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[Maria-developers] History of table changes
by Roberto Spadim 22 May '13

22 May '13

Hi guys, i was looking git and i don't know if there's something similar to mariadb alter table command could we develop something like git for create database,alter tables, create table, drop table, drop database? a log that could be useful to update databases table definition and read changes done and 'commits' done by dba or developer or a tool to read my table and read remote table and show the create command to make they in sync (ok here history is lost) thanks guys -- Roberto Spadim

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[Maria-developers] unexpected "Duplicate entry" error
by Kazuhiko Shiozaki 21 May '13

21 May '13

Hello, We sometimes (not always, not often but sometimes) have unexpected "Duplicate entry" error on the following table and with the following query : * table CREATE TABLE `category` ( `uid` bigint(20) unsigned NOT NULL, `category_uid` bigint(20) unsigned NOT NULL DEFAULT '0', `base_category_uid` bigint(20) unsigned NOT NULL DEFAULT '0', `category_strict_membership` tinyint(1) NOT NULL DEFAULT '0', PRIMARY KEY (`uid`,`category_uid`,`base_category_uid`,`category_strict_membership`), KEY `Membership` (`category_uid`,`base_category_uid`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci * query BEGIN; (some queries for other tables) DELETE FROM category WHERE uid=14026268; INSERT INTO category VALUES (14026268, 3131502, 2074, 1),(14026268, 2992, 2992, 0),(14026268, 3133077, 191, 1),(14026268, 1212264, 2992, 1); (some queries for other tables) COMMIT; * error Duplicate entry '14026268-3131502-2074-1' for key 'PRIMARY' But this duplicate entry error should not happen because DELETE is called in the same transaction, even if similar queries are sent from another connection at the same time. We confirmed that this kind of issue happens on the following environments using MySQL_python-1.2.3 : * MariaDB 5.5.25, XtraDB * MariaDB 5.5.29, XtraDB * MariaDB 5.5.29, InnoDB plugin Since it happens SOMETIMES, I cannot reproduce this issue by small query. Do you have any idea so that we can investigate this issue further ? Thanks in advance ! -- Kazuhiko Shiozaki Nexedi: Consulting and Development of Free / Open Source Software http://www.nexedi.com/ ERP5: Full Featured High End Open Source ERP http://www.erp5.com/

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Re: [Maria-developers] MariaDB and MySQL replication
by Kristian Nielsen 21 May '13

21 May '13

Jan Lindström <jplindst(a)mariadb.org> writes: > My question is how compatible replication between > > 1) MySQL (master) -> MariaDB (slave) > 2) MariaDB (master) -> MySQL (slave) In general, it should work, though there are some limitations. It also depends on versions. I always try to make MariaDB (master) -> MySQL (slave) work. For example, when new binlog events are introduced to MariaDB, the MariaDB master will not send them to slaves that do not understand the new events (whether MySQL slave, or older version of MariaDB), it will replace them with something compatible. This is not the best tested part of the code though, so there may be bugs. MySQL (master) -> MariaDB (slave) generally has limitations. This is the same as MySQL (high version master) -> MySQL (low version master). This is due to the MySQL replication teams approach, where you need to disable new features on the master for things to work with old slaves. For example, MySQL 5.6 (master) -> MySQL 5.5 (slave) does not work out-of-the box, so MariaDB 5.5 slave is the same. Generally, when incompatibilities are introduced in new MySQL versions used as a master, we will backport to MariaDB at least to the extent that new MariaDB versions will be able to replicate as slaves from a MySQL master without needing any special configuration. Though it depends on time available and priority against other work, for example there are known incompatibilities that have not yet been fixed in 10.0 alpha but will hopefully be fixed by 10.0 GA. Officially, replicating from new master to old slave is not supported (you should upgrade slaves first). This applies mostly the same whether MySQL or MariaDB or both are involved. Unofficially, as explained above, we do try to make it work as well as reasonably possible on the MariaDB side. > Before you say they are fully compatible, I point out at least > following types at mysql_com.h that do not exist on MariaDB mysql_com.h: > > MYSQL_TYPE_TIMESTAMP2, > MYSQL_TYPE_DATETIME2, > MYSQL_TYPE_TIME2, I do not know the details of this particular point (also you did not mention any version info). Best is probably to test it and see, and then report your findings and if needed we can file a bug for fixing things. - Kristian.

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Re: [Maria-developers] Getting community to write missing test cases
by Kristian Nielsen 21 May '13

21 May '13

Elena Stepanova <elenst(a)montyprogram.com> writes: > If we start doing it, Oracle will soon realize that this activity is > based at least as much on commit comments as on the code. As a result, > they will probably start making much vaguer comments than they do now, > which in turn might make merge and related activities even more > complicated than they are now. I wouldn't worry about that. First, I do not believe day-to-day developers spend any effort to actively conceal things for outside developers. The ban on bug test cases seems to have come from a generic security team mandate, which has roots some years back where Oracle were hit quite hard with countless vulnerabilities after their "can't break it - can't break in" campain. Second, even if they did, anything that makes Oracle close down more benefits the adoption of the forks. But most importantly, we must not get into the mentality that we let what Oracle might or might not do influence how we work. We need to go in whatever direction we believe is best for the project. Oracle has made it plain that they do not want to participate in the community, and we should just ignore them until such time as they might decide otherwise. - Kristian.

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[Maria-developers] Feature Request - Working auto_increment on BlackHole Engine
by Gordan Bobic 20 May '13

20 May '13

How difficult would be be to implement working auto-increment functionality on the BlackHole engine? This would be really useful for what I'm trying to do at the moment. Since it is not available and there are no sequences in MariaDB and MySQL, I have to resort to a hack such as a single-int-field table doing the auto-increment, and an insert trigger on the blackhole table to insert a null into the auto-increment tracking table, get LAST_INSERT_ID() to set the value in the auto-increment table, and then delete the record. Even with InnoDB log files and tablespace on tmpfs this makes the performance nosedive by a factor of 4 if the trigger doesn't bother cleaning up the auto-increment table, and a factor of 13 if it deletes the record immediately after inserting it. The actual times I tested with 24 inserter threads on a 24-thread server are 8m vs. 30m vs. 105m, i.e. a massive drop. Is there an better place than this list for a feature request? Gordan

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[Maria-developers] Ogg vorbis based table
by Roberto Spadim 18 May '13

18 May '13

Hi guys, i was listening some musics, and i had a idea... let's me explain Some systems are based in time and value, an example of scada systems. In this kind of system we have an 'channel' (like right or left sound channel) a timestamp and a value, normally a table like CREATE TABLE history( Channel int not null default 0, Datetimestamp decimal(22,7) not null default 0, Value decimal(22,5) default NULL, Primary key (channel,datetimestamp) ) Some explanations and features that scada systems use... Value can be NULL, in this case we could think like MUTE function on audio files Datetime normally are gmt, or unixtimestamp values with microsecond precision, they could be fixed interval or not, example... 1 2 3 4 5... (q second interval), in audio it's fixed sample rate, or not fixed interval (variable sample rate), like 1 3 4 9... Well what i'm thinking... today mariadb 10.0.2 started the CONNECT table type (please correct me if i'm wrong), that can 'connect' to a xml,txt,csv and others kinds of files to read and write it's values... Could we implement mp3, wave, ogg vorbis, file type type? This is a really nice 'table compression' for scada systems, and allow a new era of table type, think about... Select datetimestamp from someaudiofile where someniceaudiofunction()>1 In this example we could check date time where some scada value get over a fixed level, or where a frequency get higher and start a alarm condition, it could be used to get more information using statistics functions... i'm talking now about a new table type and new functions... but thats the idea... Anyone intested in this? About table compression think about compressing tax values in nasdaq for example, and execute a statistic analyse with this information... Well just some uses... Thanks for the space to show my idea and your time to read it Maybe a video table in future, or image based... just to use jpeg compreesion (x,y,color values) and others kinds of files... Bye

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[Maria-developers] Empty_queries vs Com_empty_queries
by Ian Gilfillan 18 May '13

18 May '13

I'm documenting the status variables at the moment, and have a question about Empty_queries vs Com_empty_queries. Com_empty_queries is not incremented when an empty result is returned, and appears to be incremented only when an empty query is sent to the server, eg: mysql --comments -e '-- sql comment' Empty_queries appears to match the empty queries returned with SHOW USER_STATISTICS. It increments each time a query is performed that returns an empty result. Currently the documentation on the user statistics page at https://kb.askmonty.org/en/user-statistics/ says that EMPTY_QUERIES (and therefore the Empty_queries status variable) is "The number of times this user's connections sent empty queries to the server", which would describe Com_empty_queries rather than Empty_queries, and would need to be corrected. The documentation on https://kb.askmonty.org/en/server-status-variables/ is what I've just written based on the above. Have I understood this correctly, or is there something else to it? thanks, ian

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[Maria-developers] To Sergei:
by Samarth Mathur 16 May '13

16 May '13

Hi Sergei.. just a few questions. Hope not to bother too much! does the .so file of two_questions exist in the mariadb 10.0.2 source code or was that just an example? Also, if I'm looking to implement pluggable authentication for LDAP, does the version of mariadb, i'm doing this on matter? if it does, which version would you recommend? I'm currently on v10.0.2.. What is the advantage of going for a pluggable authentication over say a module made for the PAM plugin in mariadb? Regards Sam

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Re: [Maria-developers] Feature Request - Working auto_inc rement on BlackHole Engine
by Gordan Bobic 16 May '13

16 May '13

On 05/15/2013 11:27 PM, Jocelyn Fournier wrote: > Hi Gordan, > > > Le 15/05/13 22:18, Gordan Bobic a écrit : >> On 05/15/2013 09:06 PM, Michael Widenius wrote: >>> >>> Hi! >>> >>>>>>>> "Gordan" == Gordan Bobic <gordan(a)bobich.net> writes: >>> >>> Gordan> How difficult would be be to implement working >>> Gordan> auto-increment functionality on the BlackHole engine? >>> >>> Gordan> This would be really useful for what I'm trying to do at >>> Gordan> the moment. Since it is not available and there are no >>> Gordan> sequences in MariaDB and MySQL, I have to resort to a >>> Gordan> hack such as a single-int-field table doing the >>> Gordan> auto-increment, and an insert trigger on the blackhole >>> Gordan> table to insert a null into the auto-increment >>> Gordan> tracking table, get LAST_INSERT_ID() to set the >>> Gordan> value in the auto-increment table, and then delete >>> Gordan> the record. >>> >>> What problem is that you wanted to solve? >>> Normally blackhole is used just for creating a slave of a slave that >>> doesn't have to hold any data (only the logs). >> >> The problem is a huge volume logging application that needs to have >> uniquely enumerated records for auditing purposes. > > Have you tried TokuDB engine ? It isn't suitable for what I am doing in this case - note that the blackhole engine in this case suits all of my requirements except for the working auto_increment functionality. I don't need to store the data on these nodes, merely binlog it up for further processing downstream. Gordan

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[Maria-developers] MariaDB GTID first impression
by Giuseppe Maxia 15 May '13

15 May '13

Kristian, Thanks for the docs. It's a very good start. Compared to MySQL 5.6, GTID in MariaDB has some advantages: it is enabled by default and it is easy to read. There are a few items, though, that should need some more thought: 1) rpl_slave_state is probably ill-named. In this architecture, it is only written by the slaves, and thus the name matches, but I wonder if the master should write this table (or a similar one) to keep track of its progress in the binary log. Rationale: all the info related to replication should be in tables and easy to query. 2) rpl_slave_state does not have enough metadata. What is missing here, and would be extremely useful, is the corresponding binlog+position for each GTID, a timestamp of when the transaction was saved to the binary log, and the timestamp of when it was applied. (The host name of the origin would also be useful). Also very important (when you will implement parallel replication) is a shard identifier. 3) Multiple domains do not integrate well with GTID. In multi-source replication, we use "connection names", but for GTID we use "domain numbers". They do not play well together : there is no correspondence between the gtid_domain_id and the connection name, and a "SHOW ALL SLAVES STATUS" lists all the GTID for every connection. For example: mysql -e 'show all slaves status\G' |grep 'Connection_name\|Running\|Master_Host\|Master_Port\|Gtid_Pos\|Master_Log' Connection_name: Bear Master_Host: 127.0.0.1 Master_Port: 8203 Master_Log_File: mysql-bin.000001 Read_Master_Log_Pos: 1020 Relay_Master_Log_File: mysql-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: Yes Exec_Master_Log_Pos: 1020 Gtid_Pos: 100-101-21,400-104-23,200-102-8,300-103-12,500-105-20 Connection_name: Wolf Master_Host: 127.0.0.1 Master_Port: 8204 Master_Log_File: mysql-bin.000001 Read_Master_Log_Pos: 896 Relay_Master_Log_File: mysql-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: Yes Exec_Master_Log_Pos: 896 Gtid_Pos: 100-101-21,400-104-23,200-102-8,300-103-12,500-105-20 Connection_name: Fox Master_Host: 127.0.0.1 Master_Port: 8205 Master_Log_File: mysql-bin.000002 Read_Master_Log_Pos: 365 Relay_Master_Log_File: mysql-bin.000002 Slave_IO_Running: Yes Slave_SQL_Running: Yes Exec_Master_Log_Pos: 365 Gtid_Pos: 100-101-21,400-104-23,200-102-8,300-103-12,500-105-20 Connection_name: Deer Master_Host: 127.0.0.1 Master_Port: 8206 Master_Log_File: mysql-bin.000001 Read_Master_Log_Pos: 1144 Relay_Master_Log_File: mysql-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: Yes Exec_Master_Log_Pos: 1144 Gtid_Pos: 100-101-21,400-104-23,200-102-8,300-103-12,500-105-20 Which connection is running which gtid number? Not easy to tell, as the correspondence between domain and connections is only in the DBA's head. 4) gtid_pos is text that includes all sequences from all domains. The docs say that I can modify it if needed, but in a case like the one above, modifying this string can be very error prone. For example, if server_ids are assigned using inet_aton(@IP), you could have a gtid_pos like this '1001-170062692-230000,1002-170062593-12893445,1003-170062700-672009,1003-170062699-700002' Instead of editing a string, and risk breaking replication in all domains, I would expect the availability of commands like: CHANGE GTID for domain 'Wolf' set gtid_pos=1900 That's it for now. Hope there is still room for improvements. Cheers Giuseppe

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