chainable key path Qualifier question.
I am trying to get handy with ERXKey. However, how does one go across relationships? Say I want to find all order items for a store: It doesn't know to traverse ORDER_ERXKEY to the STORE_ERXKEY OrderItems.ORDER_ERXKEY.STORE_ERXKEY.eq(store); How does one properly construct this query? Thanks ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: chainable key path Qualifier question.
have you seen the method called dot() ? stuff like: (Article.AUTHOR.dot(User.POSTER_ID)) dot rocks the box. On May 17, 2013, at 11:50 AM, James Cicenia ja...@jimijon.com wrote: I am trying to get handy with ERXKey. However, how does one go across relationships? Say I want to find all order items for a store: It doesn't know to traverse ORDER_ERXKEY to the STORE_ERXKEY OrderItems.ORDER_ERXKEY.STORE_ERXKEY.eq(store); How does one properly construct this query? Thanks ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/jtayler%40oeinc.com This email sent to jtay...@oeinc.com ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: chainable key path Qualifier question.
Ah! Missed that key little method. Thanks On May 17, 2013, at 11:04 AM, Jesse Tayler jtay...@oeinc.com wrote: have you seen the method called dot() ? stuff like: (Article.AUTHOR.dot(User.POSTER_ID)) dot rocks the box. On May 17, 2013, at 11:50 AM, James Cicenia ja...@jimijon.com wrote: I am trying to get handy with ERXKey. However, how does one go across relationships? Say I want to find all order items for a store: It doesn't know to traverse ORDER_ERXKEY to the STORE_ERXKEY OrderItems.ORDER_ERXKEY.STORE_ERXKEY.eq(store); How does one properly construct this query? Thanks ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/jtayler%40oeinc.com This email sent to jtay...@oeinc.com ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Duplicate entry '4183884' for key 'PRIMARY'
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 NSDictionaryString, Object
primaryKeyForNewRowWithEntity(EOEntity entity){
return null;
}
Any advise would be appreciated,
Thanks,
Mark
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Re: Duplicate entry '4183884' for key 'PRIMARY'
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 go...@mac.com 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 NSDictionaryString, Object primaryKeyForNewRowWithEntity(EOEntity
entity){
return null;
}
Any advise would be appreciated,
Thanks,
Mark
___
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Re: Duplicate entry '4183884' for key 'PRIMARY'
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 go...@mac.com 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 go...@mac.com 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 NSDictionaryString, Object
primaryKeyForNewRowWithEntity(EOEntity entity){
return null;
}
Any advise would be appreciated,
Thanks,
Mark
___
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