Make Field::is_equal() const and return bool as it's a naturally fitting
type for it. Also it's agrument was narrowed to Column_definition.
InnoDB can change type of some columns by itself. InnoDB-specific code used to
reside in Field_xxx:is_equal() methods. Now engine-specific stuff was
moved to a virtual methods of handler::can_convert{string,varstring,blob,geom}.
These methods are called by Field::can_be_converted_by_engine() which is a
double dispatch pattern.
Some InnoDB-specific code still resides in compare_keys_but_name(). It should
be moved from here someday to handler::compare_key_parts(...) or similar.
IS_EQUAL_WITH_REINTERPRET_COMPATIBLE_CHARSET
IS_EQUAL_WITH_REINTERPRET_COMPATIBLE_CHARSET_BUT_COLLATE: both was removed
IS_EQUAL_NO, IS_EQUAL_YES are not needed now and should be removed
along with deprecated handler::check_if_incompatible_data().
HA_EXTENDED_TYPES_CONVERSION: was removed as such logic is not needed now by
server code.
ALTER_COLUMN_EQUAL_PACK_LENGTH: was renamed to a more generic
ALTER_COLUMN_TYPE_CHANGE_BY_ENGINE
Patch is about two cases:
1) On some collate changes it's possible to rebuild only secondary indexes
2) For non-indexed columns collate can be changed INSTANTly
Implemented mostly in Field_{string,varstring,blob}::is_equal().
Make this method return how exactly collationa differs.
This information is later used by fill_alter_inplace_info() to pass
correct info to engine.
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.
If we instantly change the size of a fixed-length field
and treat it as kind-of variable-length, then we will need
conversions between old column values and new ones.
I tried adding such a conversion to row_build(), but then I
noticed that more conversions would be needed, because
old values still appeared in a freshly rebuilt secondary index,
causing a mismatch when trying to search with the correct
longer value that was converted in my provisional fix to row_build().
So, we will revert the essential part of
MDEV-15563: Instant ROW_FORMAT=REDUNDANT column extension
(commit 22feb179ae), but not
remove any tests.
Condition can be pushed from the HAVING clause into the WHERE clause
if it depends only on the fields that are used in the GROUP BY list
or depends on the fields that are equal to grouping fields.
Aggregate functions can't be pushed down.
How the pushdown is performed on the example:
SELECT t1.a,MAX(t1.b)
FROM t1
GROUP BY t1.a
HAVING (t1.a>2) AND (MAX(c)>12);
=>
SELECT t1.a,MAX(t1.b)
FROM t1
WHERE (t1.a>2)
GROUP BY t1.a
HAVING (MAX(c)>12);
The implementation scheme:
1. Extract the most restrictive condition cond from the HAVING clause of
the select that depends only on the fields that are used in the GROUP BY
list of the select (directly or indirectly through equalities)
2. Save cond as a condition that can be pushed into the WHERE clause
of the select
3. Remove cond from the HAVING clause if it is possible
The optimization is implemented in the function
st_select_lex::pushdown_from_having_into_where().
New test file having_cond_pushdown.test is created.
This was developed by Aleksey Midenkov based on my design.
In the original InnoDB storage format (that was retroactively named
ROW_FORMAT=REDUNDANT in MySQL 5.0.3), the length of each index field
is stored explicitly.
Because of this, we can and now will allow instant conversion from
VARCHAR to CHAR or VARBINARY to BINARY of equal or greater size,
as well as instant conversion of TINYINT to SMALLINT to MEDIUMINT
to INT to BIGINT (while not changing between signed and unsigned).
Theoretically, we could allow changing from an unsigned integer to
a bigger unsigned integer, as well as changing CHAR to VARCHAR, but
that would require additional metadata and conversions whenever
reading old records.
Field_str::is_equal(), Field_varstring::is_equal(), Field_num::is_equal():
Return the new result IS_EQUAL_PACK_LENGTH_EXT if the table advertises
HA_EXTENDED_TYPES_CONVERSION capability and we are considering the
above-mentioned conversions.
ALTER_COLUMN_EQUAL_PACK_LENGTH_EXT: A new ALTER TABLE flag, similar
to ALTER_COLUMN_EQUAL_PACK_LENGTH but requiring conversions when
reading the data. The Field::is_equal() result IS_EQUAL_PACK_LENGTH_EXT
will map to this flag.
dtype_get_fixed_size_low(): For BINARY, CHAR and integer columns
in ROW_FORMAT=REDUNDANT, return 0 (variable length) from now on.
dtype_get_sql_null_size(): Keep returning the current size for
BINARY, CHAR and integer columns, so that in ROW_FORMAT=REDUNDANT
it will remain possible to update in place between NULL and NOT NULL
values.
btr_index_rec_validate(): Relax a CHECK TABLE length check for
ROW_FORMAT=REDUNDANT tables.
btr_cur_instant_init_low(): No longer trust fixed_len
for ROW_FORMAT=REDUNDANT tables.
We cannot rely on fixed_len anymore because the record can have shorter
length from before instant extension. Note that importing such tablespace
into earlier MariaDB versions produces ER_TABLE_SCHEMA_MISMATCH when
using a .cfg file.
The logic and the implementation scheme are similar with the
MDEV-9197 Pushdown conditions into non-mergeable views/derived tables
How the push down is made on the example:
select * from t1
where a>3 and b>10 and
(a,b) in (select x,max(y) from t2 group by x);
-->
select * from t1
where a>3 and b>10 and
(a,b) in (select x,max(y)
from t2
where x>3
group by x
having max(y)>10);
The implementation scheme:
1. Search for the condition cond that depends only on the fields
from the left part of the IN subquery (left_part)
2. Find fields F_group in the select of the right part of the
IN subquery (right_part) that are used in the GROUP BY
3. Extract from the cond condition cond_where that depends only on the
fields from the left_part that stay at the same places in the left_part
(have the same indexes) as the F_group fields in the projection of the
right_part
4. Transform cond_where so it can be pushed into the WHERE clause of the
right_part and delete cond_where from the cond
5. Transform cond so it can be pushed into the HAVING clause of the right_part
The optimization is made in the
Item_in_subselect::pushdown_cond_for_in_subquery() and is controlled by the
variable condition_pushdown_for_subquery.
New test file in_subq_cond_pushdown.test is created.
There are also some changes made for setup_jtbm_semi_joins().
Now it is decomposed into the 2 procedures: setup_degenerate_jtbm_semi_joins()
that is called before optimize_cond() for cond and setup_jtbm_semi_joins()
that is called after optimize_cond().
New setup_jtbm_semi_joins() is made in the way so that the result of its work is
the same as if it was called before optimize_cond().
The code that is common for pushdown into materialized derived and into materialized
IN subqueries is factored out into pushdown_cond_for_derived(),
Item_in_subselect::pushdown_cond_for_in_subquery() and
st_select_lex::pushdown_cond_into_where_clause().
Problem
=======
When facing decoding of corrupt binary log files, server may misbehave
without detecting the events corruption.
This patch makes MySQL server more resilient to binary log decoding.
Fixes for events de-serialization and apply
===========================================
@sql/log_event.cc
Query_log_event::Query_log_event: added a check to ensure query length
is respecting event buffer limits.
Query_log_event::do_apply_event: extended a debug print, added a check
to character set to determine if it is "parseable" or not, verified if
database name is valid for system collation.
Start_log_event_v3::do_apply_event: report an error on applying a
non-supported binary log version.
Load_log_event::copy_log_event: added a check to table_name length.
User_var_log_event::User_var_log_event: added checks to avoid reading
out of buffer limits.
User_var_log_event::do_apply_event: reported an sanity check error
properly and added individual sanity checks for variable types that
expect fixed (or minimum) amount of bytes to be read.
Rows_log_event::Rows_log_event: added checks to avoid reading out of
buffer limits.
@sql/log_event_old.cc
Old_rows_log_event::Old_rows_log_event: added a sanity check to avoid
reading out of buffer limits.
@sql/sql_priv.h
Added a sanity check to available_buffer() function.
* rename in_subquery_conversion_threshold to in_predicate_conversion_threshold
* make it debug-only, hide from users
* change from ulong to uint - same type and range on all architectures
As a result of this merge the code for the following tasks appears in 10.3:
- MDEV-12172 Implement tables specified by table value constructors
- MDEV-12176 Transform [NOT] IN predicate with long list of values INTO
[NOT] IN subquery.
"Optimization for equi-joins of derived tables with GROUP BY"
should be considered rather as a 'proof of concept'.
The task itself is targeted at an optimization that employs re-writing
equi-joins with grouping derived tables / views into lateral
derived tables. Here's an example of such transformation:
select t1.a,t.max,t.min
from t1 [left] join
(select a, max(t2.b) max, min(t2.b) min from t2
group by t2.a) as t
on t1.a=t.a;
=>
select t1.a,tl.max,tl.min
from t1 [left] join
lateral (select a, max(t2.b) max, min(t2.b) min from t2
where t1.a=t2.a) as t
on 1=1;
The transformation pushes the equi-join condition t1.a=t.a into the
derived table making it dependent on table t1. It means that for
every row from t1 a new derived table must be filled out. However
the size of any of these derived tables is just a fraction of the
original derived table t. One could say that transformation 'splits'
the rows used for the GROUP BY operation into separate groups
performing aggregation for a group only in the case when there is
a match for the current row of t1.
Apparently the transformation may produce a query with a better
performance only in the case when
- the GROUP BY list refers only to fields returned by the derived table
- there is an index I on one of the tables T used in FROM list of
the specification of the derived table whose prefix covers the
the fields from the proper beginning of the GROUP BY list or
fields that are equal to those fields.
Whether the result of the re-writing can be executed faster depends
on many factors:
- the size of the original derived table
- the size of the table T
- whether the index I is clustering for table T
- whether the index I fully covers the GROUP BY list.
This patch only tries to improve the chosen execution plan using
this transformation. It tries to do it only when the chosen
plan reaches the derived table by a key whose prefix covers
all the fields of the derived table produced by the fields of
the table T from the GROUP BY list.
The code of the patch does not evaluates the cost of the improved
plan. If certain conditions are met the transformation is applied.
MDEV-10134 Add full support for DEFAULT
- Added support for using tables with MySQL 5.7 virtual fields,
including MySQL 5.7 syntax
- Better error messages also for old cases
- CREATE ... SELECT now also updates timestamp columns
- Blob can now have default values
- Added new system variable "check_constraint_checks", to turn of
CHECK constraint checking if needed.
- Removed some engine independent tests in suite vcol to only test myisam
- Moved some tests from 'include' to 't'. Should some day be done for all tests.
- FRM version increased to 11 if one uses virtual fields or constraints
- Changed to use a bitmap to check if a field has got a value, instead of
setting HAS_EXPLICIT_VALUE bit in field flags
- Expressions can now be up to 65K in total
- Ensure we are not refering to uninitialized fields when handling virtual fields or defaults
- Changed check_vcol_func_processor() to return a bitmap of used types
- Had to change some functions that calculated cached value in fix_fields to do
this in val() or getdate() instead.
- store_now_in_TIME() now takes a THD argument
- fill_record() now updates default values
- Add a lookahead for NOT NULL, to be able to handle DEFAULT 1+1 NOT NULL
- Automatically generate a name for constraints that doesn't have a name
- Added support for ALTER TABLE DROP CONSTRAINT
- Ensure that partition functions register virtual fields used. This fixes
some bugs when using virtual fields in a partitioning function
Post-fix #2:
- Update test results
- Make the optimization conditional under @@optimizer_switch flag.
- The optimization is now disabled by default, so .result files
are changed back to be what they were before the MDEV-8989 patch.
Item_func_or_sum.
Implemented method update_used_tables for class Item_findow_func.
Added the flag Item::with_window_func.
Made sure that window functions could be used only in SELECT list
and ORDER BY clause.
Added test cases that checked different illegal placements of
window functions.
