This is a complete rewrite of DROP TABLE, also as part of other DDL,
such as ALTER TABLE, CREATE TABLE...SELECT, TRUNCATE TABLE.
The background DROP TABLE queue hack is removed.
If a transaction needs to drop and create a table by the same name
(like TRUNCATE TABLE does), it must first rename the table to an
internal #sql-ib name. No committed version of the data dictionary
will include any #sql-ib tables, because whenever a transaction
renames a table to a #sql-ib name, it will also drop that table.
Either the rename will be rolled back, or the drop will be committed.
Data files will be unlinked after the transaction has been committed
and a FILE_RENAME record has been durably written. The file will
actually be deleted when the detached file handle returned by
fil_delete_tablespace() will be closed, after the latches have been
released. It is possible that a purge of the delete of the SYS_INDEXES
record for the clustered index will execute fil_delete_tablespace()
concurrently with the DDL transaction. In that case, the thread that
arrives later will wait for the other thread to finish.
HTON_TRUNCATE_REQUIRES_EXCLUSIVE_USE: A new handler flag.
ha_innobase::truncate() now requires that all other references to
the table be released in advance. This was implemented by Monty.
ha_innobase::delete_table(): If CREATE TABLE..SELECT is detected,
we will "hijack" the current transaction, drop the table in
the current transaction and commit the current transaction.
This essentially fixes MDEV-21602. There is a FIXME comment about
making the check less failure-prone.
ha_innobase::truncate(), ha_innobase::delete_table():
Implement a fast path for temporary tables. We will no longer allow
temporary tables to use the adaptive hash index.
dict_table_t::mdl_name: The original table name for the purpose of
acquiring MDL in purge, to prevent a race condition between a
DDL transaction that is dropping a table, and purge processing
undo log records of DML that had executed before the DDL operation.
For #sql-backup- tables during ALTER TABLE...ALGORITHM=COPY, the
dict_table_t::mdl_name will differ from dict_table_t::name.
dict_table_t::parse_name(): Use mdl_name instead of name.
dict_table_rename_in_cache(): Update mdl_name.
For the internal FTS_ tables of FULLTEXT INDEX, purge would
acquire MDL on the FTS_ table name, but not on the main table,
and therefore it would be able to run concurrently with a
DDL transaction that is dropping the table. Previously, the
DROP TABLE queue hack prevented a race between purge and DDL.
For now, we introduce purge_sys.stop_FTS() to prevent purge from
opening any table, while a DDL transaction that may drop FTS_
tables is in progress. The function fts_lock_table(), which will
be invoked before the dictionary is locked, will wait for
purge to release any table handles.
trx_t::drop_table_statistics(): Drop statistics for the table.
This replaces dict_stats_drop_index(). We will drop or rename
persistent statistics atomically as part of DDL transactions.
On lock conflict for dropping statistics, we will fail instantly
with DB_LOCK_WAIT_TIMEOUT, because we will be holding the
exclusive data dictionary latch.
trx_t::commit_cleanup(): Separated from trx_t::commit_in_memory().
Relax an assertion around fts_commit() and allow DB_LOCK_WAIT_TIMEOUT
in addition to DB_DUPLICATE_KEY. The call to fts_commit() is
entirely misplaced here and may obviously break the consistency
of transactions that affect FULLTEXT INDEX. It needs to be fixed
separately.
dict_table_t::n_foreign_key_checks_running: Remove (MDEV-21175).
The counter was a work-around for missing meta-data locking (MDL)
on the SQL layer, and not really needed in MariaDB.
ER_TABLE_IN_FK_CHECK: Replaced with ER_UNUSED_28.
HA_ERR_TABLE_IN_FK_CHECK: Remove.
row_ins_check_foreign_constraints(): Do not acquire
dict_sys.latch either. The SQL-layer MDL will protect us.
This was reviewed by Thirunarayanan Balathandayuthapani
and tested by Matthias Leich.
Before we create an InnoDB data file, we must have persistently
started a DDL transaction and written a record in SYS_INDEXES
as well as a FILE_CREATE record for creating the file.
In that way, if InnoDB is killed before the DDL transaction is
committed, the rollback will be able to delete the file in
dict_drop_index_tree().
dict_build_table_def_step(): Do not create the tablespace.
At this point, we have not written any log, not even for
inserting the SYS_TABLES record.
dict_create_sys_indexes_tuple(): Relax an assertion to tolerate
a missing tablespace before the first index has been created in
dict_create_index_step().
dict_build_index_def_step(): Relax the dict_table_open_on_name()
parameter, because no tablespace may be available yet.
tab_create_graph_create(), row_create_table_for_mysql(), tab_node_t:
Remove key_id, mode.
ind_create_graph_create(), row_create_index_for_mysql(), ind_node_t:
Add key_id, mode.
dict_create_index_space(): New function, to create the tablespace
during clustered index creation.
dict_create_index_step(): After the SYS_INDEXES record has been
written, invoke dict_create_index_space() to create the tablespace
if needed.
fil_ibd_create(): Before creating the file, persistently write a
FILE_CREATE record. This will also ensure that an incomplete DDL
transaction will be recovered. After creating the file, invoke
fsp_header_init().
Let us introduce the parameter innodb_read_only_compressed
that is ON by default, making any ROW_FORMAT=COMPRESSED tables
read-only.
I developed the ROW_FORMAT=COMPRESSED format based on
Heikki Tuuri's rough design between 2005 and 2008. It might
have been a good idea back then, but no proper benchmarks were
ever run to validate the design or the implementation.
The format has been more or less obsolete for years.
It limits innodb_page_size to 16384 bytes (the default),
and instant ALTER TABLE is not supported.
This is the first step towards deprecating and removing
write support for ROW_FORMAT=COMPRESSED tables.
After DISCARD TABLESPACE, the tablespace of a table will no longer
exist, and dict_get_and_save_data_dir_path() would invoke
dict_get_first_path() to read an entry from SYS_DATAFILES.
For some reason, DISCARD TABLESPACE would not to remove the entry
from there.
dict_get_and_save_data_dir_path(): If the tablespace has been
discarded, do not bother trying to read the name.
Side note: The tables SYS_TABLESPACES and SYS_DATAFILES are
redundant and subject to removal in MDEV-22343.
ha_innobase::truncate(): Because CREATE TEMPORARY TABLE
allows invalid table options when innodb_file_per_table=1,
do allow them also in TRUNCATE for temporary tables.
This is a regression due to MDEV-17816.
When creating a table fails, we must roll back the dictionary
transaction. Because the rollback may rename tables, and because
InnoDB lacks proper undo logging for CREATE operations, we must
drop the incompletely created table before rolling back the
transaction, which could include a RENAME operation.
But, we must not blindly drop the table by name; after all,
the operation could have failed because another table by the
same name already existed.
create_table_info_t::m_drop_before_rollback: A flag that is set
if the table needs to be dropped before transaction rollback.
create_table_info_t::create_table(): Remove some duplicated
error handling.
ha_innobase::create(): On error, only drop the table if it was
actually created.
If a table had a KEY_BLOCK_SIZE attribute, but no ROW_FORMAT,
it would be created as ROW_FORMAT=COMPRESSED in InnoDB.
However, TRUNCATE TABLE would lose the KEY_BLOCK_SIZE attribute
and create the table with the innodb_default_row_format (DYNAMIC).
This is a regression that was introduced by MDEV-13564.
update_create_info_from_table(): Copy also KEY_BLOCK_SIZE.
The error handling in the MDEV-13564 TRUNCATE TABLE was broken
when an error occurred during table creation.
row_create_index_for_mysql(): Do not drop the table on error.
fts_create_one_common_table(), fts_create_one_index_table():
Do drop the table on error.
create_index(), create_table_info_t::create_table():
Let the caller handle the index creation errors.
ha_innobase::create(): If create_table_info_t::create_table()
fails, drop the incomplete table, roll back the transaction,
and finally return an error to the caller.
Implement undo tablespace truncation via normal redo logging.
Implement TRUNCATE TABLE as a combination of RENAME to #sql-ib name,
CREATE, and DROP.
Note: Orphan #sql-ib*.ibd may be left behind if MariaDB Server 10.2
is killed before the DROP operation is committed. If MariaDB Server 10.2
is killed during TRUNCATE, it is also possible that the old table
was renamed to #sql-ib*.ibd but the data dictionary will refer to the
table using the original name.
In MariaDB Server 10.3, RENAME inside InnoDB is transactional,
and #sql-* tables will be dropped on startup. So, this new TRUNCATE
will be fully crash-safe in 10.3.
ha_mroonga::wrapper_truncate(): Pass table options to the underlying
storage engine, now that ha_innobase::truncate() will need them.
rpl_slave_state::truncate_state_table(): Before truncating
mysql.gtid_slave_pos, evict any cached table handles from
the table definition cache, so that there will be no stale
references to the old table after truncating.
== TRUNCATE TABLE ==
WL#6501 in MySQL 5.7 introduced separate log files for implementing
atomic and crash-safe TRUNCATE TABLE, instead of using the InnoDB
undo and redo log. Some convoluted logic was added to the InnoDB
crash recovery, and some extra synchronization (including a redo log
checkpoint) was introduced to make this work. This synchronization
has caused performance problems and race conditions, and the extra
log files cannot be copied or applied by external backup programs.
In order to support crash-upgrade from MariaDB 10.2, we will keep
the logic for parsing and applying the extra log files, but we will
no longer generate those files in TRUNCATE TABLE.
A prerequisite for crash-safe TRUNCATE is a crash-safe RENAME TABLE
(with full redo and undo logging and proper rollback). This will
be implemented in MDEV-14717.
ha_innobase::truncate(): Invoke RENAME, create(), delete_table().
Because RENAME cannot be fully rolled back before MariaDB 10.3
due to missing undo logging, add some explicit rename-back in
case the operation fails.
ha_innobase::delete(): Introduce a variant that takes sqlcom as
a parameter. In TRUNCATE TABLE, we do not want to touch any
FOREIGN KEY constraints.
ha_innobase::create(): Add the parameters file_per_table, trx.
In TRUNCATE, the new table must be created in the same transaction
that renames the old table.
create_table_info_t::create_table_info_t(): Add the parameters
file_per_table, trx.
row_drop_table_for_mysql(): Replace a bool parameter with sqlcom.
row_drop_table_after_create_fail(): New function, wrapping
row_drop_table_for_mysql().
dict_truncate_index_tree_in_mem(), fil_truncate_tablespace(),
fil_prepare_for_truncate(), fil_reinit_space_header_for_table(),
row_truncate_table_for_mysql(), TruncateLogger,
row_truncate_prepare(), row_truncate_rollback(),
row_truncate_complete(), row_truncate_fts(),
row_truncate_update_system_tables(),
row_truncate_foreign_key_checks(), row_truncate_sanity_checks():
Remove.
row_upd_check_references_constraints(): Remove a check for
TRUNCATE, now that the table is no longer truncated in place.
The new test innodb.truncate_foreign uses DEBUG_SYNC to cover some
race-condition like scenarios. The test innodb-innodb.truncate does
not use any synchronization.
We add a redo log subformat to indicate backup-friendly format.
MariaDB 10.4 will remove support for the old TRUNCATE logging,
so crash-upgrade from old 10.2 or 10.3 to 10.4 will involve
limitations.
== Undo tablespace truncation ==
MySQL 5.7 implements undo tablespace truncation. It is only
possible when innodb_undo_tablespaces is set to at least 2.
The logging is implemented similar to the WL#6501 TRUNCATE,
that is, using separate log files and a redo log checkpoint.
We can simply implement undo tablespace truncation within
a single mini-transaction that reinitializes the undo log
tablespace file. Unfortunately, due to the redo log format
of some operations, currently, the total redo log written by
undo tablespace truncation will be more than the combined size
of the truncated undo tablespace. It should be acceptable
to have a little more than 1 megabyte of log in a single
mini-transaction. This will be fixed in MDEV-17138 in
MariaDB Server 10.4.
recv_sys_t: Add truncated_undo_spaces[] to remember for which undo
tablespaces a MLOG_FILE_CREATE2 record was seen.
namespace undo: Remove some unnecessary declarations.
fil_space_t::is_being_truncated: Document that this flag now
only applies to undo tablespaces. Remove some references.
fil_space_t::is_stopping(): Do not refer to is_being_truncated.
This check is for tablespaces of tables. Potentially used
tablespaces are never truncated any more.
buf_dblwr_process(): Suppress the out-of-bounds warning
for undo tablespaces.
fil_truncate_log(): Write a MLOG_FILE_CREATE2 with a nonzero
page number (new size of the tablespace in pages) to inform
crash recovery that the undo tablespace size has been reduced.
fil_op_write_log(): Relax assertions, so that MLOG_FILE_CREATE2
can be written for undo tablespaces (without .ibd file suffix)
for a nonzero page number.
os_file_truncate(): Add the parameter allow_shrink=false
so that undo tablespaces can actually be shrunk using this function.
fil_name_parse(): For undo tablespace truncation,
buffer MLOG_FILE_CREATE2 in truncated_undo_spaces[].
recv_read_in_area(): Avoid reading pages for which no redo log
records remain buffered, after recv_addr_trim() removed them.
trx_rseg_header_create(): Add a FIXME comment that we could write
much less redo log.
trx_undo_truncate_tablespace(): Reinitialize the undo tablespace
in a single mini-transaction, which will be flushed to the redo log
before the file size is trimmed.
recv_addr_trim(): Discard any redo logs for pages that were
logged after the new end of a file, before the truncation LSN.
If the rec_list becomes empty, reduce n_addrs. After removing
any affected records, actually truncate the file.
recv_apply_hashed_log_recs(): Invoke recv_addr_trim() right before
applying any log records. The undo tablespace files must be open
at this point.
buf_flush_or_remove_pages(), buf_flush_dirty_pages(),
buf_LRU_flush_or_remove_pages(): Add a parameter for specifying
the number of the first page to flush or remove (default 0).
trx_purge_initiate_truncate(): Remove the log checkpoints, the
extra logging, and some unnecessary crash points. Merge the code
from trx_undo_truncate_tablespace(). First, flush all to-be-discarded
pages (beyond the new end of the file), then trim the space->size
to make the page allocation deterministic. At the only remaining
crash injection point, flush the redo log, so that the recovery
can be tested.
