3cdbcc69dd
The linear read-ahead, which is enabled by default by a nonzero default value of innodb_read_ahead_threshold=56, only works if index leaf pages or undo log pages have been allocated on adjacent page numbers. That is not always the case. After this change, the exact nonzero values of innodb_read_ahead_threshold matter only for the read-ahead of undo log pages. For the read-ahead of B-tree leaf pages when starting a read from an index, it only matters if innodb_read_ahead_threshold=0. buf_read_ahead_undo(): Renamed from buf_read_ahead_linear(). This function will no longer be invoked on any BLOB pages (for which FIL_PAGE_PREV and FIL_PAGE_NEXT were not initialized consistently) nor on any index pages. For index leaf pages, we will introduce buf_read_ahead_one() and buf_read_ahead_pages(). btr_cur_t::search_leaf(), btr_cur_t::open_leaf(): Implement read-ahead for up to 16 leaf-level B-tree pages. This logic is enabled by a nonzero value of innodb_read_ahead_threshold; the actual value will not matter here. buf_read_ahead_update(), buf_read_ahead_update_sql(): Some common code for updating counters. buf_read_ahead_one(): Read ahead one (sibling leaf) page. This logic cannot be disabled. buf_read_ahead_pages(): Read ahead B-tree index leaf pages. buf_read_ahead_random(): Split the function into two parts: one that determines which range of pages should be read, and another that actually initiates a read of the pages. buf_read_page_low(): Remove a bogus comment. btr_pcur_move_to_next_page(): Invoke buf_read_ahead_one() instead of buf_read_ahead_linear(). btr_pcur_move_backward_from_page(): Implement a fast path of trying to acquire a latch on the previous page without waiting, and invoke buf_read_ahead_one() on the preceding page, with the assumption that we may be accessing that page in the near future. btr_copy_blob_prefix(): Simplify the logic. On other than ROW_FORMAT=COMPRESSED BLOB pages, the FIL_PAGE_NEXT field is not meaningfully initialized. The FIL_PAGE_PREV field is not pointing to anything meaningful either. buf_read_ahead_linear() expects these to be set meaningfully. Only the non-default setting innodb_random_read_ahead=ON might be meaningful here. |
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| client | ||
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| debian | ||
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| extra | ||
| include | ||
| libmariadb@55abb32038 | ||
| libmysqld | ||
| libservices | ||
| man | ||
| mysql-test | ||
| mysys | ||
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| randgen/conf | ||
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| sql-bench | ||
| sql-common | ||
| storage | ||
| strings | ||
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| tpool | ||
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| wsrep-lib@e55f01ce1e | ||
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| BUILD-CMAKE | ||
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| config.h.cmake | ||
| configure.cmake | ||
| CONTRIBUTING.md | ||
| COPYING | ||
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| INSTALL-WIN-SOURCE | ||
| KNOWN_BUGS.txt | ||
| README.md | ||
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Code status:
ci.appveyor.com
MariaDB: The innovative open source database
MariaDB was designed as a drop-in replacement of MySQL(R) with more features, new storage engines, fewer bugs, and better performance.
MariaDB is brought to you by the MariaDB Foundation and the MariaDB Corporation. Please read the CREDITS file for details about the MariaDB Foundation, and who is developing MariaDB.
MariaDB is developed by many of the original developers of MySQL who now work for the MariaDB Corporation, the MariaDB Foundation and by many people in the community.
MySQL, which is the base of MariaDB, is a product and trademark of Oracle Corporation, Inc. For a list of developers and other contributors, see the Credits appendix. You can also run 'SHOW authors' to get a list of active contributors.
A description of the MariaDB project and a manual can be found at:
https://mariadb.com/kb/en/mariadb-vs-mysql-features/
https://mariadb.com/kb/en/mariadb-versus-mysql-compatibility/
https://mariadb.com/kb/en/new-and-old-releases/
Getting the code, building it and testing it
Refer to the following guide: https://mariadb.org/get-involved/getting-started-for-developers/get-code-build-test/ which outlines how to build the source code correctly and run the MariaDB testing framework, as well as which branch to target for your contributions.
Help
More help is available from the Maria Discuss mailing list https://lists.mariadb.org/postorius/lists/discuss.lists.mariadb.org/ and MariaDB's Zulip instance, https://mariadb.zulipchat.com/
Licensing
MariaDB is specifically available only under version 2 of the GNU General Public License (GPLv2). (I.e. Without the "any later version" clause.) This is inherited from MySQL. Please see the README file in the MySQL distribution for more information.
License information can be found in the COPYING file. Third party license information can be found in the THIRDPARTY file.
Bug Reports
Bug and/or error reports regarding MariaDB should be submitted at: https://jira.mariadb.org
For reporting security vulnerabilities see: https://mariadb.org/about/security-policy/
The code for MariaDB, including all revision history, can be found at: https://github.com/MariaDB/server