If crypt_block != NULL the entire object crypt_pfx should be
guaranteed to be initialized, including m_size, which will have been
initialized either in allocate_large(), either directly or via
allocate_trace().
This was done in, among other things:
- thd->db and thd->db_length
- TABLE_LIST tablename, db, alias and schema_name
- Audit plugin database name
- lex->db
- All db and table names in Alter_table_ctx
- st_select_lex db
Other things:
- Changed a lot of functions to take const LEX_CSTRING* as argument
for db, table_name and alias. See init_one_table() as an example.
- Changed some function arguments from LEX_CSTRING to const LEX_CSTRING
- Changed some lists from LEX_STRING to LEX_CSTRING
- threads_mysql.result changed because process list_db wasn't always
correctly updated
- New append_identifier() function that takes LEX_CSTRING* as arguments
- Added new element tmp_buff to Alter_table_ctx to separate temp name
handling from temporary space
- Ensure we store the length after my_casedn_str() of table/db names
- Removed not used version of rename_table_in_stat_tables()
- Changed Natural_join_column::table_name and db_name() to never return
NULL (used for print)
- thd->get_db() now returns db as a printable string (thd->db.str or "")
Only invoke set_versioned() on trx_id versioned tables.
dict_table_t::versioned_by_id(): New accessor, to determine if
a table is system versioned by transaction ID.
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.
Remove volatile modifier from waiters: it's not supposed for inter-thread
communication, use appropriate atomic operations instead.
Changed waiters to int32_t, my_atomic friendly type.
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.
Both bits DATA_VERSIONED will be set in prtype if the column
is system-versioned. The bits will be 0 for normal unversioned
columns. For the special columns identifying the logical start
and end times of versions, only one bit will be set:
DATA_VERS_START or DATA_VERS_END.
create_table_info_t::create_table_def(),
prepare_inplace_alter_table_dict(): Set prtype |= DATA_VERSIONED
for system-versioned columns.
dfield_t::is_version_historical_end(): Determine if a data tuple
field is_version_end() and contains a timestamp in the past
(not TRX_ID_MAX).
dtype_t, dict_col_t: Add the accessors
is_versioned(), is_version_start(), is_version_end().
trx_id_max_bytes[]: The bit pattern of TRX_ID_MAX, for use with
memcmp().
remove remnants of 10.0 bugfix, incorrectly merged into 10.2
Using col_names[i] was obviously, wrong, must've been col_names[ifield->col_no].
incorrect column name resulted in innodb having index unique_id2(id1),
while the server thought it's unique_id2(id4).
But col_names[ifield->col_no] is wrong too, because `table` has non-renamed
columns, so the correct column name is always dict_table_get_col_name(table, ifield->col_no)
Reverted incorrect changes done on MDEV-7367 and MDEV-9469. Fixes properly
also related bugs:
MDEV-13668: InnoDB unnecessarily rebuilds table when renaming a column and adding index
MDEV-9469: 'Incorrect key file' on ALTER TABLE
MDEV-9548: Alter table (renaming and adding index) fails with "Incorrect key file for table"
MDEV-10535: ALTER TABLE causes standalone/wsrep cluster crash
MDEV-13640: ALTER TABLE CHANGE and ADD INDEX on auto_increment column fails with "Incorrect key file for table..."
Root cause for all these bugs is the fact that MariaDB .frm file
can contain virtual columns but InnoDB dictionary does not and
previous fixes were incorrect or unnecessarily forced table
rebuilt. In index creation key_part->fieldnr can be bigger than
number of columns in InnoDB data dictionary. We need to skip not
stored fields when calculating correct column number for InnoDB
data dictionary.
dict_table_get_col_name_for_mysql
Remove
innobase_match_index_columns
Revert incorrect change done on MDEV-7367
innobase_need_rebuild
Remove unnecessary rebuild force when column is renamed.
innobase_create_index_field_def
Calculate InnoDB column number correctly and remove
unnecessary column name set.
innobase_create_index_def, innobase_create_key_defs
Remove unneeded fields parameter. Revert unneeded memset.
prepare_inplace_alter_table_dict
Remove unneeded col_names parameter
index_field_t
Remove unneeded col_name member.
row_merge_create_index
Remove unneeded col_names parameter and resolution.
Effected tests:
innodb-alter-table : Add test case for MDEV-13668
innodb-alter : Remove MDEV-13668, MDEV-9469 FIXMEs
and restore original tests
innodb-wl5980-alter : Remove MDEV-13668, MDEV-9469 FIXMEs
and restore original tests
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().
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.
This should also fix the MariaDB 10.2.2 bug
MDEV-13826 CREATE FULLTEXT INDEX on encrypted table fails.
MDEV-12634 FIXME: Modify innodb-index-online, innodb-table-online
so that they will write and read merge sort files. InnoDB 5.7
introduced some optimizations to avoid using the files for small tables.
Many collation test results have been adjusted for MDEV-10191.
Introduce innodb_encrypt_log.combinations and prove that
the encryption and decryption take place during both
online ADD INDEX (WL#5266) and online table-rebuilding ALTER (WL#6625).
…porary file
Fixed by removing writing key version to start of every block that
was encrypted. Instead we will use single key version from log_sys
crypt info.
After this MDEV also blocks writen to row log are encrypted and blocks
read from row log aren decrypted if encryption is configured for the
table.
innodb_status_variables[], struct srv_stats_t
Added status variables for merge block and row log block
encryption and decryption amounts.
Removed ROW_MERGE_RESERVE_SIZE define.
row_merge_fts_doc_tokenize
Remove ROW_MERGE_RESERVE_SIZE
row_log_t
Add index, crypt_tail, crypt_head to be used in case of
encryption.
row_log_online_op, row_log_table_close_func
Before writing a block encrypt it if encryption is enabled
row_log_table_apply_ops, row_log_apply_ops
After reading a block decrypt it if encryption is enabled
row_log_allocate
Allocate temporary buffers crypt_head and crypt_tail
if needed.
row_log_free
Free temporary buffers crypt_head and crypt_tail if they
exist.
row_merge_encrypt_buf, row_merge_decrypt_buf
Removed.
row_merge_buf_create, row_merge_buf_write
Remove ROW_MERGE_RESERVE_SIZE
row_merge_build_indexes
Allocate temporary buffer used in decryption and encryption
if needed.
log_tmp_blocks_crypt, log_tmp_block_encrypt, log_temp_block_decrypt
New functions used in block encryption and decryption
log_tmp_is_encrypted
New function to check is encryption enabled.
Added test case innodb-rowlog to force creating a row log and
verify that operations are done using introduced status
variables.
In online table-rebuilding ALTER TABLE (LOCK=NONE), virtual column values
are being written to the online_log. WL#8149 in MySQL 5.7 changed some
low-level functions that are also being used outside row0log.cc, causing
performance penalty to other code.
We revert those changes, and introduce separate functions for writing
the virtual column values.
The only functional change should be the one that is mentioned in
MDEV-13795: row_log_table_low_redundant() will no longer write
virtual column values along with old_pk, just like row_log_table_low().
As noted in MDEV-13795, some forms of table-rebuilding ALTER with
virtual columns is broken. At least DROP PRIMARY KEY, ADD PRIMARY KEY
is broken.
rec_get_converted_size_temp(), rec_convert_dtuple_to_temp():
Remove the parameter for passing virtual column values.
rec_get_converted_size_temp_v(), rec_convert_dtuple_to_temp_v():
New functions for appending virtual column values to the online_log.
rec_get_converted_size_comp_prefix_low(),
rec_convert_dtuple_to_rec_comp(): Remove the v_entry parameter,
and do not allow n_fields=0.
row_merge_read_clustered_index(): The row->fields[] could point
to a record in the clustered index page of the source table, or
to an old version of the record that was constructed in row_heap.
If the row->fields[] points to the clustered index page, then
we were modifying buffer pool data without holding appropriate
block->lock and without appropriate redo logging. The intention
was to modify a copy of the data, not the source file page,
because concurrent readers would still very much need the original
values of the DB_TRX_ID,DB_ROLL_PTR for their multi-versioning.
Either way, it is simplest to not write anything at all, and to
make row->fields[] point to the constant reset_trx_id.
innobase_rec_reset(): Remove. This function was introduced in the
InnoDB Plugin for MySQL 5.1, which later evolved into MySQL 5.5.
There used to be a bug that ADD UNIQUE INDEX would not always correctly
report the duplicate key value of the secondary index. This function
ensured that instead of reporting total garbage values, InnoDB
would report NULL.
It looks like the function was made unnecessary in MySQL 5.6.6 by
d143097eb1
The corresponding test was subsequently adjusted in
fde80cf49d
The ALTER TABLE tests were imported to MariaDB as part of MDEV-13625,
and these tests do pass with this change.
The unnecessary function did not do any harm before MDEV-11371 introduced
compressed columns.
One question remains: What if we needed to report a duplicate key value
for a compressed column? The simple answer is that the test
main.column_compression demonstrates that no indexes can be defined
on compressed columns.
After MDEV-12288 and MDEV-13536, the DB_TRX_ID of old clustered index
records for which no history is available should be reset to 0.
This caused crashes in online table-rebuilding ALTER, because the
row_log_table_apply() is built on the assumption that the PRIMARY KEY
together with DB_TRX_ID,DB_ROLL_PTR identifies the record.
Both when copying the old table and when writing log about changes to
the old table, we must map "old" DB_TRX_ID to 0. "old" here is simply
"older than the trx_id of the ALTER TABLE transaction", because
the MDL_EXCLUSIVE (and exclusive InnoDB table lock) in
ha_innobase::prepare_inplace_alter_table() forces any transactions
accessing the table to commit or rollback. So, we know that we can
safely reset any DB_TRX_ID in the table that is older than the
transaction ID of the ALTER TABLE, because the undo log history would be
lost in a table-rebuilding ALTER.
Note: After a table-rebuilding online ALTER TABLE, the rebuilt table
may end up containing some nonzero DB_TRX_ID columns. The apply logic
identifies the rows by the combination of PRIMARY KEY and DB_TRX_ID.
These nonzero DB_TRX_ID would necessarily refer to concurrent DML
operations that were started during ha_innobase::inplace_alter_table().
row_log_allocate(): Add a parameter for the ALTER TABLE transaction.
row_log_t::min_trx: The ALTER TABLE transaction ID.
trx_id_check(): A debug function to check that DB_TRX_ID makes sense
(is either 0 or bigger than the ALTER TABLE transaction ID).
reset_trx_id[]: The reset DB_TRX_ID,DB_ROLL_PTR columns.
row_log_table_delete(), row_log_table_get_pk(): Reset the
DB_TRX_ID,DB_ROLL_PTR when they precede the ALTER TABLE transaction.
row_log_table_apply_delete(), row_log_table_apply_update():
Assert trx_id_check().
row_merge_insert_index_tuples(): Remove the unused parameter trx_id.
row_merge_read_clustered_index(): In a table-rebuilding ALTER,
reset the DB_TRX_ID,DB_ROLL_PTR when they precede the ALTER TABLE
transaction. Assert trx_id_check() on clustered index records that
are being buffered.
Storage engine independent support for column compression.
TINYBLOB, BLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT,
VARCHAR and VARBINARY columns can be compressed.
New COMPRESSED column attribute added:
COMPRESSED[=<compression_method>]
System variables added:
column_compression_threshold
column_compression_zlib_level
column_compression_zlib_strategy
column_compression_zlib_wrap
Status variables added:
Column_compressions
Column_decompressions
Limitations:
- the only supported method currently is zlib
- CSV storage engine stores data uncompressed on-disk even if COMPRESSED
attribute is present
- it is not possible to create indexes over compressed columns.
If compiling a non DBUG binary with
-DDBUG_ASSERT_AS_PRINTF asserts will be
changed to printf + stack trace (of stack
trace are enabled).
- Changed #ifndef DBUG_OFF to
#ifdef DBUG_ASSERT_EXISTS
for those DBUG_OFF that was just used to enable
assert
- Assert checking that could greatly impact
performance where changed to DBUG_ASSERT_SLOW which
is not affected by DBUG_ASSERT_AS_PRINTF
- Added one extra option to my_print_stacktrace() to
get more silent in case of stack trace printing as
part of assert.
