RE: Forced getter/setter access
Patrick, I meant tuned as in not including columns in the SQL update set clause if they weren't really changed by the app (even if a setter was called, the old and new values may be the same). The update set clause is 100% portable SQL. So I'm not entirely clear what you mean by: tuned for your implementation -Original Message- From: Patrick Linskey [mailto:[EMAIL PROTECTED] Sent: Wednesday, 4 April 2007 5:44 p.m. To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. ... tuned for your implementation, that is. Often, business needs require that a transaction involves a large number of objects, and it would be unfortunate to have to compromise on transaction integrity just for the sake of a particular implementation. It's not just a matter of needing to periodically call flush() during a tx, but rather of having to design transactions that don't read too many objects. Happily, with OpenJPA, this is a non-issue, regardless of property or field access. -Patrick -- Patrick Linskey BEA Systems, Inc. __ _ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Evan Ireland [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 10:39 PM To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access Granted, but with a reasonable implementation the cost should be low for: at commit / flush time compare the current values with the original values to figure out what to write back to the database. If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. Anyway at the end of the day, you must use the getters/setters because the spec says so, and you should write portable apps where possible :-) -Original Message- From: Patrick Linskey [mailto:[EMAIL PROTECTED] Sent: Wednesday, 4 April 2007 5:21 p.m. To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access The main reason to support getter / setter access is for implementations that cannot intercept field accesses. So, the getters and setters are there so that the JPA implementation can create a subclass of your entity type (hence the no-final-classes rule) and track what happens as you invoke the setters and getters. In other words, your business methods become part of the JPA implementation's domain. So, when using property access, your contract with the JPA provider is that you'll access persistent attributes only through the setters and getters, which allows the implementation to track what you do and when you do it. If you could directly access the underlying state, the implementation would have no way to know what happened during the course of a transaction. This, in turn, would mean that the implementation would have to keep a copy of every bit of data that you read during a transaction, and then at commit / flush time compare the current values with the original values to figure out what to write back to the database. As it turns out, when you use OpenJPA, all your direct field accesses are replaced with synthetic static methods anyways, so from a performance standpoint, you'll see equivalent behavior either way. In my experience, persistent domain model field access performance in tight loops is rarely actually a performance bottleneck; it's almost always going back and forth to the database that ends up being the bottleneck, and thus the most important place to optimize. -Patrick -- Patrick Linskey BEA Systems, Inc. __ _ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error
RE: Forced getter/setter access
Ah... I was referring to the fact that if an implementation isn't tracking field accesses, then it must sit around and do in-mem comparisons (and hold onto hard refs to copies of all read data) in order to figure out what to write back to the DB. So, I was referring solely to the in-mem computation time, not to SQL generation. -Patrick -- Patrick Linskey BEA Systems, Inc. ___ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Evan Ireland [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 11:04 PM To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access Patrick, I meant tuned as in not including columns in the SQL update set clause if they weren't really changed by the app (even if a setter was called, the old and new values may be the same). The update set clause is 100% portable SQL. So I'm not entirely clear what you mean by: tuned for your implementation -Original Message- From: Patrick Linskey [mailto:[EMAIL PROTECTED] Sent: Wednesday, 4 April 2007 5:44 p.m. To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. ... tuned for your implementation, that is. Often, business needs require that a transaction involves a large number of objects, and it would be unfortunate to have to compromise on transaction integrity just for the sake of a particular implementation. It's not just a matter of needing to periodically call flush() during a tx, but rather of having to design transactions that don't read too many objects. Happily, with OpenJPA, this is a non-issue, regardless of property or field access. -Patrick -- Patrick Linskey BEA Systems, Inc. __ _ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Evan Ireland [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 10:39 PM To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access Granted, but with a reasonable implementation the cost should be low for: at commit / flush time compare the current values with the original values to figure out what to write back to the database. If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. Anyway at the end of the day, you must use the getters/setters because the spec says so, and you should write portable apps where possible :-) -Original Message- From: Patrick Linskey [mailto:[EMAIL PROTECTED] Sent: Wednesday, 4 April 2007 5:21 p.m. To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access The main reason to support getter / setter access is for implementations that cannot intercept field accesses. So, the getters and setters are there so that the JPA implementation can create a subclass of your entity type (hence the no-final-classes rule) and track what happens as you invoke the setters and getters. In other words, your business methods become part of the JPA implementation's domain. So, when using property access, your contract with the JPA provider is that you'll access persistent attributes only through the setters and getters, which allows the implementation to track what you do and when you do it. If you could directly access the underlying state, the implementation would have no way to know what happened during the course of a transaction. This, in turn, would mean that the implementation would have to keep a copy of every bit of data that you read during a transaction
RE: Forced getter/setter access
The main reason to support getter / setter access is for implementations that cannot intercept field accesses. So, the getters and setters are there so that the JPA implementation can create a subclass of your entity type (hence the no-final-classes rule) and track what happens as you invoke the setters and getters. In other words, your business methods become part of the JPA implementation's domain. So, when using property access, your contract with the JPA provider is that you'll access persistent attributes only through the setters and getters, which allows the implementation to track what you do and when you do it. If you could directly access the underlying state, the implementation would have no way to know what happened during the course of a transaction. This, in turn, would mean that the implementation would have to keep a copy of every bit of data that you read during a transaction, and then at commit / flush time compare the current values with the original values to figure out what to write back to the database. As it turns out, when you use OpenJPA, all your direct field accesses are replaced with synthetic static methods anyways, so from a performance standpoint, you'll see equivalent behavior either way. In my experience, persistent domain model field access performance in tight loops is rarely actually a performance bottleneck; it's almost always going back and forth to the database that ends up being the bottleneck, and thus the most important place to optimize. -Patrick -- Patrick Linskey BEA Systems, Inc. ___ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Phill Moran [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 10:02 PM To: open-jpa-dev@incubator.apache.org Subject: Forced getter/setter access Can anyone explain why this rule is in effect: When using property access, only the getter and setter method for a property should ever access the underlying persistent field directly. Other methods, including internal business methods in the persistent class, should go through the getter and setter methods when manipulating persistent state. (section 2.1.4 OpenJPA manual) This seems rather execution costly. If ,for instance, I have a Size class with hieght, width and length then to calculate and return volume I suffer a three method call overhead: return getWidth() * getLength() * getHieght(); This is opposed to a more efficient Return height * width * length Phill Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
RE: Forced getter/setter access
Granted, but with a reasonable implementation the cost should be low for: at commit / flush time compare the current values with the original values to figure out what to write back to the database. If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. Anyway at the end of the day, you must use the getters/setters because the spec says so, and you should write portable apps where possible :-) -Original Message- From: Patrick Linskey [mailto:[EMAIL PROTECTED] Sent: Wednesday, 4 April 2007 5:21 p.m. To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access The main reason to support getter / setter access is for implementations that cannot intercept field accesses. So, the getters and setters are there so that the JPA implementation can create a subclass of your entity type (hence the no-final-classes rule) and track what happens as you invoke the setters and getters. In other words, your business methods become part of the JPA implementation's domain. So, when using property access, your contract with the JPA provider is that you'll access persistent attributes only through the setters and getters, which allows the implementation to track what you do and when you do it. If you could directly access the underlying state, the implementation would have no way to know what happened during the course of a transaction. This, in turn, would mean that the implementation would have to keep a copy of every bit of data that you read during a transaction, and then at commit / flush time compare the current values with the original values to figure out what to write back to the database. As it turns out, when you use OpenJPA, all your direct field accesses are replaced with synthetic static methods anyways, so from a performance standpoint, you'll see equivalent behavior either way. In my experience, persistent domain model field access performance in tight loops is rarely actually a performance bottleneck; it's almost always going back and forth to the database that ends up being the bottleneck, and thus the most important place to optimize. -Patrick -- Patrick Linskey BEA Systems, Inc. __ _ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Phill Moran [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 10:02 PM To: open-jpa-dev@incubator.apache.org Subject: Forced getter/setter access Can anyone explain why this rule is in effect: When using property access, only the getter and setter method for a property should ever access the underlying persistent field directly. Other methods, including internal business methods in the persistent class, should go through the getter and setter methods when manipulating persistent state. (section 2.1.4 OpenJPA manual) This seems rather execution costly. If ,for instance, I have a Size class with hieght, width and length then to calculate and return volume I suffer a three method call overhead: return getWidth() * getLength() * getHieght(); This is opposed to a more efficient Return height * width * length Phill Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
RE: Forced getter/setter access
If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. ... tuned for your implementation, that is. Often, business needs require that a transaction involves a large number of objects, and it would be unfortunate to have to compromise on transaction integrity just for the sake of a particular implementation. It's not just a matter of needing to periodically call flush() during a tx, but rather of having to design transactions that don't read too many objects. Happily, with OpenJPA, this is a non-issue, regardless of property or field access. -Patrick -- Patrick Linskey BEA Systems, Inc. ___ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Evan Ireland [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 10:39 PM To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access Granted, but with a reasonable implementation the cost should be low for: at commit / flush time compare the current values with the original values to figure out what to write back to the database. If you are going to issue tuned updates to the DB, determining what really changed (as opposed to what setter methods were called) can avoid unnecessary DB overheads. Anyway at the end of the day, you must use the getters/setters because the spec says so, and you should write portable apps where possible :-) -Original Message- From: Patrick Linskey [mailto:[EMAIL PROTECTED] Sent: Wednesday, 4 April 2007 5:21 p.m. To: open-jpa-dev@incubator.apache.org Subject: RE: Forced getter/setter access The main reason to support getter / setter access is for implementations that cannot intercept field accesses. So, the getters and setters are there so that the JPA implementation can create a subclass of your entity type (hence the no-final-classes rule) and track what happens as you invoke the setters and getters. In other words, your business methods become part of the JPA implementation's domain. So, when using property access, your contract with the JPA provider is that you'll access persistent attributes only through the setters and getters, which allows the implementation to track what you do and when you do it. If you could directly access the underlying state, the implementation would have no way to know what happened during the course of a transaction. This, in turn, would mean that the implementation would have to keep a copy of every bit of data that you read during a transaction, and then at commit / flush time compare the current values with the original values to figure out what to write back to the database. As it turns out, when you use OpenJPA, all your direct field accesses are replaced with synthetic static methods anyways, so from a performance standpoint, you'll see equivalent behavior either way. In my experience, persistent domain model field access performance in tight loops is rarely actually a performance bottleneck; it's almost always going back and forth to the database that ends up being the bottleneck, and thus the most important place to optimize. -Patrick -- Patrick Linskey BEA Systems, Inc. __ _ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. -Original Message- From: Phill Moran [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 10:02 PM To: open-jpa-dev@incubator.apache.org Subject: Forced getter/setter access Can anyone explain why this rule is in effect: When using property access, only the getter and setter method for a property should ever access the underlying persistent field directly. Other methods, including internal business methods in the persistent class, should go through the getter and setter methods when manipulating persistent state. (section
