Re: Changing database tables to different storage engine.
Hi All Sorry but things have now changed, and I found the following. The tables was in fact restored as Innodb, however someone seems to have gone and changed something causing innodb to be disabled, this caused the tables to be defaulted back to MyIsam. Should this not rather have just resulted in an error allowing to fix the problem in the first place instead of changing the storage engines? Anyone have some thoughts on the best solution to fix this? I will look into the innodb not working soon. Machiel -Original Message- From: Machiel Richards machi...@rdc.co.za To: mysql mailing list mysql@lists.mysql.com Subject: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 11:59:03 +0200 Good day all Hope all is well. I have something to ask as someone might have done this as well and may have a good solution on how to fix this. During a database migration this weekend to move a MySQL database from windows to linux, we created a backup and restore of the database. However, form my part I made a mistake by overlooking the fact that the windows database was configured to use default storage engine as Innodb. On the new server, the default was set to MyIsam. This resulted in all the tables being restored to the new system as MyIsam instead of Innodb. In order to fix this, I know you can use alter table to change the storage engine, however I need to know the following: 1. this is a production system and can't afford any downtime or as little performance degration as possible. What is the best way to do this in order to have the least amount of effect on the database and it's performance? Regards Machiel
Re: Changing database tables to different storage engine.
I have frequently seen Innodb 'silently' disabled if the innodb_log_file_size is different to the files size on disk (quite common when moving systems about). You wont be able to use innodb until you resolve this either by deleting the log files and restarting mysqld so they get recreated or changing the innodb_log_file_size to match the size of the files on disk. If the Innodb engine is not available then MySQL will use the default (usually MyISAM) storage engine even if Innodb was specified. You can stop this behaviour by setting sql-mode=NO_ENGINE_SUBSTITUTION Regards John On 22 November 2010 10:12, Machiel Richards machiel.richa...@gmail.comwrote: Hi All Sorry but things have now changed, and I found the following. The tables was in fact restored as Innodb, however someone seems to have gone and changed something causing innodb to be disabled, this caused the tables to be defaulted back to MyIsam. Should this not rather have just resulted in an error allowing to fix the problem in the first place instead of changing the storage engines? Anyone have some thoughts on the best solution to fix this? I will look into the innodb not working soon. Machiel -Original Message- From: Machiel Richards machi...@rdc.co.za To: mysql mailing list mysql@lists.mysql.com Subject: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 11:59:03 +0200 Good day all Hope all is well. I have something to ask as someone might have done this as well and may have a good solution on how to fix this. During a database migration this weekend to move a MySQL database from windows to linux, we created a backup and restore of the database. However, form my part I made a mistake by overlooking the fact that the windows database was configured to use default storage engine as Innodb. On the new server, the default was set to MyIsam. This resulted in all the tables being restored to the new system as MyIsam instead of Innodb. In order to fix this, I know you can use alter table to change the storage engine, however I need to know the following: 1. this is a production system and can't afford any downtime or as little performance degration as possible. What is the best way to do this in order to have the least amount of effect on the database and it's performance? Regards Machiel -- John Daisley Certified MySQL 5 Database Administrator Certified MySQL 5 Developer Cognos BI Developer Telephone: +44 (0)7918 621621 Email: john.dais...@butterflysystems.co.uk
Re: Changing database tables to different storage engine.
Thank you John I have in the meantime fond this to be the case (** someone changed config files without my knowledge it seems as this was setup properly and working**) Anyhow, in order for the innodb to be active again I need to restart the database, however aftewards I assume the tables will still be MyIsam. In this event I will need to manually alter each table, and I am concerned about the impact of this on the system performance. Regards Machiel -Original Message- From: John Daisley daisleyj...@googlemail.com To: Machiel Richards machiel.richa...@gmail.com Cc: mysql mailing list mysql@lists.mysql.com Subject: Re: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 10:51:23 + I have frequently seen Innodb 'silently' disabled if the innodb_log_file_size is different to the files size on disk (quite common when moving systems about). You wont be able to use innodb until you resolve this either by deleting the log files and restarting mysqld so they get recreated or changing the innodb_log_file_size to match the size of the files on disk. If the Innodb engine is not available then MySQL will use the default (usually MyISAM) storage engine even if Innodb was specified. You can stop this behaviour by setting sql-mode=NO_ENGINE_SUBSTITUTION Regards John On 22 November 2010 10:12, Machiel Richards machiel.richa...@gmail.com wrote: Hi All Sorry but things have now changed, and I found the following. The tables was in fact restored as Innodb, however someone seems to have gone and changed something causing innodb to be disabled, this caused the tables to be defaulted back to MyIsam. Should this not rather have just resulted in an error allowing to fix the problem in the first place instead of changing the storage engines? Anyone have some thoughts on the best solution to fix this? I will look into the innodb not working soon. Machiel -Original Message- From: Machiel Richards machi...@rdc.co.za To: mysql mailing list mysql@lists.mysql.com Subject: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 11:59:03 +0200 Good day all Hope all is well. I have something to ask as someone might have done this as well and may have a good solution on how to fix this. During a database migration this weekend to move a MySQL database from windows to linux, we created a backup and restore of the database. However, form my part I made a mistake by overlooking the fact that the windows database was configured to use default storage engine as Innodb. On the new server, the default was set to MyIsam. This resulted in all the tables being restored to the new system as MyIsam instead of Innodb. In order to fix this, I know you can use alter table to change the storage engine, however I need to know the following: 1. this is a production system and can't afford any downtime or as little performance degration as possible. What is the best way to do this in order to have the least amount of effect on the database and it's performance? Regards Machiel -- John Daisley Certified MySQL 5 Database Administrator Certified MySQL 5 Developer Cognos BI Developer Telephone: +44 (0)7918 621621 Email: john.dais...@butterflysystems.co.uk
Re: Changing database tables to different storage engine.
On Mon, Nov 22, 2010 at 11:55 AM, Machiel Richards machiel.richa...@gmail.com wrote: In this event I will need to manually alter each table, and I am concerned about the impact of this on the system performance. That will indeed make for quite some locking time, depending on the size of your tables. It's going to be hard to get around that, unfortunately. What you could do, is create temporary tables, populate them with using insert into...select and then alter table rename them into place. One hell of a job if you have many tables, though, and even then you may feel some impact on performance. -- Bier met grenadyn Is als mosterd by den wyn Sy die't drinkt, is eene kwezel Hy die't drinkt, is ras een ezel
Re: Changing database tables to different storage engine.
Machiel, Each table will be write locked while it is being altered so this will most likely impact the application. In addition to the write lock, the conversion causes each table to be completely rewritten in the new format so this will have a high impact on IO write activity and so it will impact overall IO throughput. If your application is mostly reads, is well cached in memory, and the tables are small this should be pretty fast and relatively pain free. If you aren't sure about the impact and conversion time you may want to restore a backup of the database to another location and run through the conversion while monitoring performance numbers. Tyler On 11/22/10 5:55 AM, Machiel Richards wrote: Thank you John I have in the meantime fond this to be the case (** someone changed config files without my knowledge it seems as this was setup properly and working**) Anyhow, in order for the innodb to be active again I need to restart the database, however aftewards I assume the tables will still be MyIsam. In this event I will need to manually alter each table, and I am concerned about the impact of this on the system performance. Regards Machiel -Original Message- From: John Daisleydaisleyj...@googlemail.com To: Machiel Richardsmachiel.richa...@gmail.com Cc: mysql mailing listmysql@lists.mysql.com Subject: Re: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 10:51:23 + I have frequently seen Innodb 'silently' disabled if the innodb_log_file_size is different to the files size on disk (quite common when moving systems about). You wont be able to use innodb until you resolve this either by deleting the log files and restarting mysqld so they get recreated or changing the innodb_log_file_size to match the size of the files on disk. If the Innodb engine is not available then MySQL will use the default (usually MyISAM) storage engine even if Innodb was specified. You can stop this behaviour by setting sql-mode=NO_ENGINE_SUBSTITUTION Regards John On 22 November 2010 10:12, Machiel Richardsmachiel.richa...@gmail.com wrote: Hi All Sorry but things have now changed, and I found the following. The tables was in fact restored as Innodb, however someone seems to have gone and changed something causing innodb to be disabled, this caused the tables to be defaulted back to MyIsam. Should this not rather have just resulted in an error allowing to fix the problem in the first place instead of changing the storage engines? Anyone have some thoughts on the best solution to fix this? I will look into the innodb not working soon. Machiel -Original Message- From: Machiel Richardsmachi...@rdc.co.za To: mysql mailing listmysql@lists.mysql.com Subject: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 11:59:03 +0200 Good day all Hope all is well. I have something to ask as someone might have done this as well and may have a good solution on how to fix this. During a database migration this weekend to move a MySQL database from windows to linux, we created a backup and restore of the database. However, form my part I made a mistake by overlooking the fact that the windows database was configured to use default storage engine as Innodb. On the new server, the default was set to MyIsam. This resulted in all the tables being restored to the new system as MyIsam instead of Innodb. In order to fix this, I know you can use alter table to change the storage engine, however I need to know the following: 1. this is a production system and can't afford any downtime or as little performance degration as possible. What is the best way to do this in order to have the least amount of effect on the database and it's performance? Regards Machiel -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/mysql?unsub=arch...@jab.org
Re: Changing database tables to different storage engine.
Another option, if your data hasn't changed in the mean time (I know, rare scenario) could be to set up a secondary instance from the same binaries and changing only the datafile location and the port in the config, re-importing, shutting both instances down and switching out the datafiles. You'll get some performance impact from the import's disk activity, but the switch should take almost no time - if the datafiles are on the same physical disk, of course. On Mon, Nov 22, 2010 at 3:24 PM, Tyler Poland tpol...@engineyard.comwrote: Machiel, Each table will be write locked while it is being altered so this will most likely impact the application. In addition to the write lock, the conversion causes each table to be completely rewritten in the new format so this will have a high impact on IO write activity and so it will impact overall IO throughput. If your application is mostly reads, is well cached in memory, and the tables are small this should be pretty fast and relatively pain free. If you aren't sure about the impact and conversion time you may want to restore a backup of the database to another location and run through the conversion while monitoring performance numbers. Tyler On 11/22/10 5:55 AM, Machiel Richards wrote: Thank you John I have in the meantime fond this to be the case (** someone changed config files without my knowledge it seems as this was setup properly and working**) Anyhow, in order for the innodb to be active again I need to restart the database, however aftewards I assume the tables will still be MyIsam. In this event I will need to manually alter each table, and I am concerned about the impact of this on the system performance. Regards Machiel -Original Message- From: John Daisleydaisleyj...@googlemail.com To: Machiel Richardsmachiel.richa...@gmail.com Cc: mysql mailing listmysql@lists.mysql.com Subject: Re: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 10:51:23 + I have frequently seen Innodb 'silently' disabled if the innodb_log_file_size is different to the files size on disk (quite common when moving systems about). You wont be able to use innodb until you resolve this either by deleting the log files and restarting mysqld so they get recreated or changing the innodb_log_file_size to match the size of the files on disk. If the Innodb engine is not available then MySQL will use the default (usually MyISAM) storage engine even if Innodb was specified. You can stop this behaviour by setting sql-mode=NO_ENGINE_SUBSTITUTION Regards John On 22 November 2010 10:12, Machiel Richardsmachiel.richa...@gmail.com wrote: Hi All Sorry but things have now changed, and I found the following. The tables was in fact restored as Innodb, however someone seems to have gone and changed something causing innodb to be disabled, this caused the tables to be defaulted back to MyIsam. Should this not rather have just resulted in an error allowing to fix the problem in the first place instead of changing the storage engines? Anyone have some thoughts on the best solution to fix this? I will look into the innodb not working soon. Machiel -Original Message- From: Machiel Richardsmachi...@rdc.co.za To: mysql mailing listmysql@lists.mysql.com Subject: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 11:59:03 +0200 Good day all Hope all is well. I have something to ask as someone might have done this as well and may have a good solution on how to fix this. During a database migration this weekend to move a MySQL database from windows to linux, we created a backup and restore of the database. However, form my part I made a mistake by overlooking the fact that the windows database was configured to use default storage engine as Innodb. On the new server, the default was set to MyIsam. This resulted in all the tables being restored to the new system as MyIsam instead of Innodb. In order to fix this, I know you can use alter table to change the storage engine, however I need to know the following: 1. this is a production system and can't afford any downtime or as little performance degration as possible. What is the best way to do this in order to have the least amount of effect on the database and it's performance
Re: Changing database tables to different storage engine.
Another thing to keep in mind is to make sure all your foreign keys are re-created if you have any. We had a similar accident in our prod box a few years back and converting MyIsam to InnoDB won't necessarily re-create the foreign keys. Kyong On Mon, Nov 22, 2010 at 6:39 AM, Johan De Meersman vegiv...@tuxera.be wrote: Another option, if your data hasn't changed in the mean time (I know, rare scenario) could be to set up a secondary instance from the same binaries and changing only the datafile location and the port in the config, re-importing, shutting both instances down and switching out the datafiles. You'll get some performance impact from the import's disk activity, but the switch should take almost no time - if the datafiles are on the same physical disk, of course. On Mon, Nov 22, 2010 at 3:24 PM, Tyler Poland tpol...@engineyard.comwrote: Machiel, Each table will be write locked while it is being altered so this will most likely impact the application. In addition to the write lock, the conversion causes each table to be completely rewritten in the new format so this will have a high impact on IO write activity and so it will impact overall IO throughput. If your application is mostly reads, is well cached in memory, and the tables are small this should be pretty fast and relatively pain free. If you aren't sure about the impact and conversion time you may want to restore a backup of the database to another location and run through the conversion while monitoring performance numbers. Tyler On 11/22/10 5:55 AM, Machiel Richards wrote: Thank you John I have in the meantime fond this to be the case (** someone changed config files without my knowledge it seems as this was setup properly and working**) Anyhow, in order for the innodb to be active again I need to restart the database, however aftewards I assume the tables will still be MyIsam. In this event I will need to manually alter each table, and I am concerned about the impact of this on the system performance. Regards Machiel -Original Message- From: John Daisleydaisleyj...@googlemail.com To: Machiel Richardsmachiel.richa...@gmail.com Cc: mysql mailing listmysql@lists.mysql.com Subject: Re: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 10:51:23 + I have frequently seen Innodb 'silently' disabled if the innodb_log_file_size is different to the files size on disk (quite common when moving systems about). You wont be able to use innodb until you resolve this either by deleting the log files and restarting mysqld so they get recreated or changing the innodb_log_file_size to match the size of the files on disk. If the Innodb engine is not available then MySQL will use the default (usually MyISAM) storage engine even if Innodb was specified. You can stop this behaviour by setting sql-mode=NO_ENGINE_SUBSTITUTION Regards John On 22 November 2010 10:12, Machiel Richardsmachiel.richa...@gmail.com wrote: Hi All Sorry but things have now changed, and I found the following. The tables was in fact restored as Innodb, however someone seems to have gone and changed something causing innodb to be disabled, this caused the tables to be defaulted back to MyIsam. Should this not rather have just resulted in an error allowing to fix the problem in the first place instead of changing the storage engines? Anyone have some thoughts on the best solution to fix this? I will look into the innodb not working soon. Machiel -Original Message- From: Machiel Richardsmachi...@rdc.co.za To: mysql mailing listmysql@lists.mysql.com Subject: Changing database tables to different storage engine. Date: Mon, 22 Nov 2010 11:59:03 +0200 Good day all Hope all is well. I have something to ask as someone might have done this as well and may have a good solution on how to fix this. During a database migration this weekend to move a MySQL database from windows to linux, we created a backup and restore of the database. However, form my part I made a mistake by overlooking the fact that the windows database was configured to use default storage engine as Innodb. On the new server, the default was set to MyIsam. This resulted in all the tables being restored to the new system as MyIsam instead of Innodb. In order to fix this, I know you can use alter table to change the storage engine, however I need to know the following
