This will allow us to reduce critical section protected by
trx_sys.mutex:
- no need to maintain global m_free list
- eliminate if (trx->read_view == NULL) condition.
On x86_64 sizeof(Readview) is 144 mostly due to padding, sizeof(trx_t)
with ReadView is 1200.
Also don't close ReadView for read-write transactions, just mark it
closed similarly to read-only.
Clean-up: removed n_prepared_recovered_trx and n_prepared_trx, which
accidentally re-appeared after some rebase.
MDEV-14511 tried to avoid some consistency problems related to InnoDB
persistent statistics. The persistent statistics are being written by
an InnoDB internal SQL interpreter that requires the InnoDB data dictionary
cache to be locked.
Before MDEV-14511, the statistics were written during DDL in separate
transactions, which could unnecessarily reduce performance (each commit
would require a redo log flush) and break atomicity, because the statistics
would be updated separately from the dictionary transaction.
However, because it is unacceptable to hold the InnoDB data dictionary
cache locked while suspending the execution for waiting for a
transactional lock (in the mysql.innodb_index_stats or
mysql.innodb_table_stats tables) to be released, any lock conflict
was immediately be reported as "lock wait timeout".
To fix MDEV-14941, an attempt to reduce these lock conflicts by acquiring
transactional locks on the user tables in both the statistics and DDL
operations was made, but it would still not entirely prevent lock conflicts
on the mysql.innodb_index_stats and mysql.innodb_table_stats tables.
Fixing the remaining problems would require a change that is too intrusive
for a GA release series, such as MariaDB 10.2.
Thefefore, we revert the change MDEV-14511. To silence the
MDEV-13201 assertion, we use the pre-existing flag trx_t::internal.
trx->read_view|= 1 was done in a silly attempt to fix race condition
where trx->read_view was closed without trx_sys.mutex lock by read-only
trasnactions.
This just made the problem less likely to happen. In fact there was race
condition in const version of trx_get_read_view(): pointer may change to
garbage any moment after MVCC::is_view_active(trx->read_view) check and
before this function returns.
This patch doesn't fix this race condition, but rather makes it's
consequences less destructive.
There is only one transaction system object in InnoDB.
Allocate the storage for it at link time, not at runtime.
lock_rec_fetch_page(): Use the correct fetch mode BUF_GET.
Pages may never be deallocated from a tablespace while
record locks are pointing to them.
Let lock_print_info_all_transactions() iterate rw_trx_hash instead of
rw_trx_list.
When printing info of locks for transactions, InnoDB monitor doesn't
attempt to read relevant page from disk anymore. The code was prone
to race conditions.
Note that TrxListIterator didn't work as advertised: it iterated
rw_trx_list only.
Reduce divergence between trx_sys_t::rw_trx_hash and trx_sys_t::rw_trx_list
by not adding recovered COMMITTED transactions to trx_sys_t::rw_trx_list.
Such transactions are discarded immediately without creating trx object.
This also required to split rollback and cleanup phases of recovery. To
reflect these updates the following renames happened:
trx_rollback_or_clean_all_recovered() -> trx_rollback_all_recovered()
trx_rollback_or_clean_is_active -> trx_rollback_is_active
trx_rollback_or_clean_recovered() -> trx_rollback_recovered()
trx_cleanup_at_db_startup() -> trx_cleanup_recovered()
Also removed a hack from lock_trx_release_locks(). Instead let recovery
rollback thread to skip committed XA transactions.
trx reference counter was updated under mutex and read without any
protection. This is both slow and unsafe. Use atomic operations for
reference counter accesses.
trx_sys_t::rw_trx_set is implemented as std::set, which does a few quite
expensive operations under trx_sys_t::mutex protection: e.g. malloc/free
when adding/removing elements. Traversing b-tree is not that cheap either.
This has negative scalability impact, which is especially visible when running
oltp_update_index.lua benchmark on a ramdisk.
To reduce trx_sys_t::mutex contention std::set is replaced with LF_HASH. None
of LF_HASH operations require trx_sys_t::mutex (nor any other global mutex)
protection.
Another interesting issue observed with std::set is reproducible ~2% performance
decline after benchmark is ran for ~60 seconds. With LF_HASH results are stable.
All in all this patch optimises away one of three trx_sys->mutex locks per
oltp_update_index.lua query. The other two critical sections became smaller.
Relevant clean-ups:
Replaced rw_trx_set iteration at startup with local set. The latter is needed
because values inserted to rw_trx_list must be ordered by trx->id.
Removed redundant conditions from trx_reference(): it is (and even was) never
called with transactions that have trx->state == TRX_STATE_COMMITTED_IN_MEMORY.
do_ref_count doesn't (and probably even didn't) make any sense: now it is called
only when reference counter increment is actually requested.
Moved condition out of mutex in trx_erase_lists().
trx_rw_is_active(), trx_rw_is_active_low() and trx_get_rw_trx_by_id() were
greatly simplified and replaced by appropriate trx_rw_hash_t methods.
Compared to rw_trx_set, rw_trx_hash holds transactions only in PREPARED or
ACTIVE states. Transactions in COMMITTED state were required to be found
at InnoDB startup only. They are now looked up in the local set.
Removed unused trx_assert_recovered().
Removed unused innobase_get_trx() declaration.
Removed rather semantically incorrect trx_sys_rw_trx_add().
Moved information printout from trx_sys_init_at_db_start() to
trx_lists_init_at_db_start().
Introduce the debug flag trx_t::persistent_stats to suppress the
assertion for the updates of persistent statistics during fast
shutdown.
dict_stats_exec_sql(): Do execute the statement even though shutdown
has been initiated.
THD::vers_update_trt, trx_t::vers_update_trt, trx_savept_t::vers_update_trt:
Remove. Instead, determine from trx_t::mod_tables whether versioned
columns were affected by the transaction.
handlerton::prepare_commit_versioned: Replaces vers_get_trt_data.
Return the transaction start ID and also the commit ID, in case
the transaction modified any system-versioned columns (0 if not).
TR_table::store_data(): Remove (merge with update() below).
TR_table::update(): Add the parameters start_id, end_id.
ha_commit_trans(): Remove a condition on SQLCOM_ALTER_TABLE.
If we need something special for ALTER TABLE...ALGORITHM=INPLACE,
that can be done inside InnoDB by modifying trx_t::mod_tables.
innodb_prepare_commit_versioned(): Renamed from innodb_get_trt_data().
Check trx_t::mod_tables to see if any changes to versioned columns
are present.
trx_mod_table_time_t: A pair of logical timestamps, replacing the
undo_no_t in trx_mod_tables_t. Keep track of not only the first
modification to a persistent table in each transaction, but also
the first modification of a versioned column in a table.
dtype_t, dict_col_t: Add the accessor is_any_versioned(), to check
if the type refers to a system-versioned user or system column.
upd_t::affects_versioned(): Check if an update affects a versioned
column.
trx_undo_report_row_operation(): If a versioned column is affected
by the update, invoke trx_mod_table_time_t::set_versioned().
trx_rollback_to_savepoint_low(): If all changes to versioned columns
were rolled back, invoke trx_mod_table_time_t::rollback_versioned(),
so that trx_mod_table_time_t::is_versioned() will no longer hold.
The non-persistent UPDATE_TIME for InnoDB tables was not being
updated consistently at transaction commit.
If a transaction is partly rolled back so that in the end it will
not modify a table that it intended to modify, the update_time will
be updated nevertheless. This will also happen when InnoDB fails
to write an undo log record for the intended modification.
If a transaction is committed internally in InnoDB, instead of
being committed from the SQL interface, then the trx_t::mod_tables
will not be applied to the update_time of the tables.
trx_t::mod_tables: Replace the std::set<dict_table_t*>
with std::map<dict_table_t*,undo_no_t>, so that the very first
modification within the transaction is identified.
trx_undo_report_row_operation(): Update mod_tables for every operation
after the undo log record was successfully written.
trx_rollback_to_savepoint_low(): After partial rollback, erase from
trx_t::mod_tables any tables for which all changes were rolled back.
trx_commit_in_memory(): Tighten some assertions and simplify conditions.
Invoke trx_update_mod_tables_timestamp() if persistent tables were
affected.
trx_commit_for_mysql(): Remove the call to
trx_update_mod_tables_timestamp(), as it is now invoked at the
lower level, in trx_commit_in_memory().
trx_rollback_finish(): Clear mod_tables before invoking trx_commit(),
because the trx_commit_in_memory() would otherwise wrongly process
mod_tables after a full ROLLBACK.
For InnoDB tables, adding, dropping and reordering columns has
required a rebuild of the table and all its indexes. Since MySQL 5.6
(and MariaDB 10.0) this has been supported online (LOCK=NONE), allowing
concurrent modification of the tables.
This work revises the InnoDB ROW_FORMAT=REDUNDANT, ROW_FORMAT=COMPACT
and ROW_FORMAT=DYNAMIC so that columns can be appended instantaneously,
with only minor changes performed to the table structure. The counter
innodb_instant_alter_column in INFORMATION_SCHEMA.GLOBAL_STATUS
is incremented whenever a table rebuild operation is converted into
an instant ADD COLUMN operation.
ROW_FORMAT=COMPRESSED tables will not support instant ADD COLUMN.
Some usability limitations will be addressed in subsequent work:
MDEV-13134 Introduce ALTER TABLE attributes ALGORITHM=NOCOPY
and ALGORITHM=INSTANT
MDEV-14016 Allow instant ADD COLUMN, ADD INDEX, LOCK=NONE
The format of the clustered index (PRIMARY KEY) is changed as follows:
(1) The FIL_PAGE_TYPE of the root page will be FIL_PAGE_TYPE_INSTANT,
and a new field PAGE_INSTANT will contain the original number of fields
in the clustered index ('core' fields).
If instant ADD COLUMN has not been used or the table becomes empty,
or the very first instant ADD COLUMN operation is rolled back,
the fields PAGE_INSTANT and FIL_PAGE_TYPE will be reset
to 0 and FIL_PAGE_INDEX.
(2) A special 'default row' record is inserted into the leftmost leaf,
between the page infimum and the first user record. This record is
distinguished by the REC_INFO_MIN_REC_FLAG, and it is otherwise in the
same format as records that contain values for the instantly added
columns. This 'default row' always has the same number of fields as
the clustered index according to the table definition. The values of
'core' fields are to be ignored. For other fields, the 'default row'
will contain the default values as they were during the ALTER TABLE
statement. (If the column default values are changed later, those
values will only be stored in the .frm file. The 'default row' will
contain the original evaluated values, which must be the same for
every row.) The 'default row' must be completely hidden from
higher-level access routines. Assertions have been added to ensure
that no 'default row' is ever present in the adaptive hash index
or in locked records. The 'default row' is never delete-marked.
(3) In clustered index leaf page records, the number of fields must
reside between the number of 'core' fields (dict_index_t::n_core_fields
introduced in this work) and dict_index_t::n_fields. If the number
of fields is less than dict_index_t::n_fields, the missing fields
are replaced with the column value of the 'default row'.
Note: The number of fields in the record may shrink if some of the
last instantly added columns are updated to the value that is
in the 'default row'. The function btr_cur_trim() implements this
'compression' on update and rollback; dtuple::trim() implements it
on insert.
(4) In ROW_FORMAT=COMPACT and ROW_FORMAT=DYNAMIC records, the new
status value REC_STATUS_COLUMNS_ADDED will indicate the presence of
a new record header that will encode n_fields-n_core_fields-1 in
1 or 2 bytes. (In ROW_FORMAT=REDUNDANT records, the record header
always explicitly encodes the number of fields.)
We introduce the undo log record type TRX_UNDO_INSERT_DEFAULT for
covering the insert of the 'default row' record when instant ADD COLUMN
is used for the first time. Subsequent instant ADD COLUMN can use
TRX_UNDO_UPD_EXIST_REC.
This is joint work with Vin Chen (陈福荣) from Tencent. The design
that was discussed in April 2017 would not have allowed import or
export of data files, because instead of the 'default row' it would
have introduced a data dictionary table. The test
rpl.rpl_alter_instant is exactly as contributed in pull request #408.
The test innodb.instant_alter is based on a contributed test.
The redo log record format changes for ROW_FORMAT=DYNAMIC and
ROW_FORMAT=COMPACT are as contributed. (With this change present,
crash recovery from MariaDB 10.3.1 will fail in spectacular ways!)
Also the semantics of higher-level redo log records that modify the
PAGE_INSTANT field is changed. The redo log format version identifier
was already changed to LOG_HEADER_FORMAT_CURRENT=103 in MariaDB 10.3.1.
Everything else has been rewritten by me. Thanks to Elena Stepanova,
the code has been tested extensively.
When rolling back an instant ADD COLUMN operation, we must empty the
PAGE_FREE list after deleting or shortening the 'default row' record,
by calling either btr_page_empty() or btr_page_reorganize(). We must
know the size of each entry in the PAGE_FREE list. If rollback left a
freed copy of the 'default row' in the PAGE_FREE list, we would be
unable to determine its size (if it is in ROW_FORMAT=COMPACT or
ROW_FORMAT=DYNAMIC) because it would contain more fields than the
rolled-back definition of the clustered index.
UNIV_SQL_DEFAULT: A new special constant that designates an instantly
added column that is not present in the clustered index record.
len_is_stored(): Check if a length is an actual length. There are
two magic length values: UNIV_SQL_DEFAULT, UNIV_SQL_NULL.
dict_col_t::def_val: The 'default row' value of the column. If the
column is not added instantly, def_val.len will be UNIV_SQL_DEFAULT.
dict_col_t: Add the accessors is_virtual(), is_nullable(), is_instant(),
instant_value().
dict_col_t::remove_instant(): Remove the 'instant ADD' status of
a column.
dict_col_t::name(const dict_table_t& table): Replaces
dict_table_get_col_name().
dict_index_t::n_core_fields: The original number of fields.
For secondary indexes and if instant ADD COLUMN has not been used,
this will be equal to dict_index_t::n_fields.
dict_index_t::n_core_null_bytes: Number of bytes needed to
represent the null flags; usually equal to UT_BITS_IN_BYTES(n_nullable).
dict_index_t::NO_CORE_NULL_BYTES: Magic value signalling that
n_core_null_bytes was not initialized yet from the clustered index
root page.
dict_index_t: Add the accessors is_instant(), is_clust(),
get_n_nullable(), instant_field_value().
dict_index_t::instant_add_field(): Adjust clustered index metadata
for instant ADD COLUMN.
dict_index_t::remove_instant(): Remove the 'instant ADD' status
of a clustered index when the table becomes empty, or the very first
instant ADD COLUMN operation is rolled back.
dict_table_t: Add the accessors is_instant(), is_temporary(),
supports_instant().
dict_table_t::instant_add_column(): Adjust metadata for
instant ADD COLUMN.
dict_table_t::rollback_instant(): Adjust metadata on the rollback
of instant ADD COLUMN.
prepare_inplace_alter_table_dict(): First create the ctx->new_table,
and only then decide if the table really needs to be rebuilt.
We must split the creation of table or index metadata from the
creation of the dictionary table records and the creation of
the data. In this way, we can transform a table-rebuilding operation
into an instant ADD COLUMN operation. Dictionary objects will only
be added to cache when table rebuilding or index creation is needed.
The ctx->instant_table will never be added to cache.
dict_table_t::add_to_cache(): Modified and renamed from
dict_table_add_to_cache(). Do not modify the table metadata.
Let the callers invoke dict_table_add_system_columns() and if needed,
set can_be_evicted.
dict_create_sys_tables_tuple(), dict_create_table_step(): Omit the
system columns (which will now exist in the dict_table_t object
already at this point).
dict_create_table_step(): Expect the callers to invoke
dict_table_add_system_columns().
pars_create_table(): Before creating the table creation execution
graph, invoke dict_table_add_system_columns().
row_create_table_for_mysql(): Expect all callers to invoke
dict_table_add_system_columns().
create_index_dict(): Replaces row_merge_create_index_graph().
innodb_update_n_cols(): Renamed from innobase_update_n_virtual().
Call my_error() if an error occurs.
btr_cur_instant_init(), btr_cur_instant_init_low(),
btr_cur_instant_root_init():
Load additional metadata from the clustered index and set
dict_index_t::n_core_null_bytes. This is invoked
when table metadata is first loaded into the data dictionary.
dict_boot(): Initialize n_core_null_bytes for the four hard-coded
dictionary tables.
dict_create_index_step(): Initialize n_core_null_bytes. This is
executed as part of CREATE TABLE.
dict_index_build_internal_clust(): Initialize n_core_null_bytes to
NO_CORE_NULL_BYTES if table->supports_instant().
row_create_index_for_mysql(): Initialize n_core_null_bytes for
CREATE TEMPORARY TABLE.
commit_cache_norebuild(): Call the code to rename or enlarge columns
in the cache only if instant ADD COLUMN is not being used.
(Instant ADD COLUMN would copy all column metadata from
instant_table to old_table, including the names and lengths.)
PAGE_INSTANT: A new 13-bit field for storing dict_index_t::n_core_fields.
This is repurposing the 16-bit field PAGE_DIRECTION, of which only the
least significant 3 bits were used. The original byte containing
PAGE_DIRECTION will be accessible via the new constant PAGE_DIRECTION_B.
page_get_instant(), page_set_instant(): Accessors for the PAGE_INSTANT.
page_ptr_get_direction(), page_get_direction(),
page_ptr_set_direction(): Accessors for PAGE_DIRECTION.
page_direction_reset(): Reset PAGE_DIRECTION, PAGE_N_DIRECTION.
page_direction_increment(): Increment PAGE_N_DIRECTION
and set PAGE_DIRECTION.
rec_get_offsets(): Use the 'leaf' parameter for non-debug purposes,
and assume that heap_no is always set.
Initialize all dict_index_t::n_fields for ROW_FORMAT=REDUNDANT records,
even if the record contains fewer fields.
rec_offs_make_valid(): Add the parameter 'leaf'.
rec_copy_prefix_to_dtuple(): Assert that the tuple is only built
on the core fields. Instant ADD COLUMN only applies to the
clustered index, and we should never build a search key that has
more than the PRIMARY KEY and possibly DB_TRX_ID,DB_ROLL_PTR.
All these columns are always present.
dict_index_build_data_tuple(): Remove assertions that would be
duplicated in rec_copy_prefix_to_dtuple().
rec_init_offsets(): Support ROW_FORMAT=REDUNDANT records whose
number of fields is between n_core_fields and n_fields.
cmp_rec_rec_with_match(): Implement the comparison between two
MIN_REC_FLAG records.
trx_t::in_rollback: Make the field available in non-debug builds.
trx_start_for_ddl_low(): Remove dangerous error-tolerance.
A dictionary transaction must be flagged as such before it has generated
any undo log records. This is because trx_undo_assign_undo() will mark
the transaction as a dictionary transaction in the undo log header
right before the very first undo log record is being written.
btr_index_rec_validate(): Account for instant ADD COLUMN
row_undo_ins_remove_clust_rec(): On the rollback of an insert into
SYS_COLUMNS, revert instant ADD COLUMN in the cache by removing the
last column from the table and the clustered index.
row_search_on_row_ref(), row_undo_mod_parse_undo_rec(), row_undo_mod(),
trx_undo_update_rec_get_update(): Handle the 'default row'
as a special case.
dtuple_t::trim(index): Omit a redundant suffix of an index tuple right
before insert or update. After instant ADD COLUMN, if the last fields
of a clustered index tuple match the 'default row', there is no
need to store them. While trimming the entry, we must hold a page latch,
so that the table cannot be emptied and the 'default row' be deleted.
btr_cur_optimistic_update(), btr_cur_pessimistic_update(),
row_upd_clust_rec_by_insert(), row_ins_clust_index_entry_low():
Invoke dtuple_t::trim() if needed.
row_ins_clust_index_entry(): Restore dtuple_t::n_fields after calling
row_ins_clust_index_entry_low().
rec_get_converted_size(), rec_get_converted_size_comp(): Allow the number
of fields to be between n_core_fields and n_fields. Do not support
infimum,supremum. They are never supposed to be stored in dtuple_t,
because page creation nowadays uses a lower-level method for initializing
them.
rec_convert_dtuple_to_rec_comp(): Assign the status bits based on the
number of fields.
btr_cur_trim(): In an update, trim the index entry as needed. For the
'default row', handle rollback specially. For user records, omit
fields that match the 'default row'.
btr_cur_optimistic_delete_func(), btr_cur_pessimistic_delete():
Skip locking and adaptive hash index for the 'default row'.
row_log_table_apply_convert_mrec(): Replace 'default row' values if needed.
In the temporary file that is applied by row_log_table_apply(),
we must identify whether the records contain the extra header for
instantly added columns. For now, we will allocate an additional byte
for this for ROW_T_INSERT and ROW_T_UPDATE records when the source table
has been subject to instant ADD COLUMN. The ROW_T_DELETE records are
fine, as they will be converted and will only contain 'core' columns
(PRIMARY KEY and some system columns) that are converted from dtuple_t.
rec_get_converted_size_temp(), rec_init_offsets_temp(),
rec_convert_dtuple_to_temp(): Add the parameter 'status'.
REC_INFO_DEFAULT_ROW = REC_INFO_MIN_REC_FLAG | REC_STATUS_COLUMNS_ADDED:
An info_bits constant for distinguishing the 'default row' record.
rec_comp_status_t: An enum of the status bit values.
rec_leaf_format: An enum that replaces the bool parameter of
rec_init_offsets_comp_ordinary().
Let InnoDB purge reset DB_TRX_ID,DB_ROLL_PTR when the history is removed.
[TODO: It appears that the resetting is not taking place as often as
it could be. We should test that a simple INSERT should eventually
cause row_purge_reset_trx_id() to be invoked unless DROP TABLE is
invoked soon enough.]
The InnoDB clustered index record system columns DB_TRX_ID,DB_ROLL_PTR
are used by multi-versioning. After the history is no longer needed, these
columns can safely be reset to 0 and 1<<55 (to indicate a fresh insert).
When a reader sees 0 in the DB_TRX_ID column, it can instantly determine
that the record is present the read view. There is no need to acquire
the transaction system mutex to check if the transaction exists, because
writes can never be conducted by a transaction whose ID is 0.
The persistent InnoDB undo log used to be split into two parts:
insert_undo and update_undo. The insert_undo log was discarded at
transaction commit or rollback, and the update_undo log was processed
by the purge subsystem. As part of this change, we will only generate
a single undo log for new transactions, and the purge subsystem will
reset the DB_TRX_ID whenever a clustered index record is touched.
That is, all persistent undo log will be preserved at transaction commit
or rollback, to be removed by purge.
The InnoDB redo log format is changed in two ways:
We remove the redo log record type MLOG_UNDO_HDR_REUSE, and
we introduce the MLOG_ZIP_WRITE_TRX_ID record for updating the
DB_TRX_ID,DB_ROLL_PTR in a ROW_FORMAT=COMPRESSED table.
This is also changing the format of persistent InnoDB data files:
undo log and clustered index leaf page records. It will still be
possible via import and export to exchange data files with earlier
versions of MariaDB. The change to clustered index leaf page records
is simple: we allow DB_TRX_ID to be 0.
When it comes to the undo log, we must be able to upgrade from earlier
MariaDB versions after a clean shutdown (no redo log to apply).
While it would be nice to perform a slow shutdown (innodb_fast_shutdown=0)
before an upgrade, to empty the undo logs, we cannot assume that this
has been done. So, separate insert_undo log may exist for recovered
uncommitted transactions. These transactions may be automatically
rolled back, or they may be in XA PREPARE state, in which case InnoDB
will preserve the transaction until an explicit XA COMMIT or XA ROLLBACK.
Upgrade has been tested by starting up MariaDB 10.2 with
./mysql-test-run --manual-gdb innodb.read_only_recovery
and then starting up this patched server with
and without --innodb-read-only.
trx_undo_ptr_t::undo: Renamed from update_undo.
trx_undo_ptr_t::old_insert: Renamed from insert_undo.
trx_rseg_t::undo_list: Renamed from update_undo_list.
trx_rseg_t::undo_cached: Merged from update_undo_cached
and insert_undo_cached.
trx_rseg_t::old_insert_list: Renamed from insert_undo_list.
row_purge_reset_trx_id(): New function to reset the columns.
This will be called for all undo processing in purge
that does not remove the clustered index record.
trx_undo_update_rec_get_update(): Allow trx_id=0 when copying the
old DB_TRX_ID of the record to the undo log.
ReadView::changes_visible(): Allow id==0. (Return true for it.
This is what speeds up the MVCC.)
row_vers_impl_x_locked_low(), row_vers_build_for_semi_consistent_read():
Implement a fast path for DB_TRX_ID=0.
Always initialize the TRX_UNDO_PAGE_TYPE to 0. Remove undo->type.
MLOG_UNDO_HDR_REUSE: Remove. This changes the redo log format!
innobase_start_or_create_for_mysql(): Set srv_undo_sources before
starting any transactions.
The parsing of the MLOG_ZIP_WRITE_TRX_ID record was successfully
tested by running the following:
./mtr --parallel=auto --mysqld=--debug=d,ib_log innodb_zip.bug56680
grep MLOG_ZIP_WRITE_TRX_ID var/*/log/mysqld.1.err
When the btr_search_latch was split into an array of latches
in MySQL 5.7.8 as part of the Oracle Bug#20985298 fix, the "caching"
of the latch across storage engine API calls was removed, and
the field trx->has_search_latch would only be set during a short
time frame in the execution of row_search_mvcc(), which was
formerly called row_search_for_mysql().
This means that the column
INFORMATION_SCHEMA.INNODB_TRX.TRX_ADAPTIVE_HASH_LATCHED will always
report 0. That column cannot be removed in MariaDB 10.2, but it
can be removed in future releases.
trx_t::has_search_latch: Remove.
trx_assert_no_search_latch(): Remove.
row_sel_try_search_shortcut_for_mysql(): Remove a redundant condition
on trx->has_search_latch (it was always true).
sync_check_iterate(): Make the parameter const.
sync_check_functor_t: Make the operator() const, and remove result()
and the virtual destructor. There is no need to have mutable state
in the functors.
sync_checker<bool>: Replaces dict_sync_check and btrsea_sync_check.
sync_check: Replaces btrsea_sync_check.
dict_sync_check: Instantiated from sync_checker.
sync_allowed_latches: Use std::find() directly on the array.
Remove the std::vector.
TrxInInnoDB::enter(), TrxInInnoDB::exit(): Remove obviously redundant
debug assertions on trx->in_depth, and use equality comparison against 0
because it could be more efficient on some architectures.
TrxInInnoDB should be constructed to track if a transaction is executing
inside InnoDB code i.e. it is like a gate between Server and InnoDB
::rnd_next() is called from Server and thus construct TrxInInnoDB
also there.
Applied suggested clean-up to TrxInInnoDB class functions enter()
and exit(). Note that exactly original did not work for enter().
* BEGIN_TS(), COMMIT_TS() SQL functions;
* VTQ instead of packed stores secs + usecs like my_timestamp_to_binary() does;
* versioned SELECT to IB is translated with COMMIT_TS();
* SQL fixes:
- FOR_SYSTEM_TIME_UNSPECIFIED condition compares to TIMESTAMP_MAX_VALUE;
- segfault fix#36: multiple execute of prepared stmt;
- different tables to same stored procedure fix (#39)
* Fixes of previous parts: ON DUPLICATE KEY, other misc fixes.
* moved vers_notify_vtq() to commit phase;
* low_level insert (load test passed);
* rest of SYS_VTQ columns filled: COMMIT_TS, CONCURR_TRX;
* savepoints support;
* I_S.INNODB_SYS_VTQ adjustments:
- limit to I_S_SYS_VTQ_LIMIT(10000) of most recent records;
- CONCURR_TRX limit to I_S_MAX_CONCURR_TRX(100) with '...' truncation marker;
- TIMESTAMP fields show fractions of seconds.
Problem :
---------
1. delete_all_rows() and rnd_init() are not returning error
after async rollback in 5.7. This results in assert in
innodb in next call.
2. High priority transaction is rolling back prepared transaction.
This is because TRX_FORCE_ROLLBACK_DISABLE is getting set only for
first entry [TrxInInnoDB].
Solution :
----------
1. return DB_FORCED_ABORT error after rollback.
2. check and disable rollback in TrxInInnodb::enter always.
Reviewed-by: Sunny Bains <sunny.bains@oracle.com>
RB: 13777
Introduced a new wsrep_trx_print_locking() which may be called
under lock_sys->mutex if the trx has locks.
Signed-off-by: Sachin Setiya <sachin.setiya@mariadb.com>
InnoDB divides the allocation of undo logs into rollback segments.
The DB_ROLL_PTR system column of clustered indexes can address up to
128 rollback segments (TRX_SYS_N_RSEGS). Originally, InnoDB only
created one rollback segment. In MySQL 5.5 or in the InnoDB Plugin
for MySQL 5.1, all 128 rollback segments were created.
MySQL 5.7 hard-codes the rollback segment IDs 1..32 for temporary undo logs.
On upgrade, unless a slow shutdown (innodb_fast_shutdown=0)
was performed on the old server instance, these rollback segments
could be in use by transactions that are in XA PREPARE state or
transactions that were left behind by a server kill followed by a
normal shutdown immediately after restart.
Persistent tables cannot refer to temporary undo logs or vice versa.
Therefore, we should keep two distinct sets of rollback segments:
one for persistent tables and another for temporary tables. In this way,
all 128 rollback segments will be available for both types of tables,
which could improve performance. Also, MariaDB 10.2 will remain more
compatible than MySQL 5.7 with data files from earlier versions of
MySQL or MariaDB.
trx_sys_t::temp_rsegs[TRX_SYS_N_RSEGS]: A new array of temporary
rollback segments. The trx_sys_t::rseg_array[TRX_SYS_N_RSEGS] will
be solely for persistent undo logs.
srv_tmp_undo_logs. Remove. Use the constant TRX_SYS_N_RSEGS.
srv_available_undo_logs: Change the type to ulong.
trx_rseg_get_on_id(): Remove. Instead, let the callers refer to
trx_sys directly.
trx_rseg_create(), trx_sysf_rseg_find_free(): Remove unneeded parameters.
These functions only deal with persistent undo logs.
trx_temp_rseg_create(): New function, to create all temporary rollback
segments at server startup.
trx_rseg_t::is_persistent(): Determine if the rollback segment is for
persistent tables.
trx_sys_is_noredo_rseg_slot(): Remove. The callers must know based on
context (such as table handle) whether the DB_ROLL_PTR is referring to
a persistent undo log.
trx_sys_create_rsegs(): Remove all parameters, which were always passed
as global variables. Instead, modify the global variables directly.
enum trx_rseg_type_t: Remove.
trx_t::get_temp_rseg(): A method to ensure that a temporary
rollback segment has been assigned for the transaction.
trx_t::assign_temp_rseg(): Replaces trx_assign_rseg().
trx_purge_free_segment(), trx_purge_truncate_rseg_history():
Remove the redundant variable noredo=false.
Temporary undo logs are discarded immediately at transaction commit
or rollback, not lazily by purge.
trx_purge_mark_undo_for_truncate(): Remove references to the
temporary rollback segments.
trx_purge_mark_undo_for_truncate(): Remove a check for temporary
rollback segments. Only the dedicated persistent undo log tablespaces
can be truncated.
trx_undo_get_undo_rec_low(), trx_undo_get_undo_rec(): Add the
parameter is_temp.
trx_rseg_mem_restore(): Split from trx_rseg_mem_create().
Initialize the undo log and the rollback segment from the file
data structures.
trx_sysf_get_n_rseg_slots(): Renamed from
trx_sysf_used_slots_for_redo_rseg(). Count the persistent
rollback segment headers that have been initialized.
trx_sys_close(): Also free trx_sys->temp_rsegs[].
get_next_redo_rseg(): Merged to trx_assign_rseg_low().
trx_assign_rseg_low(): Remove the parameters and access the
global variables directly. Revert to simple round-robin, now that
the whole trx_sys->rseg_array[] is for persistent undo log again.
get_next_noredo_rseg(): Moved to trx_t::assign_temp_rseg().
srv_undo_tablespaces_init(): Remove some parameters and use the
global variables directly. Clarify some error messages.
Adjust the test innodb.log_file. Apparently, before these changes,
InnoDB somehow ignored missing dedicated undo tablespace files that
are pointed by the TRX_SYS header page, possibly losing part of
essential transaction system state.
trx::has_logged_persistent(): Renamed from trx_is_redo_rseg_updated().
Determines if a transaction has generated any persistent undo log.
trx::has_logged(): Renamed from trx_is_rseg_updated().
Determines if a transaction has generated any undo log.
Problem was that trx_sys->mutex was acquired to print trx info
even when we already hold trx_sys->mutex. Fixed similarly as
in InnoDB, i.e. with wsrep_trx_print_locking() function that
does not acquire trx_sys->mutex.
InnoDB defines some functions that are not called at all.
Other functions are called, but only from the same compilation unit.
Remove some function declarations and definitions, and add 'static'
keywords. Some symbols must be kept for separately compiled tools,
such as innochecksum.
Also, remove empty .ic files that were not removed by my MySQL commit.
Problem:
InnoDB used to support a compilation mode that allowed to choose
whether the function definitions in .ic files are to be inlined or not.
This stopped making sense when InnoDB moved to C++ in MySQL 5.6
(and ha_innodb.cc started to #include .ic files), and more so in
MySQL 5.7 when inline methods and functions were introduced
in .h files.
Solution:
Remove all references to UNIV_NONINL and UNIV_MUST_NOT_INLINE from
all files, assuming that the symbols are never defined.
Remove the files fut0fut.cc and ut0byte.cc which only mattered when
UNIV_NONINL was defined.
Introduced a new wsrep_trx_print_locking() which may be called
under lock_sys->mutex if the trx has locks.
Signed-off-by: Sachin Setiya <sachinsetia1001@gmail.com>
Starting with MySQL 5.7, temporary tables in InnoDB are handled
differently from persistent tables. Because temporary tables are
private to a connection, concurrency control and multi-versioning
(MVCC) are not applicable. For performance reasons, purge is
disabled as well. Rollback is supported for temporary tables;
that is why we have the temporary undo logs in the first place.
Because MVCC and purge are disabled for temporary tables, we should
discard all temporary undo logs already at transaction commit,
just like we discard the persistent insert_undo logs. Before this
change, update_undo logs were being preserved.
trx_temp_undo_t: A wrapper for temporary undo logs, comprising
a rollback segment and a single temporary undo log.
trx_rsegs_t::m_noredo: Use trx_temp_undo_t.
(Instead of insert_undo, update_undo, there will be a single undo.)
trx_is_noredo_rseg_updated(), trx_is_rseg_assigned(): Remove.
trx_undo_add_page(): Remove the parameter undo_ptr.
Acquire and release the rollback segment mutex inside the function.
trx_undo_free_last_page(): Remove the parameter trx.
trx_undo_truncate_end(): Remove the parameter trx, and add the
parameter is_temp. Clean up the code a bit.
trx_undo_assign_undo(): Split the parameter undo_ptr into rseg, undo.
trx_undo_commit_cleanup(): Renamed from trx_undo_insert_cleanup().
Replace the parameter undo_ptr with undo.
This will discard the temporary undo or insert_undo log at
commit/rollback.
trx_purge_add_update_undo_to_history(), trx_undo_update_cleanup():
Remove 3 parameters. Always operate on the persistent update_undo.
trx_serialise(): Renamed from trx_serialisation_number_get().
trx_write_serialisation_history(): Simplify the code flow.
If there are no persistent changes, do not update MONITOR_TRX_COMMIT_UNDO.
trx_commit_in_memory(): Simplify the logic, and add assertions.
trx_undo_page_report_modify(): Keep a direct reference to the
persistent update_undo log.
trx_undo_report_row_operation(): Simplify some code.
Always assign TRX_UNDO_INSERT for temporary undo logs.
trx_prepare_low(): Keep only one parameter. Prepare all 3 undo logs.
trx_roll_try_truncate(): Remove the parameter undo_ptr.
Try to truncate all 3 undo logs of the transaction.
trx_roll_pop_top_rec_of_trx_low(): Remove.
trx_roll_pop_top_rec_of_trx(): Remove the redundant parameter
trx->roll_limit. Clear roll_limit when exhausting the undo logs.
Consider all 3 undo logs at once, prioritizing the persistent
undo logs.
row_undo(): Minor cleanup. Let trx_roll_pop_top_rec_of_trx()
reset the trx->roll_limit.
InnoDB needs to collect transactions from the persistent data files
in trx_rseg_array_init() before trx_lists_init_at_db_start() is
executed. But there is no need to create purge_sys->purge_queue
separately from purge_sys.
trx_sys_init_at_db_start(): Change the return type to void.
Remove the direct call to trx_rseg_array_init(). It will be called
by trx_lists_init_at_db_start(), which we are calling.
Initialize the purge system read view.
trx_lists_init_at_db_start(): Call trx_purge_sys_create(), which will
invoke trx_rseg_array_init() to read the undo log segments.
trx_purge_sys_create(): Remove the parameters. Do not initialize
the purge system read view, because trx_sys->rw_trx_list has not
been recovered yet. The purge_sys->view will be initialized at
the end of trx_sys_init_at_db_start().
trx_rseg_array_init(): Remove the parameter. Use purge_sys->purge_queue
directly.
innobase_start_or_create_for_mysql(): Remove the local variable
purge_queue. Do not call trx_purge_sys_create(), because it will be
called by trx_sys_init_at_db_start().
