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Re: [Maria-developers] Active Directory authentication plugin - GSoC 2014
by Sergei Golubchik 05 Mar '14

05 Mar '14

Hi, Talina! On Feb 28, talinashrotriya(a)gmail.com wrote: > Hello Sir, > > My name is Talina, presently studying Computer Science from India. > > I am interested to work on the “Active Directory authentication plugin”project. I am good at C/C++ , MYSQL and also have good knowledge about Active directory. Could you suggest me a few links to get started with? > Eager to start work. > > Thanks! We don't have this project on the https://mariadb.com/kb/en/google-summer-of-code-2014/ anymore. I will add it back when we have a mentor for it. Regards, Sergei

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[Maria-developers] MariaDB & MySQL community event 3rd of April 2014 in Santa Clara
by Michael Widenius 05 Mar '14

05 Mar '14

Hi! I am happy to announce that the MariaDB Foundation is organising a MariaDB & MySQL community event in Santa Clara on Thursday the 3rd of April. The venue is the Hilton Santa Clara hotel, a short walk from the Percona Live 2014 event. You can find more information on my blog at: http://monty-says.blogspot.fi/2014/03/mariadb-mysql-community-event-2014-in… We already got some very interesting talks and speakers, but I would like to see even more talk proposals. It's ok to propose a talk that it's also hold at Percona Live. As this event is free, I expect a totally different group of attendees, so that should be fine! When we have got a nice list of proposed talks, we will post them here so that everyone has a chance of commenting of which talks should be accepted. (Sorry, but this time we don't have time to create a proper selection committee so we have to do this a bit rough) Personally I will talk about MariaDB 10.0, which should be declared stable by then. Hope to see many MariaDB developers and users in Santa Clara! You can sign up for the event and/or dinner at: http://www.eventbrite.com/e/mariadb-mysql-community-event-2014-tickets-1080… Regards, Monty PS: Feel free to discuss the event on this email list! We want to have as many as possible participating in making this the best possible MariaDB and MySQL event.

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[Maria-developers] regarding the project in gsoc 2014
by nitin goel 05 Mar '14

05 Mar '14

Sir/Ma'am, I would like to bring to your notice that i used 'mysql' to drop and create tables to understand project better but would like to know more specifications for the project 'create or replace, create if not exists, and drop if exists'. I have been working in C/C++ since 2010 and would like to learn more from you. Please also mention how to contact the mentor for the project and proceed further on project. Thanks Nitin Goel

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[Maria-developers] MariaDB slave_parallel_threads and MySQL slave_parallel_workers
by Rasmus Johansson 05 Mar '14

05 Mar '14

Hi, I received a question that I wanted to share here to get some insight on. MariaDB 10.0 has a global setting named "slave_parallel_threads" and MySQL 5.7 has the same parameter named "slave_parallel_workers". Should slave_parallel_workers be an alias to slave_parallel_threads in MariaDB 10.0 to be more compatible with MySQL? BR, Rasmus -- Rasmus Johansson, VP Engineering MariaDB | t: +358 50 499 9589 | Skype: ratzpo

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[Maria-developers] [GSoC] memcached priorities
by Tan Tran 04 Mar '14

04 Mar '14

Hi all, I'm looking to do my GSoC project with MariaDB, specifically the suggestion to "Port the InnoDB memcached interface to MariaDB" on the page https://mariadb.com/kb/en/google-summer-of-code-2014/ . But the project description links to a JIRA bug at https://mariadb.atlassian.net/browse/MDEV-4674 , where the author suggests that we support memcached through TCP/UDP instead, with no mention of the InnoDB plugin. I figure that the InnoDB plugin is more important, since it's a MySQL 5.6 feature, it's widespread in industry, and the lack of a memcache interface is one of only a handful X's for MariaDB on http://www.skysql.com/blogs/max-mether/mysql-56-vs-mariadb-100 . Additionally, even without TCP/UDP support, one could just code the memcache logic manually anyway, whereas the InnoDB integration is more sophisticated and feature-rich and would be a good selling point for SkySQL. So I'd like to start working on a proposal. Can any devs weigh in on which aspect of memcache is more desirable for MariaDB? If it sounds likes a good, straightforward GSoC project that nobody else has claimed yet? Thanks, Tan Tran

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Re: [Maria-developers] Rev 4006: MDEV-5674 - Performance: my_hash_sort_bin is called too often
by Sergei Golubchik 04 Mar '14

04 Mar '14

Hi, Sergey! On Feb 14, Sergey Vojtovich wrote: > At lp:maria/10.0 > > ------------------------------------------------------------ > revno: 4006 > revision-id: svoj(a)mariadb.org-20140214122541-tenvcllk760deai8 > parent: svoj(a)mariadb.org-20140213071355-psk0jpsarx2u7myc > committer: Sergey Vojtovich <svoj(a)mariadb.org> > branch nick: 10.0 > timestamp: Fri 2014-02-14 16:25:41 +0400 > message: > MDEV-5674 - Performance: my_hash_sort_bin is called too often > > - reduced number of my_hash_sort_bin() calls from 4 to 2 per query. > Let MDL subsystem use pre-calculated hash value for hash > inserts and deletes. Is this necessary? One of the reasons why I didn't review this your first patch, because I believed that the second one obsoletes it. Why do you need my_hash_insert_using_hash_value() when you achieve the same effect with your calc_hash callback in the second patch? > - reduced number of memory accesses done by my_hash_sort_bin() I'd expect the compiler to handle it automatically, but feel free to change it, if it doesn't. Regards, Sergei

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Re: [Maria-developers] MDEV-5674 - Performance: my_hash_sort_bin is called too often
by Sergei Golubchik 04 Mar '14

04 Mar '14

Hi, Sergey! On Feb 20, Sergey Vojtovich wrote: > At lp:maria/10.0 > > ------------------------------------------------------------ > revno: 4007 > revision-id: svoj(a)mariadb.org-20140220072533-ko14y1714ouvd2f7 > parent: svoj(a)mariadb.org-20140214122541-tenvcllk760deai8 > committer: Sergey Vojtovich <svoj(a)mariadb.org> > branch nick: 10.0 > timestamp: Thu 2014-02-20 11:25:33 +0400 > message: > MDEV-5674 - Performance: my_hash_sort_bin is called too often It's MDEV-5675, not MDEV-5674 > Reuse MDL hash value in table cache: > - MDL namespace is excluded from hash value calculation, so that > hash value can be used by table cache as is > - hash value for MDL is calculated as resulting hash value + MDL > namespace > - extended hash implementation to accept user defined hash function This looks ok. I have a couple of comments, but they are mostly a question of taste. Up to you, you can push as is too. > === modified file 'sql/mdl.cc' > --- a/sql/mdl.cc 2014-02-14 12:25:41 +0000 > +++ b/sql/mdl.cc 2014-02-20 07:25:33 +0000 > @@ -760,13 +760,22 @@ void MDL_map::init() > } > > > +my_hash_value_type mdl_hash_function(const CHARSET_INFO *cs, > + const uchar *key, size_t length) > +{ > + return *((my_hash_value_type*) (key - offsetof(MDL_key, m_ptr) + > + offsetof(MDL_key, m_hash_value))) + > + key[0]; I'd prefer to avoid pointer and offset juggling. Because you use a custom hash function anyway, you can directly pass MDL_key as your "key", then here you can use ((MDL_key*)key)->hash_value() > +} > + > /** Initialize the partition in the container with all MDL locks. */ > > === modified file 'sql/mdl.h' > --- a/sql/mdl.h 2014-02-14 12:25:41 +0000 > +++ b/sql/mdl.h 2014-02-20 07:25:33 +0000 > @@ -397,7 +396,11 @@ class MDL_key > { > return & m_namespace_to_wait_state_name[(int)mdl_namespace()]; > } > - ulong hash_value() const > + my_hash_value_type hash_value() const > + { > + return m_hash_value + m_ptr[0]; I'm not sure it's a good idea, + is not a very good hash function :) On the other hand, I don't see anything immediately wrong with it in this particular case. Ok, let it be. Anyway, could you please use mdl_namespace() instead of m_ptr[0] where possible? > @@ -405,12 +408,14 @@ class MDL_key > private: > MDL_key(const MDL_key &); /* not implemented */ > MDL_key &operator=(const MDL_key &); /* not implemented */ > + friend my_hash_value_type mdl_hash_function(const CHARSET_INFO *, > + const uchar *, size_t); You probably wouldn't need this friend, if you'd change mdl_hash_function() to use MDL_key::hash_value() Regards, Sergei

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[Maria-developers] Suggestion ,a new member
by anupama vijjapu 04 Mar '14

04 Mar '14

Hello fellow developers, I joined MariaDB community today and need few suggestions/projects/bugs that i can work on. I do not have any knowledge of MariaDB source, but I will start looking into it now. I have hands on experience in C/C++/Java/Python and MySQL Database. Any suggestions/recommendation are highly appreciated.

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Re: [Maria-developers] Rev 4029: MDEV-4856 SQL_ERROR_LOG shows 1146 errors which didnt appear in mysql client
by Sergei Golubchik 03 Mar '14

03 Mar '14

Hi, Holyfoot! On Jan 31, holyfoot(a)askmonty.org wrote: > revno: 4029 > revision-id: holyfoot(a)askmonty.org-20140131103303-1rx7ielo83f8iahe > parent: holyfoot(a)askmonty.org-20140124020722-dd5twtwlcc8o1xiy > committer: Alexey Botchkov <holyfoot(a)askmonty.org> > branch nick: mdev-4856 > timestamp: Fri 2014-01-31 14:33:03 +0400 > message: > MDEV-4856 SQL_ERROR_LOG shows 1146 errors which didnt appear in mysql client. > The fill_schema_table() function used to call get_table_share() for > a table name in WHERE then clear the error list. That way plugins > receive the superfluous error notification if it happens in it. Also > the problem was that error handler didn't prevent the suppressed > error message from logging anyway as the logging happens in > THD::raise_condition before the handler call. > Fixed by adding the No_table_error_handler before the call. > raise_condition() also fixed. > === modified file 'sql/sql_class.cc' > --- a/sql/sql_class.cc 2014-01-23 18:21:02 +0000 > +++ b/sql/sql_class.cc 2014-01-31 10:33:03 +0000 > @@ -1145,7 +1145,6 @@ MYSQL_ERROR* THD::raise_condition(uint s > got_warning= 1; > break; > case MYSQL_ERROR::WARN_LEVEL_ERROR: > - mysql_audit_general(this, MYSQL_AUDIT_GENERAL_ERROR, sql_errno, msg); > break; > default: > DBUG_ASSERT(FALSE); > @@ -1156,6 +1155,8 @@ MYSQL_ERROR* THD::raise_condition(uint s > > if (level == MYSQL_ERROR::WARN_LEVEL_ERROR) > { > + mysql_audit_general(this, MYSQL_AUDIT_GENERAL_ERROR, sql_errno, msg); > + This is good. > === modified file 'sql/sql_show.cc' > --- a/sql/sql_show.cc 2013-11-19 12:16:25 +0000 > +++ b/sql/sql_show.cc 2014-01-31 10:33:03 +0000 > @@ -4199,8 +4199,13 @@ static int fill_schema_table_from_frm(TH > key_length= create_table_def_key(thd, key, &table_list, 0); > hash_value= my_calc_hash(&table_def_cache, (uchar*) key, key_length); > mysql_mutex_lock(&LOCK_open); > - share= get_table_share(thd, &table_list, key, > - key_length, OPEN_VIEW, &not_used, hash_value); > + { > + No_such_table_error_handler no_such_table_handler; > + thd->push_internal_handler(&no_such_table_handler); > + share= get_table_share(thd, &table_list, key, > + key_length, OPEN_VIEW, &not_used, hash_value); > + thd->pop_internal_handler(); > + } But I don't understand that. Do you mean, old code did *not* suppress errors here? How could selects from I_S tables work without it? Regards, Sergei

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[Maria-developers] New member, Need suggestion
by Neil Shah 03 Mar '14

03 Mar '14

Hello fellow developers, I joined MariaDB community today and need few suggestions/projects/bugs that i can work on. I do not have any knowledge of MariaDB source, but I will start looking into it now. I have hands on experience in C/C++/Java/Python and MySQL Database. Any suggestions/recommendation are highly appreciated. -- Thanks & Regards Neil Shah

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[Maria-developers] slave_ddl_exec_mode and incompatible change in MariaDB 10.0.8
by Pavel Ivanov 03 Mar '14

03 Mar '14

Hi, I've discovered a change in MariaDB 10.0.8 that I don't quite understand motivation for and which looks really surprising to me. So I would appreciate if you could tell me what's the motivation and why you think it's appropriate to do that. The change in question is http://bazaar.launchpad.net/~maria-captains/maria/10.0/revision/3961.1.7. I see several issues with it: 1. It introduces a pretty significant variable slave_ddl_exec_mode which wasn't announced in the Release Notes. 2. The default variable value was set to IDEMPOTENT which changes MariaDB slave behavior in an incompatible way. Not everyone will want to have this variable set to IDEMPOTENT (I'd actually argue that no one should set it to IDEMPOTENT), but without any mentioning of this variable in the Release Notes people basically have the only chance to get knowledge about this change (let me stress out: _incompatible_ change) from production incidents or from accidental code inspection. 3. When slave_ddl_exec_mode is set to IDEMPOTENT every "DROP TABLE" event in master's binlog is converted into "DROP TABLE IF EXISTS" in slave's binlog, which I believe is a major no-no for replication. Binlogs on master and slave should be identical, otherwise after failover even if one would set slave_ddl_exec_mode = STRICT it will still execute "DROP TABLE IF EXISTS" because new master has that in binlogs. 4. Why this change introduces OPTION_GTID_BEGIN in the code? Why OPTION_BEGIN wasn't enough? From reading the code the only thing I understand is that with broken binlogs and sequence of events "GTID BEGIN; CREATE TABLE; CREATE TABLE" MariaDB will try to execute both CREATE TABLE statements in the same transaction without auto-committing at the end. This sounds pretty crazy to me. And given the fact that in normal situation such sequence of events on the master is not possible it seems that existence of both OPTION_BEGIN and OPTION_GTID_BEGIN only introduces confusion (MariaDB have GTID always on, right? So it should always execute GTID_BEGIN and never BEGIN without GTID, right?). So what is your word on this? Can you at least set default value for slave_ddl_exec_mode to STRICT so that slave behavior didn't change with the version upgrade? Thank you, Pavel

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Re: [Maria-developers] MariaDB Master Replication To MySQL
by Kristian Nielsen 03 Mar '14

03 Mar '14

> In this particular case, we have someone that wants to use MariaDB 10.0 master with a MySQL 5.6 slave. But they are running into a problem with GTID. Generally, the recommended setup is to only replicate from old version on master to new (or same) version on slave. Replicating from new master to old slave in general is hard to support 100%, as there may be eg. new SQL syntax on the master that is impossible for the old version slave to execute. That being said, the intention is that replication from new master to old slave (like MariaDB 10.0 -> MySQL 5.6) should work in most reasonable cases. So this sounds like a bug which might be worth filing. > 2.) Is it possible to disable GTID in 10.0? It seems like it would break a few other things like parallel replication, but they're only running MariaDB on the master. GTID is disabled automatically when the slave does not support it. The code rewrites the binlog stream on the fly to remove events that are not supported on the old slave, and replace them with something appropriate for that slave version. Does the same problem occur when replicating from MariaDB 10.0 master to MariaDB 5.5 slave? What about when replicating from MySQL 5.5 master to MySQL 5.6 slave? - Kristian.

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Re: [Maria-developers] MDEV-5755 - Scalability: let LOCK_open and THR_LOCK::mutex be normal mutexes
by Sergei Golubchik 03 Mar '14

03 Mar '14

Hi, Sergey! On Feb 27, Sergey Vojtovich wrote: > At lp:maria/10.0 > > ------------------------------------------------------------ > revno: 4011 > revision-id: svoj(a)mariadb.org-20140227141521-fgj5b0h3qbijyojh > parent: svoj(a)mariadb.org-20140220072533-l3au3y7mrsyclfpb > committer: Sergey Vojtovich <svoj(a)mariadb.org> > branch nick: 10.0 > timestamp: Thu 2014-02-27 18:15:21 +0400 > message: > MDEV-5755 - Scalability: let LOCK_open and THR_LOCK::mutex be normal mutexes > > Normal mutexes scale better than adaptive at high thread count. > At low thread count they behave similarly. To summarize Axel results: at low concurency normal can be ~1% slower. at high concurrency r/o - normal are up to 25% faster. at high concurrency r/w - normal are up to 10% slower. That last result bothers me a litte. Regards, Sergei

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[Maria-developers] MDEV-5081 - Simple performance improvement for MariaDB
by Sergey Vojtovich 28 Feb '14

28 Feb '14

Hi Sergei, do you know if we ship any binaries with fast mutex (-DMY_PTHREAD_FASTMUTEX) enabled or officially suggest it? What was it's intention and what loads it was supposed to make faster? I'm trying to understand if fastmutex is worth fixing. It looks like duplication of PTHREAD_MUTEX_ADAPTIVE_NP, so we have double spinning when they're enabled. According to my recent benchmarks it shown worst performance. Thanks, Sergey

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[Maria-developers] Keystone authentication plugin GSoc 14
by Abhishek Solanki 28 Feb '14

28 Feb '14

Hello MariaDB members , I am interested to work on "Keystone authentication plugin" project , i have a good knowledge of C/C++ and OpenStack. So can anyone help me how to get started with this project, so that i cold dig something before applying for this project. -- Thanks, Abhishek

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[Maria-developers] Debian build / multi-architecture related bugs filed
by Otto Kekäläinen 27 Feb '14

27 Feb '14

Hello! The Debian build status can be seen at https://buildd.debian.org/status/package.php?p=mariadb-5.5 (and for MySQL at https://buildd.debian.org/status/package.php?p=mysql-5.5) The sparc build issue already got solved but for the others I filed the following bugs (as each failure seems to have different cause): https://mariadb.atlassian.net/browse/MDEV-5708 https://mariadb.atlassian.net/browse/MDEV-5707 https://mariadb.atlassian.net/browse/MDEV-5706 Could somebody please look into these? I assume that some of them might be easy if MySQL already has them solved, then all that needs to be done is to copy a patch from MySQL upstream or from MySQL patches in Debian (see http://anonscm.debian.org/gitweb/?p=pkg-mysql/mysql-5.5.git;a=tree;f=debian…) (MariaDB Debian builds are pulled from http://anonscm.debian.org/gitweb/?p=pkg-mysql/mariadb-5.5.git and mirrored at https://github.com/ottok/mariadb-5.5) Also, here are two QA issues that are related. I am not sure what to do with them: http://qa.debian.org/bls/packages/m/mariadb-5.5.html

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[Maria-developers] Problem with debug_sync, THD::enter_cond(), and kill ...
by Kristian Nielsen 26 Feb '14

26 Feb '14

I got a crash in my parallel replication test case, and this one turned out to be caused by a fundamental problem in debug_sync. I am not sure how to solve it, so I wanted to explain the issue in case others have some ideas. The crash happens in THD::awake() when a thread is killed: mysql_mutex_lock(&mysys_var->mutex); ... int ret= mysql_mutex_trylock(mysys_var->current_mutex); mysql_cond_broadcast(mysys_var->current_cond); if (!ret) mysql_mutex_unlock(mysys_var->current_mutex); The problem is that mysys_var->current_mutex changed between the trylock() and the unlock(), so we unlock a different mutex than the one we locked - ouch! The mutex changed because of this code in debug_sync.cc: if (thd->mysys_var) { old_mutex= thd->mysys_var->current_mutex; old_cond= thd->mysys_var->current_cond; thd->mysys_var->current_mutex= &debug_sync_global.ds_mutex; thd->mysys_var->current_cond= &debug_sync_global.ds_cond; } There is no mutex protection here. So this means that it is not safe to use debug_sync inside enter_cond()/exit_cond() if kill will be used on the thread at that point. Since I have a lot of tests for parallel replication where I test exactly for correct error handling when killing threads at various points in the parallel processing, it is not too surprising that I would eventually be hit by this :) I am going to avoid using debug_sync inside enter_cond()/exit_cond() for now. But any ideas for how to solve this properly? This is particularly nasty to be hit by, as it is not at all obvious that this use of debug_sync should be a problem. And it is not exactly easy to guess from the failure what the real problem is - assuming one can even reproduce the failure, the window of opportunity in the race is after all rather quite small. - Kristian.

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[Maria-developers] How handle_rpl_parallel_thread rollback partial transaction when STOP SLAVE In parallel replication
by nanyi607rao 26 Feb '14

26 Feb '14

hi Kristian, I have a quesion about parallel replication. In handle_rpl_parallel_thread(), a worker thread has got a whole transaction events, but it only apply partial events. this thread wouldl skip left events when do STOP SLAVE(is that rigth?) ,because sql_worker_killed() return true. but it seems that partial transaction won't be rollbacked for wait_for_prior_commit() always return false. do me wrong? or how would it rollback that partial transaction. 2014-02-25 nanyi607rao

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[Maria-developers] GSOC 2014 participation
by Suyash Loiwal 26 Feb '14

26 Feb '14

Hello I am Suyash Loiwal from India, currently pursuing my B.Tech from Manipal institute of Technology, Manipal. I would like to take a project under your organization. Can someone please guide me how to start? Thanks Suyash

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[Maria-developers] MDEV-4309: Review for 201402181003_sanja_copy_calls_patch.diff
by Sergey Petrunia 25 Feb '14

25 Feb '14

Hi Sanja, My input for 201402181003_sanja_copy_calls_patch.diff: * memcpy_field_possible() should have a function comment mentioning that it checks whether memcpy_field_value() can be used. * field_conv_incompatible() should have a function comment mentioning that it is a function that is used instead of field_conv() when we know in advance that memcpy_field_possible(...)==false. Ok to push after this is addressed. BR Sergei -- Sergei Petrunia, Software Developer MariaDB | Skype: sergefp | Blog: http://s.petrunia.net/blog

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[Maria-developers] MariaDB 5.5.36 stable and MariaDB Galera 10.0.7 alpha release prep
by Daniel Bartholomew 25 Feb '14

25 Feb '14

All, I've completed most of the prep work for the MariaDB 5.5.36 (stable) and MariaDB Galera Cluster 10.0.7 (alpha) releases. Current plan is to activate and announce these releases together on Monday, 24 Feb before noon US Eastern Time (barring any last-minute issues). Draft changelogs and release notes are at the following locations: MariaDB 5.5.36 stable - https://mariadb.com/kb/en/mariadb-5536-release-notes/ - https://mariadb.com/kb/en/mariadb-5536-changelog/ MariaDB Galera Cluster 10.0.7 alpha - https://mariadb.com/kb/en/mariadb-galera-cluster-1007-release-notes/ - https://mariadb.com/kb/en/mariadb-galera-cluster-1007-changelog/ Please let me know ASAP of any additions, changes, typos, etc.... The 5.5.36 release notes in particular are very generic at the moment, so I'm very interested in additions to that page (please jump in and add!). The files for these releases are gradually making their way to MariaDB mirrors world wide. The primary mirror has them now if you want to get a jump on the competition: http://ftp.osuosl.org/pub/mariadb/mariadb-galera-10.0.7 http://ftp.osuosl.org/pub/mariadb/mariadb-5.5.36 Obilgatory note #1: The plan is for these files to be the officially released files without any changes, but that may change if something unexpected comes up (and such things have happened in the past). For those that would like to test the MariaDB Galera Cluster 10.0.7-alpha yum and apt repositories prior to the actual release, because that's just how you roll, the following config entries should get you going (you'll need to copy/paste/edit for whatever distro you are actually using/testing/playing-around-with): # - - Ubuntu - - - - - - - - - - - - - - - - # MariaDB 10.0.8 Ubuntu test mariadb.list w/MGC 10.0.7-alpha deb http://ftp.osuosl.org/pub/mariadb/mariadb-10.0.8/repo/ubuntu saucy main # - - Debian - - - - - - - - - - - - - - - - - # MariaDB 10.0.8 Debian test mariadb.list w/MGC 10.0.7-alpha deb http://ftp.osuosl.org/pub/mariadb/mariadb-10.0.8/repo/debian wheezy main # - - Red Hat - - - - - - - - - - - - - - - - # MariaDB 10.0.8 RedHat MariaDB-test.repo w/ MGC 10.0.7-alpha [mariadb] name = MariaDB baseurl = http://yum.mariadb.org/10.0.8-upd/rhel6-amd64 gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB gpgcheck=1 # - - Fedora - - - - - - - - - - - - - - - - - # MariaDB 10.0.8 Fedora MariaDB-test.repo w/ MGC 10.0.7-alpha [mariadb] name = MariaDB baseurl = http://yum.mariadb.org/10.0.8-upd/fedora20-amd64 gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB gpgcheck=1 Obligatory note #2: These test alpha repos, if you use them, should be switched to the official ones (as produced by the repository configuration generator) after the release is officially out. Obligatory disclaimer #1: These test alpha repos are _completely_ untested. They may not work at all. Obligatory disclaimer #2: MariaDB Galera Cluster 10.0.7 is an ALPHA release. You have been warned. You're on your own. Good luck and Godspeed. :) Thanks. -- Daniel Bartholomew MariaDB

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[Maria-developers] MySQL Optimizer Trace Questions
by Christian Rober 25 Feb '14

25 Feb '14

Hello All, I work for TokuTek as a Storage Engine developer and I have been using the, relatively, new optimizer trace functionality. I have found the results very helpful when combined with analyzing the source code, but there a few questions I want to ask. Here is some output from the trace for a recent SELECT query on an InnoDB table: At the end of the trace, it shows the index chosen by, what I presume, is the optimizer: ... "considered_execution_plans": [ { "plan_prefix": [], "table": "`reports` `a`", "best_access_path": { "considered_access_paths": [ { "access_type": "ref", "index": "reports_group_id", "rows": 1.55e6, "cost": 411057, "chosen": true }, ... ] }, "cost_for_plan": 411057, "rows_for_plan": 1.55e6, "chosen": true } ] }, ... Here are the cost results for some rejected alternative indexes, (note: the row count for two of them is similar to the chosen index): ... "analyzing_range_alternatives": { "range_scan_alternatives" ... "rows": 2377102, "cost": 2.81e6, ... "rows": 1554164, "cost": 1.84e6, ... "rows": 2346664, "cost": 2.78e6, ... "rows": 1554164, "cost": 1.84e6, ... Here is the cost analysis for a table scan, from the beginning of the trace (still not as good as the above chosen index, but close on cost): ... "table": "`reports` `a`", "range_analysis": { "table_scan": { "rows": 3108329, "cost": 655076 }, ... Related to the fact that the table scan analysis is dominated by the large row count, and probably rejected as a valid plan compared to the chosen index for that very reason: 1. How is the row count more than merely informational to the optimizer? I had the impression the row count did not directly contribute to the optimizer's decision as much as the estimated cost, or that the row count was already accounted for/factored into in the final cost measurement. 2. Related to that question, what is cost exactly? Is there a unit of measurement (ex: Time, Disk Seeks, etc.)? 3. Is cost more important than row count or equally important? 4. What is the genesis of the cost variable displayed in the trace? I assume it is just a guess on the respective storage engine's part of how expensive (in terms of disk access, processing, time, etc.) getting the rows will be for the query. thanks in advance, Christian

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[Maria-developers] We are participating in Google Summer of Code 2014
by Colin Charles 25 Feb '14

25 Feb '14

Hi, It is with great pleasure that I can inform you that we have been accepted as an organisation to participate in Google Summer of Code 2014! It would be great to see more ideas pop up here: https://mariadb.com/kb/en/google-summer-of-code-2014/ More mentors are always wanted! I presume we will see a lot more student discussions here as well. If you have any questions that aren't answered on the lists, please send me a personal note Here's to more features & contributors in 2014. cheers, -colin -- Colin Charles, Chief Evangelist MariaDB | t: +6-012-204-3201 | Skype: colincharles

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[Maria-developers] MariaDB C-API and specific P_S tables
by Peter Laursen 24 Feb '14

24 Feb '14

THis is probably a question that Gerog Richter (or possibly Wlad) could reply to. I came across this bug report: http://bugs.mysql.com/bug.php?id=71801 .. files by former MySQL/Sun/Oracle supporter Veleriuy Kravtchuk We have a 64 bit C-application compiled with MariaDB C-API (on and for Windows 64 bit). I connect to MySQL 5.6.15 and execute SELECT * FROM `session_connect_attrs`; /* PROCESSLIST_ID ATTR_NAME ATTR_VALUE ORDINAL_POSITION -------------- --------------- ---------- ------------------ 2 _os Windows 0 2 _client_name libmariadb 1 2 _pid 5012 2 2 _thread 4640 3 2 _platform x86 4 2 _client_version 1.1.2 5 */ With the MySQL CLI 5.6.15, you will get /* PROCESSLIST_ID ATTR_NAME ATTR_VALUE ORDINAL_POSITION -------------- --------------- ---------- ------------------ 4 _os Win64 0 4 _client_name libmysql 1 4 _pid 4888 2 4 _thread 4320 3 4 _platform x86_64 4 4 program_name mysql 5 4 _client_version 5.6.15 6 */ The differences I notice are * Our application populates P_S with "Windows" - not "Win64" as the 5.6.15 CLI * Our application populates 'P_S with "x86" and not "x86_64". * Our application does not populate P_S with a "program_name". But it has a name of course! MySQL 5.6 docs at http://dev.mysql.com/doc/refman/5.6/en/performance-schema-connection-attrib… (as far as I can understand) that the client should use mysql_options() and mysql_options4() C API functions to populate P_S with all information. I have two questions: 1) Will the first 2 differences listed require a patch in our code or in libmariadb? 2) Obviosuly the lacking program name in the P_S tables is something that we will neeed to take care of ourselves. However I think that mysql_options4() was added in MySQL 5.6 and the MariaDB API does not supprot it currently (it is targeted to be compatible with Oracle 5.5 API, I think). And to populate the program name we may need to use mysql_options4(). Am I right?

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[Maria-developers] Using MariaDB SQL for other storage engine
by Amith Nagarajappa 24 Feb '14

24 Feb '14

Hello, I am a database guy and want to plug mariaDB sql engine for other storage engine. If I want to plugin a storage engine with mariadb to use mariadb's SQL should i use handler interface in the storage/examples directory. I am not sure how to start with this interface implementation for MariaDB. Any help or docs or weblink on this would be helpful. Thanks and Regards, Amith

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