The trx_t::undo_mutex covered both some main-memory data structures
(trx_undo_t) and access to undo pages. The trx_undo_t is only
accessed by the thread that is associated with a running transaction.
Likewise, each transaction has its private set of undo pages.
The thread that is associated with an active transaction may
lock multiple undo pages concurrently, but no other thread may
lock multiple pages of a foreign transaction.
Concurrent access to the undo logs of an active transaction is possible,
but trx_undo_get_undo_rec_low() only locks one undo page at a time,
without ever holding any undo_mutex.
It seems that the trx_t::undo_mutex would have been necessary if
multi-threaded execution or rollback of a single transaction
had been implemented in InnoDB.
Problem was that if tablespace was encrypted we try to copy
also page 0 from read buffer to write buffer that are in
that case the same memory area.
fil_iterate
When tablespace is encrypted or compressed its
first page (i.e. page 0) is not encrypted or
compressed and there is no need to copy buffer.
row_ins_sec_index_entry(): Compare a pointer to fil_system.sys_space,
not to a numeric constant. This code was recently changed in MDEV-13637,
and the condition was essentially disabled, potentially causing the
change buffer to grow uncontrollably when something is inserted into
a table that has secondary indexes and resides in the system tablespace.
Thanks to Daniel Black for pointing out that clang 7 flagged a warning
for the comparison of a pointer to an integer.
row_import_for_mysql(): Fix a possible compiler warning.
InnoDB always keeps all tablespaces in the fil_system cache.
The fil_system.LRU is only for closing file handles; the
fil_space_t and fil_node_t for all data files will remain
in main memory. Between startup to shutdown, they can only be
created and removed by DDL statements. Therefore, we can
let dict_table_t::space point directly to the fil_space_t.
dict_table_t::space_id: A numeric tablespace ID for the corner cases
where we do not have a tablespace. The most prominent examples are
ALTER TABLE...DISCARD TABLESPACE or a missing or corrupted file.
There are a few functional differences; most notably:
(1) DROP TABLE will delete matching .ibd and .cfg files,
even if they were not attached to the data dictionary.
(2) Some error messages will report file names instead of numeric IDs.
There still are many functions that use numeric tablespace IDs instead
of fil_space_t*, and many functions could be converted to fil_space_t
member functions. Also, Tablespace and Datafile should be merged with
fil_space_t and fil_node_t. page_id_t and buf_page_get_gen() could use
fil_space_t& instead of a numeric ID, and after moving to a single
buffer pool (MDEV-15058), buf_pool_t::page_hash could be moved to
fil_space_t::page_hash.
FilSpace: Remove. Only few calls to fil_space_acquire() will remain,
and gradually they should be removed.
mtr_t::set_named_space_id(ulint): Renamed from set_named_space(),
to prevent accidental calls to this slower function. Very few
callers remain.
fseg_create(), fsp_reserve_free_extents(): Take fil_space_t*
as a parameter instead of a space_id.
fil_space_t::rename(): Wrapper for fil_rename_tablespace_check(),
fil_name_write_rename(), fil_rename_tablespace(). Mariabackup
passes the parameter log=false; InnoDB passes log=true.
dict_mem_table_create(): Take fil_space_t* instead of space_id
as parameter.
dict_process_sys_tables_rec_and_mtr_commit(): Replace the parameter
'status' with 'bool cached'.
dict_get_and_save_data_dir_path(): Avoid copying the fil_node_t::name.
fil_ibd_open(): Return the tablespace.
fil_space_t::set_imported(): Replaces fil_space_set_imported().
truncate_t: Change many member function parameters to fil_space_t*,
and remove page_size parameters.
row_truncate_prepare(): Merge to its only caller.
row_drop_table_from_cache(): Assert that the table is persistent.
dict_create_sys_indexes_tuple(): Write SYS_INDEXES.SPACE=FIL_NULL
if the tablespace has been discarded.
row_import_update_discarded_flag(): Remove a constant parameter.
We can rely on the dict_table_t::space. All indexes of a table object
are always in the same tablespace. (For fulltext indexes, the data is
located in auxiliary tables, and these will continue to have their own
table objects, separate from the main table.)
fil_iterate(), fil_tablespace_iterate(): Replace os_file_read()
with os_file_read_no_error_handling().
os_file_read_func(), os_file_read_no_error_handling_func():
Do not retry partial reads. There used to be an infinite amount
of retries. Because InnoDB extends both data and log files upfront,
partial reads should be impossible during normal operation.
Initialize block.page.zip only once.
PageConverter::update(): Initialize m_page_zip_ptr
as late as possible.
(We should really remove it at some point.)
PageConverter::operator(): Refer to block->page.zip instead of
m_page_zip_ptr.
AbstractCallback::get_frame(): Define static. Refer
to block->page.zip.data directly.
fil_iterate(): Refer to block->page.zip.data directly.
fil_tablespace_iterate(): Initialize block.page.zip.data as soon
as possible.
Reduce unnecessary inter-module calls for IMPORT TABLESPACE.
Move some IMPORT-related code from fil0fil.cc to row0import.cc.
PageCallback: Remove. Make AbstractCallback the base class.
PageConverter: Define some member functions inline.
PageConverter::adjust_cluster_record(): Instead of writing
the invalid value DB_ROLL_PTR=0, write a value that indicates
a fresh insert, that is, prevents the DB_ROLL_PTR from being
dereferenced in any circumstances.
It can be argued that IMPORT TABLESPACE should actually
update the dict_index_t::trx_id to prevent older transactions
from accessing the table, similar to what I did on table
rebuild in MySQL 5.6.6 in
03f81a55f2
Rollback attempted to dereference DB_ROLL_PTR=0, which cannot possibly
be a valid undo log pointer. A safer canonical value would be
roll_ptr_t(1) << ROLL_PTR_INSERT_FLAG_POS
which is what was chosen in MDEV-12288, corresponding to reset_trx_id.
No deterministic test case for the bug was found. The simplest test
cases may be related to MDEV-11415, which suppresses undo logging for
ALGORITHM=COPY operations. In those operations, in the spirit of
MDEV-12288, we should actually have written reset_trx_id instead of
using the transaction identifier of the current transaction
(and a bogus value of DB_ROLL_PTR=0). However, thanks to MySQL Bug#28432
which I had fixed in MySQL 5.6.8 as part of WL#6255, access to the
rebuilt table by earlier-started transactions should actually have been
refused with ER_TABLE_DEF_CHANGED.
reset_trx_id: Move the definition to data0type.cc and the declaration
to data0type.h.
btr_cur_ins_lock_and_undo(): When undo logging is disabled, use the
safe value that corresponds to reset_trx_id.
btr_cur_optimistic_insert(): Validate the DB_TRX_ID,DB_ROLL_PTR before
inserting into a clustered index leaf page.
ins_node_t::sys_buf[]: Replaces row_id_buf and trx_id_buf and some
heap usage.
row_ins_alloc_sys_fields(): Init ins_node_t::sys_buf[] to reset_trx_id.
row_ins_buf(): Only if undo logging is enabled, copy trx->id
to node->sys_buf. Otherwise, rely on the initialization in
row_ins_alloc_sys_fields().
row_purge_reset_trx_id(): Invoke mlog_write_string() with reset_trx_id
directly. (No functional change.)
trx_undo_page_report_modify(): Assert that the DB_ROLL_PTR is not 0.
trx_undo_get_undo_rec_low(): Assert that the roll_ptr is valid before
trying to dereference it.
dict_index_t::is_primary(): Check if the index is the primary key.
PageConverter::adjust_cluster_record(): Fix
MDEV-15249 Crash in MVCC read after IMPORT TABLESPACE
by resetting the system fields to reset_trx_id instead of writing
the current transaction ID (which will be committed at the
end of the IMPORT TABLESPACE) and DB_ROLL_PTR=0.
This can partially be viewed as a follow-up fix of MDEV-12288,
because IMPORT should already then have written
DB_TRX_ID=0 and DB_ROLL_PTR=1<<55 to prevent unnecessary
DB_TRX_ID lookups in subsequent accesses to the table.
Remove unnecessary repeated lookups for undo pages.
trx_undo_assign(), trx_undo_assign_low(), trx_undo_seg_create(),
trx_undo_create(): Return the undo log block to the caller.
Inside InnoDB, each mini-transaction that generates any redo log records
will acquire log_sys->mutex during mtr_t::commit() in order to copy the
records into the global log_sys->buf for writing into the redo log file.
For single-row transactions, this incurs quite a bit of overhead.
We would use two mini-transactions for writing a record into a
freshly updated undo log page. (Only if the undo record will
not fit in that page, then we will have to commit and restart
the mini-transaction.)
trx_undo_assign(): Assign undo log for a persistent transaction,
or return the already assigned one.
trx_undo_assign_low(): Assign undo log for an operation on a
persistent or temporary table.
trx_undo_create(), trx_undo_reuse_cached(): Remove redundant parameters.
Merge the logic from trx_undo_mark_as_dict_operation().
Also, MDEV-14317 When ALTER TABLE is aborted, do not write garbage pages to data files
As pointed out by Shaohua Wang, the merge of MDEV-13328 from
MariaDB 10.1 (based on MySQL 5.6) to 10.2 (based on 5.7)
was performed incorrectly.
Let us always pass a non-NULL FlushObserver* when writing
to data files is desired.
FlushObserver::is_partial_flush(): Check if this is a bulk-load
(partial flush of the tablespace).
FlushObserver::is_interrupted(): Check for interrupt status.
buf_LRU_flush_or_remove_pages(): Instead of trx_t*, take
FlushObserver* as a parameter.
buf_flush_or_remove_pages(): Remove the parameters flush, trx.
If observer!=NULL, write out the data pages. Use the new predicate
observer->is_partial() to distinguish a partial tablespace flush
(after bulk-loading) from a full tablespace flush (export).
Return a bool (whether all pages were removed from the flush_list).
buf_flush_dirty_pages(): Remove the parameter trx.
With a big buffer pool that contains many data pages,
DISCARD TABLESPACE took a long time, because it would scan the
entire buffer pool to remove any pages that belong to the tablespace.
With a large buffer pool, this would take a lot of time, especially
when the table-to-discard is empty.
The minimum amount of work that DISCARD TABLESPACE must do is to
remove the pages of the to-be-discarded table from the
buf_pool->flush_list because any writes to the data file must be
prevented before the file is deleted.
If DISCARD TABLESPACE does not evict the pages from the buffer pool,
then IMPORT TABLESPACE must do it, because we must prevent pre-DISCARD,
not-yet-evicted pages from being mistaken for pages of the imported
tablespace.
It would not be a useful fix to simply move the buffer pool scan to
the IMPORT TABLESPACE step. What we can do is to actively evict those
pages that could be mistaken for imported pages. In this way, when
importing a small table into a big buffer pool, the import should
still run relatively fast.
Import is bypassing the buffer pool when reading pages for the
adjustment phase. In the adjustment phase, if a page exists in
the buffer pool, we could replace it with the page from the imported
file. Unfortunately I did not get this to work properly, so instead
we will simply evict any matching page from the buffer pool.
buf_page_get_gen(): Implement BUF_EVICT_IF_IN_POOL, a new mode
where the requested page will be evicted if it is found. There
must be no unwritten changes for the page.
buf_remove_t: Remove. Instead, use trx!=NULL to signify that a write
to file is desired, and use a separate parameter bool drop_ahi.
buf_LRU_flush_or_remove_pages(), fil_delete_tablespace():
Replace buf_remove_t.
buf_LRU_remove_pages(), buf_LRU_remove_all_pages(): Remove.
PageConverter::m_mtr: A dummy mini-transaction buffer
PageConverter::PageConverter(): Complete the member initialization list.
PageConverter::operator()(): Evict any 'shadow' pages from the
buffer pool so that pre-existing (garbage) pages cannot be mistaken
for pages that exist in the being-imported file.
row_discard_tablespace(): Remove a bogus comment that seems to
refer to IMPORT TABLESPACE, not DISCARD TABLESPACE.
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().
The ALTER TABLE…IMPORT TABLESPACE adjustment code that was introduced by
WL#5522 in MySQL 5.6 is incorrectly invoking rec_get_status() on a
ROW_FORMAT=REDUNDANT record to determine if a record is a leaf page record.
The function rec_get_status(rec) is only to be called on
ROW_FORMAT=COMPACT, DYNAMIC or COMPRESSED records.
This should affect debug builds only. Debug builds will check that
the status bits of ROW_FORMAT!=REDUNDANT records match the is_leaf
parameter.
The only observable change to non-debug should be the addition of
the is_leaf parameter to the function rec_copy_prefix_to_dtuple(),
and the removal of some calls to update the adaptive hash index
(it is only built for the leaf pages).
This change should have been made in MySQL 5.0.3, instead of
introducing the status flags in the ROW_FORMAT=COMPACT record header.
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 using innodb_page_size=16k, InnoDB tables
that were created in MariaDB 10.1.0 to 10.1.20 with
PAGE_COMPRESSED=1 and
PAGE_COMPRESSION_LEVEL=2 or PAGE_COMPRESSION_LEVEL=3
would fail to load.
fsp_flags_is_valid(): When using innodb_page_size=16k, use a
more strict check for .ibd files, with the assumption that
nobody would try to use different-page-size files.
When using innodb_page_size=16k, InnoDB tables
that were created in MariaDB 10.1.0 to 10.1.20 with
PAGE_COMPRESSED=1 and
PAGE_COMPRESSION_LEVEL=2 or PAGE_COMPRESSION_LEVEL=3
would fail to load.
fsp_flags_is_valid(): When using innodb_page_size=16k, use a
more strict check for .ibd files, with the assumption that
nobody would try to use different-page-size files.
innodb.table_flags: Adjust the test case. Due to the MDEV-12873 fix
in 10.2, the corrupted flags for table test.td would be converted,
and a tablespace flag mismatch will occur when trying to open the file.
Remove the SHARED_SPACE flag that was erroneously introduced in
MariaDB 10.2.2, and shift the SYS_TABLES.TYPE flags back to where
they were before MariaDB 10.2.2. While doing this, ensure that
tables created with affected MariaDB versions can be loaded,
and also ensure that tables created with MySQL 5.7 using the
TABLESPACE attribute cannot be loaded.
MariaDB 10.2.2 picked the SHARED_SPACE flag from MySQL 5.7,
shifting the MariaDB 10.1 flags PAGE_COMPRESSION, PAGE_COMPRESSION_LEVEL,
ATOMIC_WRITES by one bit. The SHARED_SPACE flag would always
be written as 0 by MariaDB, because MariaDB does not support
CREATE TABLESPACE or CREATE TABLE...TABLESPACE for InnoDB.
So, instead of the bits AALLLLCxxxxxxx we would have
AALLLLC0xxxxxxx if the table was created with MariaDB 10.2.2
to 10.2.6. (AA=ATOMIC_WRITES, LLLL=PAGE_COMPRESSION_LEVEL,
C=PAGE_COMPRESSED, xxxxxxx=7 bits that were not moved.)
PAGE_COMPRESSED=NO implies LLLLC=00000. That is not a problem.
If someone created a table in MariaDB 10.2.2 or 10.2.3 with
the attribute ATOMIC_WRITES=OFF (value 2; AA=10) and without
PAGE_COMPRESSED=YES or PAGE_COMPRESSION_LEVEL, the table should be
rejected. We ignore this problem, because it should be unlikely
for anyone to specify ATOMIC_WRITES=OFF, and because 10.2.2 and
10.2.2 were not mature releases. The value ATOMIC_WRITES=ON (1)
would be interpreted as ATOMIC_WRITES=OFF, but starting with
MariaDB 10.2.4 the ATOMIC_WRITES attribute is ignored.
PAGE_COMPRESSED=YES implies that PAGE_COMPRESSION_LEVEL be between
1 and 9 and that ROW_FORMAT be COMPACT or DYNAMIC. Thus, the affected
wrong bit pattern in SYS_TABLES.TYPE is of the form AALLLL10DB00001
where D signals the presence of a DATA DIRECTORY attribute and B is 1
for ROW_FORMAT=DYNAMIC and 0 for ROW_FORMAT=COMPACT. We must interpret
this bit pattern as AALLLL1DB00001 (discarding the extraneous 0 bit).
dict_sys_tables_rec_read(): Adjust the affected bit pattern when
reading the SYS_TABLES.TYPE column. In case of invalid flags,
report both SYS_TABLES.TYPE (after possible adjustment) and
SYS_TABLES.MIX_LEN.
dict_load_table_one(): Replace an unreachable condition on
!dict_tf2_is_valid() with a debug assertion. The flags will already
have been validated by dict_sys_tables_rec_read(); if that validation
fails, dict_load_table_low() will have failed.
fil_ibd_create(): Shorten an error message about a file pre-existing.
Datafile::validate_to_dd(): Clarify an error message about tablespace
flags mismatch.
ha_innobase::open(): Remove an unnecessary warning message.
dict_tf_is_valid(): Simplify and stricten the logic. Validate the
values of PAGE_COMPRESSION. Remove error log output; let the callers
handle that.
DICT_TF_BITS: Remove ATOMIC_WRITES, PAGE_ENCRYPTION, PAGE_ENCRYPTION_KEY.
The ATOMIC_WRITES is ignored once the SYS_TABLES.TYPE has been validated;
there is no need to store it in dict_table_t::flags. The PAGE_ENCRYPTION
and PAGE_ENCRYPTION_KEY are unused since MariaDB 10.1.4 (the GA release
was 10.1.8).
DICT_TF_BIT_MASK: Remove (unused).
FSP_FLAGS_MEM_ATOMIC_WRITES: Remove (the flags are never read).
row_import_read_v1(): Display an error if dict_tf_is_valid() fails.
dict_table_t::thd: Remove. This was only used by btr_root_block_get()
for reporting decryption failures, and it was only assigned by
ha_innobase::open(), and never cleared. This could mean that if a
connection is closed, the pointer would become stale, and the server
could crash while trying to report the error. It could also mean
that an error is being reported to the wrong client. It is better
to use current_thd in this case, even though it could mean that if
the code is invoked from an InnoDB background operation, there would
be no connection to which to send the error message.
Remove dict_table_t::crypt_data and dict_table_t::page_0_read.
These fields were never read.
fil_open_single_table_tablespace(): Remove the parameter "table".
