The issue here is the wrong estimate of the cardinality of a partial join,
the cardinality is too high because the function table_cond_selectivity()
returns an absurd number 100 while selectivity cannot be greater than 1.
When accessing table t by outer reference t1.a via index we do not perform any
range analysis for t. Yet we see TABLE::quick_key_parts[key] and
TABLE->quick_rows[key] contain a non-zero value though these should have been
remained untouched and equal to 0.
Thus real cause of the problem is that TABLE::init does not clean the arrays
TABLE::quick_key_parts[] and TABLE::>quick_rows[].
It should have done it because the TABLE structure created for any
instance of a table can be reused for many queries.
- Any temporary tables created under read-only mode will never be logged
to binary log. Any usage of these tables to update normal tables, even
after read-only has been disabled, will use row base logging (as the
temporary table will not be on the slave).
- Analyze, check and repair table will not be logged in read-only mode.
Other things:
- Removed not used varaibles in
MYSQL_BIN_LOG::flush_and_set_pending_rows_event.
- Set table_share->table_creation_was_logged for all normal tables.
- THD::binlog_query() now returns -1 if statement was not logged., This
is used to update table_share->table_creation_was_logged.
- Don't log admin statements in opt_readonly is set.
- Table's that doesn't have table_creation_was_logged will set binlog format to row
logging.
- Removed not needed/wrong setting of table->s->table_creation_was_logged
in create_table_from_items()
1. Removed TIMESTAMP/TRANSACTION unit auto-detection in favor of default TIMESTAMP.
Reasons:
1.1. rare practical use and doubtful advantage of such auto-detection;
1.2. it conflicts with MDEV-16226 (TRX_ID-based versioned tables performance improvement).
Needless check_unit membership removed.
2. SQL: versioning type handling refactoring
Vers_type_handler hierarchy stores versioning properties of type.
virtual Type_handler::vers() accesses specialization of
Vers_type_handler for specific type.
virtual Vers_type_handler::kind() returns versioning kind
(timestamp/trx_id).
Removed Type_handler::Vers_history_point_check_unit() in favor of
Type_handler::vers().
Renames:
require_timestamp() -> require_timestamp_error()
require_trx_id() -> require_trx_id_error()
EDIT by Alexander Barkov (@abarkov):
check_sys_fields() moved to Vers_type_handler::check_sys_fields()
* remove one level of virtual functions
* remove redundant checks
* remove an if() as the value is always known at compilation time
don't pretend that "DEFAULT expr" and "ON UPDATE DEFAULT NOW"
are "basically the same thing"
This patch allows the server to open old tables that have
"bad" generated columns (i.e. indexed virtual generated columns,
persistent generated columns) that depend on sql_mode,
for general things like SELECT, INSERT, DROP, etc.
Warning are issued in such cases.
Only these commands are now disallowed and return an error:
- CREATE TABLE introducing a "bad" generated column
- ALTER TABLE introducing a "bad" generated column
- CREATE INDEX introdicing a "bad" generated column
(i.e. adding an index on a virtual generated column
that depends on sql_mode).
Note, these commands are allowed:
- ALTER TABLE removing a "bad" generate column
- ALTER TABLE removing an index from a "bad" virtual generated column
- DROP INDEX removing an index from a "bad" virtual generated column
but only if the table does not have any "bad" columns as a result.
This patch introduces the optimization that allows range optimizer to
consider index range scans that are built employing NOT NULL predicates
inferred from WHERE conditions and ON expressions.
The patch adds a new optimizer switch not_null_range_scan.
The parser returned a syntax error message for the queries with join
expressions like this t1 JOIN t2 [LEFT | RIGHT] JOIN t3 ON ... ON ... when
the second operand of the outer JOIN operation with ON clause was another
join expression with ON clause. In this expression the JOIN operator is
right-associative, i.e. expression has to be parsed as the expression
t1 JOIN (t2 [LEFT | RIGHT] JOIN t3 ON ... ) ON ...
Such join expressions are hard to parse because the outer JOIN is
left-associative if there is no ON clause for the first outer JOIN operator.
The patch implements the solution when the JOIN operator is always parsed
as right-associative and builds first the right-associative tree. If it
happens that there is no corresponding ON clause for this operator the
tree is converted to left-associative.
The idea of the solution was taken from the patch by Martin Hansson
"WL#8083: Fixed the join_table rule" from MySQL-8.0 code line.
As the grammar rules related to join expressions in MySQL-8.0 and
MariaDB-5.5+ are quite different MariaDB solution could not borrow
any code from the MySQL-8.0 solution.
Removed Field_map, since it was used only in a single function.
Fixed is_indexed_agg_distinct(), since it relied on initialization of
Bitmap in constructor.
The MDEV-17262 commit 26432e49d3
was skipped. In Galera 4, the implementation would seem to require
changes to the streaming replication.
In the tests archive.rnd_pos main.profiling, disable_ps_protocol
for SHOW STATUS and SHOW PROFILE commands until MDEV-18974
has been fixed.
There were two newly enabled warnings:
1. cast for a function pointers. Affected sql_analyse.h, mi_write.c
and ma_write.cc, mf_iocache-t.cc, mysqlbinlog.cc, encryption.cc, etc
2. memcpy/memset of nontrivial structures. Fixed as:
* the warning disabled for InnoDB
* TABLE, TABLE_SHARE, and TABLE_LIST got a new method reset() which
does the bzero(), which is safe for these classes, but any other
bzero() will still cause a warning
* Table_scope_and_contents_source_st uses `TABLE_LIST *` (trivial)
instead of `SQL_I_List<TABLE_LIST>` (not trivial) so it's safe to
bzero now.
* added casts in debug_sync.cc and sql_select.cc (for JOIN)
* move assignment method for MDL_request instead of memcpy()
* PARTIAL_INDEX_INTERSECT_INFO::init() instead of bzero()
* remove constructor from READ_RECORD() to make it trivial
* replace some memcpy() with c++ copy assignments
This patch implements engine independent unique hash index.
Usage:- Unique HASH index can be created automatically for blob/varchar/test column whose key
length > handler->max_key_length()
or it can be explicitly specified.
Automatic Creation:-
Create TABLE t1 (a blob unique);
Explicit Creation:-
Create TABLE t1 (a int , unique(a) using HASH);
Internal KEY_PART Representations:-
Long unique key_info will have 2 representations.
(lets understand this with an example create table t1(a blob, b blob , unique(a, b)); )
1. User Given Representation:- key_info->key_part array will be similar to what user has defined.
So in case of example it will have 2 key_parts (a, b)
2. Storage Engine Representation:- In this case there will be only one key_part and it will point to
HASH_FIELD. This key_part will be always after user defined key_parts.
So:- User Given Representation [a] [b] [hash_key_part]
key_info->key_part ----^
Storage Engine Representation [a] [b] [hash_key_part]
key_info->key_part ------------^
Table->s->key_info will have User Given Representation, While table->key_info will have Storage Engine
Representation.Representation can be changed into each other by calling re/setup_keyinfo_hash function.
Working:-
1. So when user specifies HASH_INDEX or key_length is > handler->max_key_length(), In mysql_prepare_create_table
One extra vfield is added (for each long unique key). And key_info->algorithm is set to HA_KEY_ALG_LONG_HASH.
2. In init_from_binary_frm_image values for hash_keypart is set (like fieldnr , field and flags)
3. In parse_vcol_defs, HASH_FIELD->vcol_info is created. Item_func_hash is used with list of Item_fields,
When Explicit length is given by user then Item_left is used to concatenate Item_field values.
4. In ha_write_row/ha_update_row check_duplicate_long_entry_key is called which will create the hash key from
table->record[0] and then call ha_index_read_map , if we found duplicated hash , we will compare the result
field by field.
* inject portion of time updates into mysql_delete main loop
* triggered case emits delete+insert, no updates
* PORTION OF `SYSTEM_TIME` is forbidden
* `DELETE HISTORY .. FOR PORTION OF ...` is forbidden as well
