Almost all threads have gone
- the "ticking" threads, that sleep a while then do some work)
(srv_monitor_thread, srv_error_monitor_thread, srv_master_thread)
were replaced with timers. Some timers are periodic,
e.g the "master" timer.
- The btr_defragment_thread is also replaced by a timer , which
reschedules it self when current defragment "item" needs throttling
- the buf_resize_thread and buf_dump_threads are substitutes with tasks
Ditto with page cleaner workers.
- purge workers threads are not tasks as well, and purge cleaner
coordinator is a combination of a task and timer.
- All AIO is outsourced to tpool, Innodb just calls thread_pool::submit_io()
and provides the callback.
- The srv_slot_t was removed, and innodb_debug_sync used in purge
is currently not working, and needs reimplementation.
In the test innodb.instant_alter,4k we would be flagging an error
for too large row size. That error was previously only being reported
if the table was being rebuilt. Thus, this merge is fixing a small
omission in MDEV-11369 (instant ADD COLUMN).
Move row size check to early CREATE/ALTER TABLE phase. Stop checking
on table open.
dict_index_add_to_cache(): remove parameter 'strict', stop checking row size
dict_index_t::record_size_info_t: this is a result of row size check operation
create_table_info_t::row_size_is_acceptable(): performs row size check.
Issues error or warning. Writes first overflow field to InnoDB log.
create_table_info_t::create_table(): add row size check
dict_index_t::record_size_info(): this is a refactored version
of dict_index_t::rec_potentially_too_big(). New version doesn't change global
state of a program but return all interesting info. And it's callers who
decide how to handle row size overflow.
dict_index_t::rec_potentially_too_big(): removed
A conflict between MDEV-19514 (b42294bc64)
and MDEV-20934 (d7a2401750)
was resolved. We will not invoke the function ibuf_delete_recs()
from ibuf_merge_or_delete_for_page(). Instead, we will add that
logic to the function ibuf_read_merge_pages().
Due to MDEV-12288, the slow shutdown in MariaDB 10.3 will include
resetting the DB_TRX_ID for all inserted records. This might
cause the 60-second shutdown_server timeout to be exceeded.
Let us wait for the purge to complete before initiating slow shutdown.
Due to a data corruption bug that may have occurred a long time earlier
(possibly involving physical backup and MySQL Bug #69122, which was
addressed in commit f166ec71b7)
it seems possible that the InnoDB change buffer might end up containing
entries, while no buffered changes exist according to the change buffer
bitmap pages in the .ibd files.
ibuf_delete_recs(): New function, to be invoked on slow shutdown only.
Remove all buffered changes for a specific page.
ibuf_merge_or_delete_for_page(): If the change buffer bitmap is clean
and a slow shutdown is in progress, invoke ibuf_delete_recs().
We do not want to do that during normal operation, due to the additional
overhead that is involved. The bitmap page should be consistent with
the change buffer in the first place.
innobase_drop_foreign_try(): Don't evict and reload the dict_foreign_t
during instant ALTER TABLE if the FOREIGN KEY constraint is being
dropped.
The MDEV-19630 fix (commit 07b1a26c33)
was incomplete, because it did not cover a case where the
FOREIGN KEY constraint is being dropped.
mysql_insert() first opens all affected tables (which implicitly
starts a transaction in InnoDB), then stat tables.
A failure to open a stat table caused open_tables() to abort
the current stmt transaction (trans_rollback_stmt()). So, from the
server point of view the following ha_write_row()-s happened outside
of a transactions, and the server didn't bother to commit them.
The server has a mechanism to prevent a transaction being
unexpectedly committed or rolled back in the middle of a statement -
if an operation takes place _in a sub-statement_ it cannot change
the transaction state. Operations on stat tables are exactly that -
they are not allowed to change a transaction state. Put them in
a sub-statement to make sure they don't.
Apply the changes to InnoDB and XtraDB that had been
inadvertently skipped in the merge
commit ae476868a5
That merge failure sabotaged part of MDEV-20127:
>Revert a problematic auto_increment_increment 'fix' from 2014.
>This involves replacing the MDEV-8827 fix and in 10.1,
>removing some WSREP instrumentation.
The code changes were re-merged manually by executing the following:
# Get the parent of the problematic merge.
git checkout ae476868a5394041a00e75a29c7d45917e8dfae8^
# Perform the merge again.
git merge ae476868a5394041a00e75a29c7d45917e8dfae8^2
# Get the conflict resolution from that merge.
git checkout ae476868a5 .
# Note: Any changes to these files were removed (empty diff)!
git diff HEAD storage/{innobase,xtradb}/handler/ha_innodb.cc
# Apply the code changes:
git diff cf40393471b10ca68cc1d2804c22ab9203900978^2..MERGE_HEAD \
storage/{innobase,xtradb}/handler/ha_innodb.cc|
patch -p1
Historically, InnoDB split the redo log into at least 2 files.
MDEV-12061 allowed the minimum to be innodb_log_files_in_group=1,
but it kept the default at innodb_log_files_in_group=2.
Because performance seems to be slightly better with only one log file,
and because implementing an append-only variant of the log would require
a single file, let us define the default to be 1, and have
innodb_log_file_size=96M, to retain the same default total size.
We will remove the InnoDB background operation of merging buffered
changes to secondary index leaf pages. Changes will only be merged as a
result of an operation that accesses a secondary index leaf page,
such as a SQL statement that performs a lookup via that index,
or is modifying the index. Also ROLLBACK and some background operations,
such as purging the history of committed transactions, or computing
index cardinality statistics, can cause change buffer merge.
Encryption key rotation will not perform change buffer merge.
The motivation of this change is to simplify the I/O logic and to
allow crash recovery to happen in the background (MDEV-14481).
We also hope that this will reduce the number of "mystery" crashes
due to corrupted data. Because change buffer merge will typically
take place as a result of executing SQL statements, there should be
a clearer connection between the crash and the SQL statements that
were executed when the server crashed.
In many cases, a slight performance improvement was observed.
This is joint work with Thirunarayanan Balathandayuthapani
and was tested by Axel Schwenke and Matthias Leich.
The InnoDB monitor counter innodb_ibuf_merge_usec will be removed.
On slow shutdown (innodb_fast_shutdown=0), we will continue to
merge all buffered changes (and purge all undo log history).
Two InnoDB configuration parameters will be changed as follows:
innodb_disable_background_merge: Removed.
This parameter existed only in debug builds.
All change buffer merges will use synchronous reads.
innodb_force_recovery will be changed as follows:
* innodb_force_recovery=4 will be the same as innodb_force_recovery=3
(the change buffer merge cannot be disabled; it can only happen as
a result of an operation that accesses a secondary index leaf page).
The option used to be capable of corrupting secondary index leaf pages.
Now that capability is removed, and innodb_force_recovery=4 becomes 'safe'.
* innodb_force_recovery=5 (which essentially hard-wires
SET GLOBAL TRANSACTION ISOLATION LEVEL READ UNCOMMITTED)
becomes safe to use. Bogus data can be returned to SQL, but
persistent InnoDB data files will not be corrupted further.
* innodb_force_recovery=6 (ignore the redo log files)
will be the only option that can potentially cause
persistent corruption of InnoDB data files.
Code changes:
buf_page_t::ibuf_exist: New flag, to indicate whether buffered
changes exist for a buffer pool page. Pages with pending changes
can be returned by buf_page_get_gen(). Previously, the changes
were always merged inside buf_page_get_gen() if needed.
ibuf_page_exists(const buf_page_t&): Check if a buffered changes
exist for an X-latched or read-fixed page.
buf_page_get_gen(): Add the parameter allow_ibuf_merge=false.
All callers that know that they may be accessing a secondary index
leaf page must pass this parameter as allow_ibuf_merge=true,
unless it does not matter for that caller whether all buffered
changes have been applied. Assert that whenever allow_ibuf_merge
holds, the page actually is a leaf page. Attempt change buffer
merge only to secondary B-tree index leaf pages.
btr_block_get(): Add parameter 'bool merge'.
All callers of btr_block_get() should know whether the page could be
a secondary index leaf page. If it is not, we should avoid consulting
the change buffer bitmap to even consider a merge. This is the main
interface to requesting index pages from the buffer pool.
ibuf_merge_or_delete_for_page(), recv_recover_page(): Replace
buf_page_get_known_nowait() with much simpler logic, because
it is now guaranteed that that the block is x-latched or read-fixed.
mlog_init_t::mark_ibuf_exist(): Renamed from mlog_init_t::ibuf_merge().
On crash recovery, we will no longer merge any buffered changes
for the pages that we read into the buffer pool during the last batch
of applying log records.
buf_page_get_gen_known_nowait(), BUF_MAKE_YOUNG, BUF_KEEP_OLD: Remove.
btr_search_guess_on_hash(): Merge buf_page_get_gen_known_nowait()
to its only remaining caller.
buf_page_make_young_if_needed(): Define as an inline function.
Add the parameter buf_pool.
buf_page_peek_if_young(), buf_page_peek_if_too_old(): Add the
parameter buf_pool.
fil_space_validate_for_mtr_commit(): Remove a bogus comment
about background merge of the change buffer.
btr_cur_open_at_rnd_pos_func(), btr_cur_search_to_nth_level_func(),
btr_cur_open_at_index_side_func(): Use narrower data types and scopes.
ibuf_read_merge_pages(): Replaces buf_read_ibuf_merge_pages().
Merge the change buffer by invoking buf_page_get_gen().
Thanks to Eugene Kosov for noting that the fix is incomplete.
It turns out that on instant DROP/reorder column (MDEV-15562),
we must always write the metadata record, even though the table
was empty. Alternatively, we should guarantee that all undo
log records for the table have been purged. (Attempting to do
that by updating table_id leads to other problems; see
commit 1b31d8852c00b4bab6e6fe179b97db45ccb8d535.)
It would be tempting to remove dict_index_t::clear_instant_alter()
altogether, but it turns that we need that when the instant ALTER TABLE
operation of a first-time DROP COLUMN is being rolled back.
innobase_instant_try(): Clarify a comment. Purge never calls
dict_index_t::clear_instant_alter(), but it may invoke
dict_index_t::clear_instant_add(). On first-time instant DROP/reorder,
always write a metadata record, even if the table is empty.
The crash scenario is as follows:
(1) A non-empty table exists.
(2) MDEV-15562 instant ADD/DROP/reorder has been invoked.
(3) Some purgeable undo log exists for the table.
(4) The table becomes empty, containing not even any delete-marked records,
only containing the hidden metadata record that was added in (2).
(5) An instant ADD/DROP/reorder column is executed, and the table
is emptied and the (2) metadata removed.
(6) Purge processes an undo log record from (3), which will refer to
a non-existent clustered index field, because the metadata that
was created in (2) was remoeved in (5).
We fix this by adjusting step (5) so that we will never remove the
MDEV-15562-style metadata record. Removing the MDEV-11369 metadata
record (instant ADD COLUMN to the end of the table) is completely
fine at any time when the table becomes empty, because
dict_index_t::n_fields will remain unchanged.
innobase_instant_try(): Never remove the MDEV-15562 metadata record.
page_cur_delete_rec(): Do not reset FIL_PAGE_TYPE when the
MDEV-15562 metadata record is being removed as part of
btr_cur_pessimistic_update() invoked by innobase_instant_try().
Test innodb_read_only startup (which will be refused after a crash),
and test also innodb_force_recovery=5, and extract some change buffer
merge statistics. Omit any statistics about delete (purge) buffering,
because purge could happen at any time.
Use the sequence storage engine for populating the table.
memmove() should be used instead of memcpy() for overlapping memory regions.
Overlapping memory regions itself here are fine, because code simply removes
one element from arbitrary position of an array.
Files for PAGE_COMPRESSED tables that were created with
innodb_checksum_algorithm=full_crc32 store the value of
innodb_compression_algorithm at the time of the file creation.
The server-wide setting of innodb_compression_algorithm
may be changed after file creation. We must ignore any mismatch
when opening a data file, and for writes, we must use the
choice of algorithm that is stored in the file.
fil_space_t::is_flags_full_crc32_equal(): Ignore the
innodb_compression_algorithm but do compare innodb_page_size.
fil_space_t::is_flags_non_full_crc32_equal(): Ignore the
innodb_compression_algorithm.
Try to use more deterministic floating-point operations.
Apparently, 2.2 > 2.2 wrongly holds on many platforms, but
not ppc64le on the compiler used on Red Had Enterprise Linux 8.
The reason could be an infinite binary presentation:
2.2 = 0b10.001100110011…
With t1_f = 2.5 = 0b10.1, t1_f > 2.5 would no longer hold on AMD64.
Let us replace the 2.2 with 2.5 and compare t1_f >= 2.5 in order to
get more consistent results across all platforms.
