log_t::FORMAT_10_5: physical redo log format tag
log_phys_t: Buffered records in the physical format.
The log record bytes will follow the last data field,
making use of alignment padding that would otherwise be wasted.
If there are multiple records for the same page, also those
may be appended to an existing log_phys_t object if the memory
is available.
In the physical format, the first byte of a record identifies the
record and its length (up to 15 bytes). For longer records, the
immediately following bytes will encode the remaining length
in a variable-length encoding. Usually, a variable-length-encoded
page identifier will follow, followed by optional payload, whose
length is included in the initially encoded total record length.
When a mini-transaction is updating multiple fields in a page,
it can avoid repeating the tablespace identifier and page number
by setting the same_page flag (most significant bit) in the first
byte of the log record. The byte offset of the record will be
relative to where the previous record for that page ended.
Until MDEV-14425 introduces a separate file-level log for
redo log checkpoints and file operations, we will write the
file-level records in the page-level redo log file.
The record FILE_CHECKPOINT (which replaces MLOG_CHECKPOINT)
will be removed in MDEV-14425, and one sequential scan of the
page recovery log will suffice.
Compared to MLOG_FILE_CREATE2, FILE_CREATE will not include any flags.
If the information is needed, it can be parsed from WRITE records that
modify FSP_SPACE_FLAGS.
MLOG_ZIP_WRITE_STRING: Remove. The record was only introduced temporarily
as part of this work, before being replaced with WRITE (along with
MLOG_WRITE_STRING, MLOG_1BYTE, MLOG_nBYTES).
mtr_buf_t::empty(): Check if the buffer is empty.
mtr_t::m_n_log_recs: Remove. It suffices to check if m_log is empty.
mtr_t::m_last, mtr_t::m_last_offset: End of the latest m_log record,
for the same_page encoding.
page_recv_t::last_offset: Reflects mtr_t::m_last_offset.
Valid values for last_offset during recovery should be 0 or above 8.
(The first 8 bytes of a page are the checksum and the page number,
and neither are ever updated directly by log records.)
Internally, the special value 1 indicates that the same_page form
will not be allowed for the subsequent record.
mtr_t::page_create(): Take the block descriptor as parameter,
so that it can be compared to mtr_t::m_last. The INIT_INDEX_PAGE
record will always followed by a subtype byte, because same_page
records must be longer than 1 byte.
trx_undo_page_init(): Combine the writes in WRITE record.
trx_undo_header_create(): Write 4 bytes using a special MEMSET
record that includes 1 bytes of length and 2 bytes of payload.
flst_write_addr(): Define as a static function. Combine the writes.
flst_zero_both(): Replaces two flst_zero_addr() calls.
flst_init(): Do not inline the function.
fsp_free_seg_inode(): Zerofill the whole inode.
fsp_apply_init_file_page(): Initialize FIL_PAGE_PREV,FIL_PAGE_NEXT
to FIL_NULL when using the physical format.
btr_create(): Assert !page_has_siblings() because fsp_apply_init_file_page()
must have been invoked.
fil_ibd_create(): Do not write FILE_MODIFY after FILE_CREATE.
fil_names_dirty_and_write(): Remove the parameter mtr.
Write the records using a separate mini-transaction object,
because any FILE_ records must be at the start of a mini-transaction log.
recv_recover_page(): Add a fil_space_t* parameter.
After applying log to the a ROW_FORMAT=COMPRESSED page,
invoke buf_zip_decompress() to restore the uncompressed page.
buf_page_io_complete(): Remove the temporary hack to discard the
uncompressed page of a ROW_FORMAT=COMPRESSED page.
page_zip_write_header(): Remove. Use mtr_t::write() or
mtr_t::memset() instead, and update the compressed page frame
separately.
trx_undo_header_add_space_for_xid(): Remove.
trx_undo_seg_create(): Perform the changes that were previously
made by trx_undo_header_add_space_for_xid().
btr_reset_instant(): New function: Reset the table to MariaDB 10.2
or 10.3 format when rolling back an instant ALTER TABLE operation.
page_rec_find_owner_rec(): Merge with the only callers.
page_cur_insert_rec_low(): Combine writes by using a local buffer.
MEMMOVE data from the preceding record whenever feasible
(copying at least 3 bytes).
page_cur_insert_rec_zip(): Combine writes to page header fields.
PageBulk::insertPage(): Issue MEMMOVE records to copy a matching
part from the preceding record.
PageBulk::finishPage(): Combine the writes to the page header
and to the sparse page directory slots.
mtr_t::write(): Only log the least significant (last) bytes
of multi-byte fields that actually differ.
For updating FSP_SIZE, we must always write all 4 bytes to the
redo log, so that the fil_space_set_recv_size() logic in
recv_sys_t::parse() will work.
mtr_t::memcpy(), mtr_t::zmemcpy(): Take a pointer argument
instead of a numeric offset to the page frame. Only log the
last bytes of multi-byte fields that actually differ.
In fil_space_crypt_t::write_page0(), we must log also any
unchanged bytes, so that recovery will recognize the record
and invoke fil_crypt_parse().
Future work:
MDEV-21724 Optimize page_cur_insert_rec_low() redo logging
MDEV-21725 Optimize btr_page_reorganize_low() redo logging
MDEV-21727 Optimize redo logging for ROW_FORMAT=COMPRESSED
mtr_t::log_write_low(): Replaces mlog_write_initial_log_record_low().
mtr_t::log_file_op(): Replaces fil_op_write_log().
mtr_t::free(): Write MLOG_INIT_FREE_PAGE.
mtr_t::init(): Write MLOG_INIT_FILE_PAGE2.
mtr_t::page_create(): Write record about the partial initialization
of an index page.
mlog_catenate_ulint(), mlog_catenate_string(),
mlog_open(), mlog_close(): Remove.
No longer write the following redo log records:
MLOG_COMP_LIST_END_DELETE, MLOG_LIST_END_DELETE,
MLOG_COMP_LIST_START_DELETE, MLOG_LIST_START_DELETE,
MLOG_REC_DELETE,MLOG_COMP_REC_DELETE.
Each individual deleted record will be logged separately
using physical log records.
page_dir_slot_set_n_owned(),
page_zip_rec_set_owned(), page_zip_dir_delete(), page_zip_clear_rec():
Add the parameter mtr, and write redo log.
page_dir_slot_set_rec(): Remove. Replaced with lower-level operations
that write redo log when necessary.
page_rec_set_n_owned(): Replaces rec_set_n_owned_old(),
rec_set_n_owned_new().
rec_set_heap_no(): Replaces rec_set_heap_no_old(), rec_set_heap_no_new().
page_mem_free(), page_dir_split_slot(), page_dir_balance_slot():
Add the parameter mtr.
page_dir_set_n_slots(): Merge with the caller page_dir_split_slot().
page_dir_slot_set_rec(): Merge with the callers page_dir_split_slot()
and page_dir_balance_slot().
page_cur_insert_rec_low(), page_cur_insert_rec_zip():
Suppress the logging of lower-level operations.
page_cur_delete_rec_write_log(): Remove.
page_cur_delete_rec(): Do not tolerate mtr=NULL.
rec_convert_dtuple_to_rec_old(), rec_convert_dtuple_to_rec_comp():
Replace rec_set_heap_no_old() and rec_set_heap_no_new() with direct
access that does not involve redo logging.
mtr_t::memcpy(): Do allow non-redo-logged writes to uncompressed pages
of ROW_FORMAT=COMPRESSED pages.
buf_page_io_complete(): Evict the uncompressed page of
a ROW_FORMAT=COMPRESSED page after recovery. Because we no longer
write logical log records for deleting index records, but instead
write physical records that may refer directly to the compressed
page frame of a ROW_FORMAT=COMPRESSED page, and because on recovery
we will only apply the changes to the ROW_FORMAT=COMPRESSED page,
the uncompressed page frame can be stale until page_zip_decompress()
is executed.
recv_parse_or_apply_log_rec_body(): After applying MLOG_ZIP_WRITE_STRING,
ensure that the FIL_PAGE_TYPE of the uncompressed page matches the
compressed page, because buf_flush_init_for_writing() assumes that
field to be valid.
mlog_init_t::mark_ibuf_exist(): Invoke page_zip_decompress(), because
the uncompressed page after buf_page_create() is not necessarily
up to date.
buf_LRU_block_remove_hashed(): Bypass a page_zip_validate() check
during redo log apply.
recv_apply_hashed_log_recs(): Invoke mlog_init.mark_ibuf_exist()
also for the last batch, to ensure that page_zip_decompress() will
be called for freshly initialized pages.
Our benchmarking efforts indicate that the reasons for splitting the
buf_pool in commit c18084f71b
have mostly gone away, possibly as a result of
mysql/mysql-server@ce6109ebfd
or similar work.
Only in one write-heavy benchmark where the working set size is
ten times the buffer pool size, the buf_pool->mutex would be
less contended with 4 buffer pool instances than with 1 instance,
in buf_page_io_complete(). That contention could be alleviated
further by making more use of std::atomic and by splitting
buf_pool_t::mutex further (MDEV-15053).
We will deprecate and ignore the following parameters:
innodb_buffer_pool_instances
innodb_page_cleaners
There will be only one buffer pool and one page cleaner task.
In a number of INFORMATION_SCHEMA views, columns that indicated
the buffer pool instance will be removed:
information_schema.innodb_buffer_page.pool_id
information_schema.innodb_buffer_page_lru.pool_id
information_schema.innodb_buffer_pool_stats.pool_id
information_schema.innodb_cmpmem.buffer_pool_instance
information_schema.innodb_cmpmem_reset.buffer_pool_instance
During native table rebuild or index creation, InnoDB used to skip
redo logging and write MLOG_INDEX_LOAD records to inform crash recovery
and Mariabackup of the gaps in redo log. This is fragile and prohibits
some optimizations, such as skipping the doublewrite buffer for
newly (re)initialized pages (MDEV-19738).
row_merge_write_redo(): Remove. We do not write MLOG_INDEX_LOAD
records any more. Instead, we write full redo log.
FlushObserver: Remove.
fseg_free_page_func(): Remove the parameter log. Redo logging
cannot be disabled.
fil_space_t::redo_skipped_count: Remove.
We cannot remove buf_block_t::skip_flush_check, because PageBulk
will temporarily generate invalid B-tree pages in the buffer pool.
Let us define page_id_t as a thin wrapper of uint64_t so that
the comparison operators can be simplified. This is a follow-up
to the original commit 14be814380.
The comparison operator for recv_sys.pages.emplace() turned out to be
a busy spot in a recovery benchmark. That data structure was introduced
in MDEV-19586 in commit 177a571e01.
InnoDB crash recovery used a special type of mem_heap_t that
allocates backing store from the buffer pool. That incurred
a significant overhead, leading to underutilization of memory,
and limiting the maximum contiguous allocated size of a log record.
recv_sys_t::blocks: A linked list of buf_block_t that are allocated
by buf_block_alloc() for redo log records. Replaces recv_sys_t::heap.
We repurpose buf_block_t::unzip_LRU for linking the elements.
recv_sys_t::max_log_blocks: Renamed from recv_n_pool_free_frames.
recv_sys_t::max_blocks(): Accessor for max_log_blocks.
recv_sys_t::alloc(): Allocate memory from the current recv_sys_t::blocks
element, or allocate another block. In debug builds, various free()
member functions must be invoked, because we repurpose
buf_page_t::buf_fix_count for tracking allocations.
recv_sys_t::free_corrupted_page(): Renamed from recv_recover_corrupt_page()
recv_sys_t::is_memory_exhausted(): Renamed from recv_sys_heap_check()
recv_sys_t::pages and its elements are allocated directly by the
system memory allocator.
recv_parse_log_recs(): Remove the parameter available_memory.
We rename some variables 'store_to_hash' to 'store', because
recv_sys.pages is not actually a hash table.
This is joint work with Thirunarayanan Balathandayuthapani.
Before commit 90c52e5291 introduced
aligned_malloc(), InnoDB always used a pattern of over-allocating
memory and invoking ut_align() to guarantee the desired alignment.
It is cleaner to invoke aligned_malloc() and aligned_free() directly.
ut_align(): Remove. In assertions, ut_align_down() can be used instead.
Introduce memcpy_aligned<N>(), memcmp_aligned<N>(), memset_aligned<N>()
and use them for accessing InnoDB page header fields that are known
to be aligned.
MY_ASSUME_ALIGNED(): Wrapper for the GCC/clang __builtin_assume_aligned().
Nothing similar seems to exist in Microsoft Visual Studio, and the
C++20 std::assume_aligned is not available to us yet.
Explicitly specified alignment guarantees allow compilers to generate
faster code on platforms with strict alignment rules, instead of
emitting calls to potentially unaligned memcpy(), memcmp(), or memset().
At each mini-transaction commit, the log sequence number of the
mini-transaction must be written to each modified page, so that
it will be available in the FIL_PAGE_LSN field when the page is
being read in crash recovery.
InnoDB was unnecessarily allocating redundant storage for the
field, in buf_page_t::newest_modification. Let us access
FIL_PAGE_LSN directly.
Furthermore, on ALTER TABLE...IMPORT TABLESPACE, let us write
0 to FIL_PAGE_LSN instead of using log_sys.lsn.
buf_flush_init_for_writing(), buf_flush_update_zip_checksum(),
fil_encrypt_buf_for_full_crc32(), fil_encrypt_buf(),
fil_space_encrypt(): Remove the parameter lsn.
buf_page_get_newest_modification(): Merge with the only caller.
buf_tmp_reserve_compression_buf(), buf_tmp_page_encrypt(),
buf_page_encrypt(): Define static in the same compilation unit
with the only caller.
PageConverter::m_current_lsn: Remove. Write 0 to FIL_PAGE_LSN
on ALTER TABLE...IMPORT TABLESPACE.
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.
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().
When MDEV-12026 introduced innodb_checksum_algorithm=full_crc32 in
MariaDB 10.4, it accidentally added a dependency on buf_page_t::encrypted.
Now that the flag has been removed, we must adjust the page-read routine.
buf_page_io_complete(): When the full_crc32 page checksum matches but the
tablespace ID in the page does not match after decrypting, we should
declare it a decryption failure and suppress the page dump output and
any attempts to re-read the page.
In MariaDB 10.4.0, commit 09af00cbde
removed the crash-upgrade logic for the MariaDB 10.2
innodb_safe_truncate=OFF TRUNCATE TABLE (which was the only option
between MariaDB 10.2.2 and 10.2.18), but failed to adjust some
comments and code.
buf_page_io_complete(): Remove a bogus comment about TRUNCATE.
dict_recreate_index_tree(): Unused function; remove.
fil_space_t::stop_new_ops: Clarify the comment.
fil_space_acquire_low(): Remove a bogus comment about TRUNCATE.
fil_check_pending_ops(), fil_check_pending_io(): Adjust a warning message.
This code is only invoked as part of DISCARD TABLESPACE or DROP TABLE.
DROP TABLE is internally used as part of ALTER TABLE, OPTIMIZE TABLE,
or TRUNCATE TABLE.
RemoteDatafile::create_link_file(): Clarify a comment.
ibuf_delete_for_discarded_space(): Clarify the function comment.
dict_table_x_lock_indexes(), dict_table_x_unlock_indexes():
Merge with the only remaining caller, row_quiesce_set_state().
page_create_zip(): Remove a bogus comment about TRUNCATE.
Datafile::find_space_id(): Fix a regression that was introduced
in c0f47a4a58 for MDEV-12026.
Because the function buf_page_is_corrupted() now determines
the physical page size from the fsp_flags, our buffer size must
agree with the fsp_flags.
buf_page_is_corrupted(): Use the correct accessor
fil_space_t::zip_size() for convering the tablespace flags.
ROW_FORMAT=COMPRESSED files never use innodb_checksum_algorithm=full_crc32.
Problem:
========
Checksum for the encrypted temporary tablespace is not stored in the page
for full crc32 format.
Solution:
========
Made temporary tablespace in full crc32 format irrespective of encryption
parameter.
buf_tmp_page_encrypt(), buf_tmp_page_decrypt() - Both follows full_crc32
format.
Problem:
=======
Checksum fields can have value as zero. In that case, InnoDB falsely
consider that page should be all zeroes. It leads to wrong detection of page
corruption.
Solution:
========
Remove the condition that checks if checksum fields are zero then
page should be all zeroes.
Shorten some VARCHAR attributes to a more reasonable length.
INNODB_METRICS: Rename the column STATUS to ENABLED, and make it Boolean.
Replace with INT(1) many Boolean attributes that were declared as VARCHAR
containing 'NO','YES','disabled','enabled','Uninitialized','Initialized'.
Replace some VARCHAR attributes with ENUM.
Replace some BIGINT with INT when 32 bits are sufficient.
Remove INNODB_SYS_TABLESPACES.SPACE_TYPE. The type of a tablespace
can be derived from the tablespace ID. A fixed number is used for
the system tablespace and the temporary tablespace. All other tablespaces
are single-table or single-partition tablespaces.
i_s_locks_row_t::lock_type, lock_get_type_str(): Remove.
This is a redundant field. Table and record locks can be
distinguished by whether i_s_locks_row_t::lock_index is NULL.
fill_trx_row(): Do not unnecessarily copy the constant strings that
trx->op_info is pointing to.
i_s_locks_row_t::lock_mode: Replace string with integer.
lock_get_mode_str(), lock_get_trx_id(), lock_get_trx(): Remove.
field_store_ulint(): Remove.
