test showing how to use this to promote
a new master among a set of slaves.
