This follows up commit
commit 94a520ddbe and
commit 7c5519c12d.
After these changes, the default test suites on a
cmake -DWITH_UBSAN=ON build no longer fail due to passing
null pointers as parameters that are declared to never be null,
but plenty of other runtime errors remain.
Reimplement MDEV-14275 Improving memory utilization for information schema
Postpone temp table instantiation until after setup_fields().
Replace all unused (not marked in read_set) columns in an I_S table
with CHAR(0). This can drastically reduce the footprint of a MEMORY
table (a TABLE_CATALOG alone is 1538 bytes per row).
This does not change the engine. If the table was decided to be Aria
(because of, say, blobs) then after optimization it'll stay Aria
even if all blobs were removed.
Note 1: when transforming table structure, share->blob_fields is
preserved, otherwise Aria might switch from DYNAMIC to STATIC row format
and expect a special field for a deleted mark, which create_tmp_tabe
didn't provide.
Note 2: optimizer was doing handler::info() (to know the number of rows)
before the temp table is populated. That didn't make much sense. Now
it's done before the table is even instantiated. Preserve the old
behavior and report 0 rows.
This reverts e2664ee836 and a8458a2345
In case of NATURAL JOIN / USING mark all field (one table can not be opened
in any case so optimisation does not worth it).
IMHO table should be checked for used fields and filled after prepare,
when we will fave whole info about used fields but it is too big change
for a bugfix. Which will be made later by Serg patch
* Allocate items on thd->mem_root while refixing vcol exprs
* Make vcol tree changes register and roll them back after the statement is executed.
Explanation:
Due to collation implementation specifics an Item tree could change while fixing.
The tricky thing here is to make it on a proper arena.
It's usually not a problem when a field is deterministic, however, makes a pain vice-versa, during allocation allocating.
A non-deterministic field should be refixed on each statement, since it depends on the environment state.
Changing the tree will be temporary and therefore it should be reverted after the statement execution.
For the case when the SJM scan table is the first table in the join order,
then if we want to do the sorting on the SJM scan table, then we need to
make sure that we unpack the values to base table fields in two cases:
1) Reading the SJM table and writing the sort-keys inside the sort-buffer
2) Reading the sorted data from the sort file
Fixed by:
- Make all quick_* variable allocated according to real number keys instead
of MAX_KEY
- Store all the quick* items in separated allocated structure (OPT_RANGE)
- Ensure we don't access any quick* variable without first checking
opt_range_keys.is_set(). Thanks to this, we don't need any
pre-initialization of quick* variables anymore.
Some renames was done to use the new structure:
table->quick_keys -> table->opt_range_keys
table->quick_rows[X] -> table->opt_range[X].rows
table->quick_key_parts[X] -> table->opt_range[X].key_parts
table->quick_costs[X] -> table->opt_range[X].cost
table->quick_index_only_costs[X] -> table->opt_range[X].index_only_cost
table->quick_n_ranges[X] -> table->opt_range[X].ranges
table->quick_condition_rows -> table->opt_range_condition_rows
This patch should both decrease memory needed for TABLE objects
(3528 -> 984 + keyinfo) and increase performance, thanks to less
initializations per query, and more localized memory, thanks to the
opt_range structure.
Starting from 10.3, the optimizer is able to detect that entire outer join
nests are constants (because of "Impossible ON") and remove them (see
mark_join_nest_as_const)
However, this was not properly accounted for in NESTED_JOIN structure
and the way check_interleaving_with_nj() uses its n_tables member to
check if the join prefix order is allowed.
(The result was that the optimizer could conclude that no join prefix is
allowed and fail an assertion)
reduce the amount of engine-specific code in the server,
particularly as it does not serve any purpose now.
may be needed for VP engine,
to be reconsidered in MDEV-7795
Previously multiple threads were allowed to load histograms concurrently.
There were no known problems caused by this. But given amount of data
races in this code, it'd happen sooner or later.
To avoid scalability bottleneck, histograms loading is protected by
per-TABLE_SHARE atomic variable.
Whenever histograms were loaded by preceding statement (hot-path), a
scalable load-acquire check is performed.
Whenever histograms have to be loaded anew, mutual exclusion for loaders
is established by atomic variable. If histograms are being loaded
concurrently, statement waits until load is completed.
- Table_statistics::total_hist_size moved to TABLE_STATISTICS_CB: only
meaningful within TABLE_SHARE (not used for collected stats).
- TABLE_STATISTICS_CB::histograms_can_be_read and
TABLE_STATISTICS_CB::histograms_are_read are replaced with a tri state
atomic variable.
- Simplified away alloc_histograms_for_table_share().
Note: there's still likely a data race if a thread attempts accessing
histograms data after it failed to load it (because of concurrent load).
It was there previously and goes out of the scope of this effort. One way
of fixing it could be reviving TABLE::histograms_are_read and adding
appropriate checks whenever it is needed.
Part of MDEV-19061 - table_share used for reading statistical tables is
not protected
Previously multiple threads were allowed to load statistics concurrently.
There were no known problems caused by this. But given amount of data
races in this code, it'd happen sooner or later.
To avoid scalability bottleneck, statistics loading is protected by
per-TABLE_SHARE atomic variable.
Whenever statistics were loaded by preceding statement (hot-path), a
scalable load-acquire check is performed.
Whenever statistics have to be loaded anew, mutual exclusion for loaders
is established by atomic variable. If statistics are being loaded
concurrently, statement waits until load is completed.
TABLE_STATISTICS_CB::stats_can_be_read and
TABLE_STATISTICS_CB::stats_is_read are replaced with a tri state atomic
variable.
Part of MDEV-19061 - table_share used for reading statistical tables is
not protected
MDEV-21398 Deadlock (server hang) or assertion failure in
Diagnostics_area::set_error_status upon ALTER under lock
This failure could only happen if one locked the same table
multiple times and then did an ALTER TABLE on the table.
Major change is to change all instances of
table->m_needs_reopen= true;
to
table->mark_table_for_reopen();
The main fix for the problem was to ensure that we mark all
instances of the table in the locked_table_list and when we
reopen the tables, we first close all tables before reopening
and locking them.
Other things:
- Don't call thd->locked_tables_list.reopen_tables if there
are no tables marked for reopen. (performance)
The TokuDB storage engine has been deprecated by upstream
Percona Server 8.0 in favor of MyRocks and will not be available
in subsequent major upstream releases.
Let us remove it from MariaDB Server as well.
MyRocks is actively maintained, and it can be used instead.
only MDL-prelock but do not open FK child tables for read-only (RESTRICT)
FK actions.
Tables still needs to be opened for CASCADE actions, see 9180e8666b
MDEV-22088 S3 partitioning support
All ALTER PARTITION commands should now work on S3 tables except
REBUILD PARTITION
TRUNCATE PARTITION
REORGANIZE PARTITION
In addition, PARTIONED S3 TABLES can also be replicated.
This is achived by storing the partition tables .frm and .par file on S3
for partitioned shared (S3) tables.
The discovery methods are enchanced by allowing engines that supports
discovery to also support of the partitioned tables .frm and .par file
Things in more detail
- The .frm and .par files of partitioned tables are stored in S3 and kept
in sync.
- Added hton callback create_partitioning_metadata to inform handler
that metadata for a partitoned file has changed
- Added back handler::discover_check_version() to be able to check if
a table's or a part table's definition has changed.
- Added handler::check_if_updates_are_ignored(). Needed for partitioning.
- Renamed rebind() -> rebind_psi(), as it was before.
- Changed CHF_xxx hadnler flags to an enum
- Changed some checks from using table->file->ht to use
table->file->partition_ht() to get discovery to work with partitioning.
- If TABLE_SHARE::init_from_binary_frm_image() fails, ensure that we
don't leave any .frm or .par files around.
- Fixed that writefrm() doesn't leave unusable .frm files around
- Appended extension to path for writefrm() to be able to reuse to function
for creating .par files.
- Added DBUG_PUSH("") to a a few functions that caused a lot of not
critical tracing.
