May 2010 - docs - lists.mariadb.org

Re: [Maria-docs] Upcoming MariaDB 5.1.47 release
by Kristian Nielsen 01 Jun '10

01 Jun '10

MariaDB 5.1.47 packages are now uploaded to hasky. I've also provided the packages to OurDelta, looks like we will get repositories for MariaDB working again for this release (yay!). - Kristian. Kristian Nielsen <knielsen(a)knielsen-hq.org> writes: > I've tagged the 5.1-release tree with mariadb-5.1.47 and started building > packages for MariaDB 5.1.47. > > The release should be out early next week as soon as Daniel has had time to > prepare release notes and mirrors have caought up with packages. > > Daniel: Some things for release notes that I remember, to supplement what you > obtain from bzr commit messages: > > - New XtraDB version (If you don't find the version number in bzr, ask me to > dig it up from my notes). > > - New PBXT version. > > - Fix dependency problem with Ubuntu 10.04 Lucid packages, and build against > full release (no longer alpha). > > - Fix Ubuntu issue when using libmyodbc with mariadb packages. > > Regards, Kristian.

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[Maria-docs] [Kristian Nielsen] Upcoming MariaDB 5.1.47 release
by Kristian Nielsen 30 May '10

30 May '10

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[Maria-docs] FYI - new MariaDB:Mirroring page on wiki
by Daniel Bartholomew 27 May '10

27 May '10

All, I've created a new MariaDB:Mirroring page on the wiki. It has generic instructions for those that want to volunteer to mirror MariaDB. http://askmonty.org/wiki/MariaDB:Mirroring Constructive corrections, clarifications, and comments are welcome. Thanks. -- Daniel Bartholomew Monty Program - http://askmonty.org

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Re: [Maria-docs] [Maria-developers] Segmented Key Cache - About section
by Daniel Bartholomew 19 May '10

19 May '10

On Mon, 17 May 2010 11:14:15 -0700 Igor Babaev <igor(a)askmonty.org> wrote: Daniel> The original sentence from the worklog reads: Daniel> So threads compete for this lock even in the case when they Daniel> have acquired shared locks for the file and pages they want Daniel> read from are in the key cache buffers. Igor> Ok ,I will help with the reading of the original statement adding Igor> missing words: Igor> Igor> So threads compete for this lock even in the case when Igor> they have acquired shared locks for the file Igor> and Igor> the pages they want to read from are in the key cache buffers. Thanks for the clarification! -- Daniel Bartholomew Monty Program - http://askmonty.org

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[Maria-docs] Segmented Key Cache - Syntax section
by Daniel Bartholomew 17 May '10

17 May '10

Hello everyone, Summarizing from my previous email: I'm working on the documentation for the Segmented Key Cache, one of the new features in MariaDB 5.2. My previous email was about the "About" section of the documentation. This email is about the "Syntax" section. For the syntax section, I see there is one new global variable defined for this feature and a new KEY_CACHES table in the information_schema database. Are there any other user-visible items which should be mentioned? Here is a first draft of the syntax section: ---------------------------------------------------------------------- == Segmented Key Cache Syntax == New global variable: key_cache_partitions, it sets the number of segments in a key cache. Valid values for this variable are whole numbers between 0 and 64. If the number of partitions is set to a number greater than 64 the number of partitions will be truncated to 64 and a warning will be issued. A value of '0' means the key cache is a regular (i.e. non-segmented) key cache. This is the default. Other global variables used when working with regular key caches also apply to segmented key caches: key_buffer_size, key_cache_age_threshold, key_cache_block_size, and key_cache_division_limit. See the MySQL manual for descriptions of these variables. http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html Statistics about the key cache can be found by looking at the KEY_CACHES table in the INFORMATION_SCHEMA database. Columns in this table are: * KEY_CACHE_NAME: The name of the key cache * PARTITIONS: total number of segments * PARTITION_NUMBER: segment number (set to NULL if a simple key cache) * FULL_SIZE: memory for cache buffers/auxiliary structures * BLOCK_SIZE: size of the blocks * USED_BLOCKS: number of currently used blocks * UNUSED_BLOCKS: number of currently unused blocks * DIRTY_BLOCKS: number of currently dirty blocks * READ_REQUESTS: number of read requests * READS: number of actual reads from files into buffers * WRITE_REQUESTS: number of write requests * WRITES: number of actual writes from buffers into files ---------------------------------------------------------------------- If there are any factual errors with the above, let me know. Improvements and suggestions are also welcome. Question for the developers: A key_cache_partitions value of '0' means the key cache will not be segmented, it will be a regular (or simple) key cache. A value of '1' means the key cache will be a segmented key cache with a single segment. Is there any benefit to having a "single-segment segmented key cache" compared to a regular "simple key cache" or are they practically the same thing? The key_cache_partitions variable also needs to be documented on the Server System Variables page (http://askmonty.org/wiki/Manual:Server_System_Variables). The entry will look something like this: ---------------------------------------------------------------------- * <code>key_cache_partitions</code> ** '''Description:''' The number of segments in a key cache. ** '''Commandline:''' <code>--key_cache_partitions=#</code> ** '''Scope:''' Global ** '''Dynamic:''' No ** '''Type:''' number ** '''Valid values:''' <code>0-64</code> ** '''Default value:''' <code>0</code> ''(non-segmented)'' * '''Introduced:''' MariaDB 5.2 ---------------------------------------------------------------------- Let me know if there is anything wrong with the above. My task now is to come up with some examples. I'll probably use the test cases for inspiration unless someone has an awesome segmented key cache example that they've been dying to share with me. :) Thanks. -- Daniel Bartholomew Monty Program - http://askmonty.org

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[Maria-docs] Segmented Key Cache - About section
by Daniel Bartholomew 13 May '10

13 May '10

Hello everyone, I'm working on the documentation for the Segmented Key Cache, one of the new features in MariaDB 5.2. The documentation page will have "about", "syntax", and "example" sections. I've based the "About" section on the High-Level Description from the worklog ( http://askmonty.org/worklog/Server-Sprint/?tid=85 ) and from the description in the mysys/mf_keycache.c file in the source. Here is my first draft. I've changed the wording a bit to help it flow better and I've changed "partition" to "segment" in keeping with the official name. ---------------------------------------------------------------------- == About Segmented Key Cache == A segmented key cache is a collection of structures for regular MyISAM key caches called key cache segments. Segmented key caches mitigate one of the major problem of the simple key cache: thread contention for key cache lock (mutex). With regular key caches, every call of a key cache interface function must acquire this lock. Threads compete for this lock even when the file and pages they have acquired shared locks for are in the key cache buffers. When working with a segmented key cache any key cache interface function that needs only one page has to acquire the key cache lock only for the segment the page is assigned to. This makes the chances for threads not having to compete for the same key cache lock better. Any page from a file can be placed into a buffer of only one segment. The number of the segment is calculated from the file number and the position of the page in the file, and it's always the same for the page. Pages are evenly distributed among segments. The idea and the original code of the segmented key cache was provided by Fredrik Nylander from Stardoll.com. The code was extensively reworked, improved, and eventually merged into MariaDB by Igor Babaev from Monty Program. ---------------------------------------------------------------------- If there are any factual errors with the above, let me know. Improvements and suggestions are also welcome. One thing I'm not happy with is this sentence: "Threads compete for this lock even when the file and pages they have acquired shared locks for are in the key cache buffers." The original sentence from the worklog reads: So threads compete for this lock even in the case when they have acquired shared locks for the file and pages they want read from are in the key cache buffers. ... which is very confusing to me. If anyone has a better or more accurate rewording, please send it my way. Also, there's a note in the source code (lines 5018-5023 of mysys/mf_keycache.c) which states: Unfortunately if we use a partitioned key cache with N partitions for B-tree indexes we can't say that the chances becomes N times less. The fact is that any index lookup operation requires reading from the root page that, for any index, is always ascribed to the same partition. To resolve this problem we should have employed more sophisticated mechanisms of working with root pages. Do any of you have any opinions on whether or not this should be mentioned somewhere in the documentation? The only issue I have with mentioning it is that if I do, the first question that comes to my mind is: "If it is not N-times less, how much less is it?" I don't have an answer to that question (and math isn't one of my strengths). Next up will be the "Syntax" section. Thanks. -- Daniel Bartholomew Monty Program - http://askmonty.org

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Re: [Maria-docs] new mysqlbinlog option in MariaDB 5.2
by Daniel Bartholomew 11 May '10

11 May '10

On Fri, 7 May 2010 14:56:24 +0400 Sergey Petrunya <psergey(a)askmonty.org> wrote: Sergey> Hi Daniel, Sergey> Sergey> Here it is at last: Sergey> Sergey> On Fri, Apr 02, 2010 at 04:44:22PM -0400, Daniel Bartholomew Sergey> wrote: Daniel> I'm preparing documentation on mysqlbinlog for the MariaDB Daniel> 5.2. reference manual. Daniel> Daniel> From looking at the 'mysqlbinlog --help' output and comparing Daniel> it to the output of the version in 5.1.44 it looks like the Daniel> only command-line option that was added was Daniel> '--rewrite-db=name' (unless I'm missing something). Were any Daniel> other options added to mysqlbinlog? Sergey> None that I know of. Daniel> From the worklog Daniel> ( http://askmonty.org/worklog/Server-Sprint/?tid=36 ), it Daniel> looks like you were the MP developer who worked on it. Let me Daniel> know if I should ask someone else. Sergey> Yes, it was me from MP side. Sergey> Sergey> The net result is as follows: mysqlbinlog got a new option, Sergey> Sergey> --rewrite-db='db_from->db_to' Sergey> Sergey> which is very similar to replication slave option Sergey> Sergey> --replicate-rewrite-db=”from->to” Sergey> Sergey> Everything that is said about replicate-rewrite-db here: Sergey> http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#optio… Sergey> applies to --rewrite-db. Sergey> To rephrase it: for both options the following holds: Sergey> Sergey> - for events that are binlogged as statements, rewriting the Sergey> database constitutes changing statement's default database from Sergey> db1 to db2. There is no statement analysis or rewrite of any Sergey> kind, that is, if one specifies "db1.tbl" in the statement Sergey> explicitly, that occurence won't be changed to "db2.tbl". Sergey> Sergey> - Row-based events are rewritten correctly. Sergey> Sergey> For both slave and mysqlbinlog, filtering applies after the Sergey> database rewrites have been performed. By filtering, I mean Sergey> - --replicate-[do|ignore]-xxx options for slave Sergey> - --database option for mysqlbinlog. Sergey> Sergey> See also http://askmonty.org/wiki/Scratch/ReplicationOption for Sergey> a 'map' of various relevant options. Sergey> Sergey> Please ask more questions if the above is unclear. Sergey> Thanks for the information! I've used it to update the mysqlbinlog page on the wiki: http://askmonty.org/wiki/Manual:Mysqlbinlog The part dealing with --rewrite-db is at the bottom of the page (it's the last row in the big mysqlbinlog options table). Let me know if there are any errors or if you think something more should be added. Thanks again! -- Daniel Bartholomew Monty Program - http://askmonty.org

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[Maria-docs] MariaDB Release Process
by Daniel Bartholomew 05 May '10

05 May '10

FYI: I just updated the Release Process page on the wiki. I removed some outdated information and added some new information (such as sending a note to maria-docs(a)lists.launchpad.net when a tree is ready for release instead of to docs(a)askmonty.org). http://askmonty.org/wiki/Release_Process Take a look if you are interested and let me know of any errors or omissions. Thanks. -- Daniel Bartholomew Monty Program - http://askmonty.org

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[Maria-docs] New Maria Docs list
by Daniel Bartholomew 05 May '10

05 May '10

All, I've created a new "Maria Docs" Launchpad team and mailing list for documentation-related discussions (including things like documentation for current and upcoming releases of MariaDB, planning and discussion of the askmonty.org knowledgebase, and so on). The group is open to everyone. https://launchpad.net/~maria-docs Thanks! -- Daniel Bartholomew Monty Program - http://askmonty.org

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