I recommend configuring the InnoDB settings before you start conversion. See the example configs on github project. The reason is that some settings are harder to change after you have starting using InnoDB with default and probably suboptimal settings.
And yeah, that command will do the conversion properly. Simple to convert. Study the example configs. They are documented. Regards, Kieran. (Sent from my iPhone) On May 18, 2013, at 7:10 AM, Mark Gowdy <[email protected]> wrote: > Using SequalPro, it lets me change the table type (in the Table Info tab). > This issues the statement: > ALTER TABLE `EO_PK_TABLE` ENGINE = InnoDB; > > Is there any likely downside to this, compared with recreating the schema > from scratch? > > Mark > > > > On 17 May 2013, at 23:26, Kieran Kelleher wrote: > >> InnoDB is all or nothing ..... don't waste your time mixing InnoDB and >> MyISAM in transactions - makes the results even more confusing. >> >> Convert them all..... evidently, InnoDB is faster nowadays anyway. innoDB >> can cache everything in memory. MyISAM IIRC only can cache PKs in memory and >> must always get rows from disk. There is no benefit to staying on MyISAM >> format. >> >> >> On May 17, 2013, at 4:36 PM, Mark Gowdy <[email protected]> wrote: >> >>> Thanks Paul, it looks like you are correct. >>> >>> Two 'Kieran Kelleher' email stated: >>> >>>> There is also no row locking on EO_PK_TABLE with myisam, so you will get >>>> primary key clashes and subsequent failed inserts if the db is >>>> sufficiently contended. >>> >>> >>> and >>> >>>> (1) Never use MyISAM - no transactional support means a failed >>>> editingContext.saveChanges() will not result in a rollback and semi-saved >>>> changes to the database..... data integrity goes out the window. Use >>>> InnoDB .... don't just convert live DB though, dump/import to a standby >>>> server, configure InnoDB first completely and actually do a little bit of >>>> studying the MySQL docs to understand how. Also, get a head start here: >>>> https://github.com/kierankelleher/gic-mysql-tools >>>> >>>> (2) Don't create "real" foreign key constraints because MySQL does not >>>> support deferred constraints (which is the biggest negative of using >>>> MySQL). Instead just manually create indexes on every foreign key field. >>>> Otherwise your performance will deteriorate as tables sizes get larger. >>> >>> Seems like sound advise. >>> I now have some careful un-picking to do. >>> >>> Also, incase anyone is interested, I eventually found the primary key >>> generation code in JDBCPlugIn.class : newPrimaryKeys(int count, EOEntity >>> entity, JDBCChannel channel) >>> Other DB plugins do their own thing, but the MySQL one appears to fall back >>> on JDBCPlugIn. >>> >>> Thanks again, >>> >>> Mark >>> >>> >>> On 17 May 2013, at 21:18, Paul Yu wrote: >>> >>>> Well you certainly should not use MyIsam system. Innodb is the right >>>> answer. See Kieran's post on this subject. >>>> >>>> But I'm not sure that will be the end of your issues. >>>> >>>> Sent from my iPad >>>> >>>> On May 17, 2013, at 4:03 PM, Mark Gowdy <[email protected]> wrote: >>>> >>>>> Hi, >>>>> >>>>> We have started getting more of these errors recently, now that the >>>>> system is under more load. >>>>> >>>>> ---- >>>>> EvaluateExpression failed: >>>>> <com.webobjects.jdbcadaptor._MySQLPlugIn$MySQLExpression: "INSERT INTO >>>>> queue_item(ITEM_DATE, ... etc....) >>>>> Duplicate entry '4183884' for key 'PRIMARY' >>>>> ---- >>>>> >>>>> I believe the problem is due to the fact that there is more than one >>>>> instance trying to write to the 'queue_item' table, and the EO_PK_TABLE >>>>> mechanism is handing out the same ID more than once. >>>>> Probably something to do with locking. >>>>> >>>>> Our Database is MySQL 5, and the EO_PK_TABLE is of type MyISAM. >>>>> >>>>> I tried to find the mechanism that allocate the primary key, but I keep >>>>> bumping up against: >>>>> >>>>> EOAdaptorChannel: >>>>> @Deprecated >>>>> public NSDictionary<String, Object> >>>>> primaryKeyForNewRowWithEntity(EOEntity entity){ >>>>> return null; >>>>> } >>>>> >>>>> >>>>> Any advise would be appreciated, >>>>> >>>>> Thanks, >>>>> >>>>> Mark >>>>> >>>>> _______________________________________________ >>>>> Do not post admin requests to the list. They will be ignored. >>>>> Webobjects-dev mailing list ([email protected]) >>>>> Help/Unsubscribe/Update your Subscription: >>>>> https://lists.apple.com/mailman/options/webobjects-dev/pyu%40mac.com >>>>> >>>>> This email sent to [email protected] >>> >>> _______________________________________________ >>> Do not post admin requests to the list. They will be ignored. >>> Webobjects-dev mailing list ([email protected]) >>> Help/Unsubscribe/Update your Subscription: >>> https://lists.apple.com/mailman/options/webobjects-dev/kelleherk%40gmail.com >>> >>> This email sent to [email protected] >
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