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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.
53 lines
2.1 KiB
C
53 lines
2.1 KiB
C
/*****************************************************************************
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Copyright (C) 2013, 2017, MariaDB Corporation. All Rights Reserved.
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*****************************************************************************/
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/******************************************************************//**
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@file include/fsp0pagecompress.h
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Helper functions for extracting/storing page compression and
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atomic writes information to file space.
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Created 11/12/2013 Jan Lindström jan.lindstrom@skysql.com
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***********************************************************************/
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#ifndef fsp0pagecompress_h
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#define fsp0pagecompress_h
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/**********************************************************************//**
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Reads the page compression level from the first page of a tablespace.
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@return page compression level, or 0 if uncompressed */
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UNIV_INTERN
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ulint
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fsp_header_get_compression_level(
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/*=============================*/
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const page_t* page); /*!< in: first page of a tablespace */
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/********************************************************************//**
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Extract the page compression level from tablespace flags.
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A tablespace has only one physical page compression level
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whether that page is compressed or not.
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@return page compression level of the file-per-table tablespace,
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or zero if the table is not compressed. */
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UNIV_INLINE
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ulint
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fsp_flags_get_page_compression_level(
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/*=================================*/
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ulint flags); /*!< in: tablespace flags */
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#include "fsp0pagecompress.ic"
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#endif
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