Starting with commit baf276e6d4 (MDEV-19229)
the parameter innodb_undo_tablespaces can be increased from its
previous default value 0 while allowing an upgrade from old databases.
We will change the default setting to innodb_undo_tablespaces=3
so that the space occupied by possible bursts of undo log records
can be reclaimed after SET GLOBAL innodb_undo_log_truncate=ON.
We will not enable innodb_undo_log_truncate by default, because it
causes some observable performance degradation.
Special thanks to Thirunarayanan Balathandayuthapani for diagnosing
and fixing a number of bugs related to this new default setting.
Tested by: Matthias Leich, Axel Schwenke, Vladislav Vaintroub
(with both values of innodb_undo_log_truncate)
This is a follow-up task to MDEV-12026, which introduced
innodb_checksum_algorithm=full_crc32 and a simpler page format.
MDEV-12026 did not enable full_crc32 for page_compressed tables,
which we will be doing now.
This is joint work with Thirunarayanan Balathandayuthapani.
For innodb_checksum_algorithm=full_crc32 we change the
page_compressed format as follows:
FIL_PAGE_TYPE: The most significant bit will be set to indicate
page_compressed format. The least significant bits will contain
the compressed page size, rounded up to a multiple of 256 bytes.
The checksum will be stored in the last 4 bytes of the page
(whether it is the full page or a page_compressed page whose
size is determined by FIL_PAGE_TYPE), covering all preceding
bytes of the page. If encryption is used, then the page will
be encrypted between compression and computing the checksum.
For page_compressed, FIL_PAGE_LSN will not be repeated at
the end of the page.
FSP_SPACE_FLAGS (already implemented as part of MDEV-12026):
We will store the innodb_compression_algorithm that may be used
to compress pages. Previously, the choice of algorithm was written
to each compressed data page separately, and one would be unable
to know in advance which compression algorithm(s) are used.
fil_space_t::full_crc32_page_compressed_len(): Determine if the
page_compressed algorithm of the tablespace needs to know the
exact length of the compressed data. If yes, we will reserve and
write an extra byte for this right before the checksum.
buf_page_is_compressed(): Determine if a page uses page_compressed
(in any innodb_checksum_algorithm).
fil_page_decompress(): Pass also fil_space_t::flags so that the
format can be determined.
buf_page_is_zeroes(): Check if a page is full of zero bytes.
buf_page_full_crc32_is_corrupted(): Renamed from
buf_encrypted_full_crc32_page_is_corrupted(). For full_crc32,
we always simply validate the checksum to the page contents,
while the physical page size is explicitly specified by an
unencrypted part of the page header.
buf_page_full_crc32_size(): Determine the size of a full_crc32 page.
buf_dblwr_check_page_lsn(): Make this a debug-only function, because
it involves potentially costly lookups of fil_space_t.
create_table_info_t::check_table_options(),
ha_innobase::check_if_supported_inplace_alter(): Do allow the creation
of SPATIAL INDEX with full_crc32 also when page_compressed is used.
commit_cache_norebuild(): Preserve the compression algorithm when
updating the page_compression_level.
dict_tf_to_fsp_flags(): Set the flags for page compression algorithm.
FIXME: Maybe there should be a table option page_compression_algorithm
and a session variable to back it?
MariaDB data-at-rest encryption (innodb_encrypt_tables)
had repurposed the same unused data field that was repurposed
in MySQL 5.7 (and MariaDB 10.2) for the Split Sequence Number (SSN)
field of SPATIAL INDEX. Because of this, MariaDB was unable to
support encryption on SPATIAL INDEX pages.
Furthermore, InnoDB page checksums skipped some bytes, and there
are multiple variations and checksum algorithms. By default,
InnoDB accepts all variations of all algorithms that ever existed.
This unnecessarily weakens the page checksums.
We hereby introduce two more innodb_checksum_algorithm variants
(full_crc32, strict_full_crc32) that are special in a way:
When either setting is active, newly created data files will
carry a flag (fil_space_t::full_crc32()) that indicates that
all pages of the file will use a full CRC-32C checksum over the
entire page contents (excluding the bytes where the checksum
is stored, at the very end of the page). Such files will always
use that checksum, no matter what the parameter
innodb_checksum_algorithm is assigned to.
For old files, the old checksum algorithms will continue to be
used. The value strict_full_crc32 will be equivalent to strict_crc32
and the value full_crc32 will be equivalent to crc32.
ROW_FORMAT=COMPRESSED tables will only use the old format.
These tables do not support new features, such as larger
innodb_page_size or instant ADD/DROP COLUMN. They may be
deprecated in the future. We do not want an unnecessary
file format change for them.
The new full_crc32() format also cleans up the MariaDB tablespace
flags. We will reserve flags to store the page_compressed
compression algorithm, and to store the compressed payload length,
so that checksum can be computed over the compressed (and
possibly encrypted) stream and can be validated without
decrypting or decompressing the page.
In the full_crc32 format, there no longer are separate before-encryption
and after-encryption checksums for pages. The single checksum is
computed on the page contents that is written to the file.
We do not make the new algorithm the default for two reasons.
First, MariaDB 10.4.2 was a beta release, and the default values
of parameters should not change after beta. Second, we did not
yet implement the full_crc32 format for page_compressed pages.
This will be fixed in MDEV-18644.
This is joint work with Marko Mäkelä.
The following INFORMATION_SCHEMA views were unnecessarily retrieving
the data from the SYS_TABLESPACES table instead of directly fetching
it from the fil_system cache:
information_schema.innodb_tablespaces_encryption
information_schema.innodb_tablespaces_scrubbing
InnoDB always loads all tablespace metadata into memory at startup
and never evicts it while the tablespace exists.
With this fix, accessing these views will be much faster and use less
memory, and include data about all tablespaces, including undo
tablespaces.
The view information_schema.innodb_sys_tablespaces will still reflect
the contents of the SYS_TABLESPACES table.
MDEV-13851 Always check table options in ALTER TABLE…ALGORITHM=INPLACE
In the merge of MySQL 5.7.9 to MariaDB 10.2.2, some code was included
that prevents ADD SPATIAL INDEX from being executed with ALGORITHM=INPLACE.
Also, the constant ADD_SPATIAL_INDEX was introduced as an alias
to ADD_INDEX. We will remove that alias now, and properly implement
the same ADD SPATIAL INDEX restrictions as MySQL 5.7 does:
1. table-rebuilding operations are not allowed if SPATIAL INDEX survive it
2. ALTER TABLE…ADD SPATIAL INDEX…LOCK=NONE is not allowed
ha_innobase::prepare_inplace_alter_table(): If the ALTER TABLE
requires actions within InnoDB, enforce the table options (MDEV-13851).
In this way, we will keep denying ADD SPATIAL INDEX for tables
that use encryption (MDEV-11974), even if ALGORITHM=INPLACE is used.
Encryption stores used key_version to
FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION (offset 26)
field. Spatial indexes store RTREE Split Sequence Number
(FIL_RTREE_SPLIT_SEQ_NUM) in the same field. Both values
can't be stored in same field. Thus, current encryption
implementation does not support encrypting spatial indexes.
fil_space_encrypt(): Do not encrypt page if page type is
FIL_PAGE_RTREE (this is required for background
encryption innodb-encrypt-tables=ON).
create_table_info_t::check_table_options() Do not allow creating
table with ENCRYPTED=YES if table contains spatial index.
