Hibernate column order

Most of the time it does not matter. However, the order of columns in a DB might impact the physical storage of the data.

Off the top of my head, ' order by s. There are those who, when presented with a glass that is exactly half full, say: this glass is half full. And then there are those who say: this glass is half empty. The world belongs, however, to those who can look at the glass and say: 'What's up with this glass? Excuse me? This is my glass? I don't think so.

Hibernate column order

Is it possible to use a JPA OrderColumn with Hibernate without making the order column nullable or giving it a default? I have an existing database with a sequence column mapped in a long-standing Hibernate 3. I tried to reproduce the mapping in the equivalent JPA with Kotlin:. The mapping as a whole seems to work, but Hibernate 5. Is there any way around this? That will allow Hibernate yo populate the FK more efficiently too. Check out this article for more details. Ok, it was already bidirectional, but perhaps not properly. If the auto-generated ecample uses the order column, you can debug that a d compare to your application to see where they differ. If you know why Hibernate is not generating the order column, I can fix that and then see if it uses the order column. It is a problem indeed.

Just wanted to say: An API where you can plug in your own strategy is good—it's not even really new configuration of Hibernate column order itself, it's really just a parameter of SchemaExport and no more.

Developers often use the schemas as generated by Hibernate but currently we order columns in table DDL by name which can lead to inefficient physical layouts on a few DBs due to the need for padding. I propose we create a SPI for the ordering as well as a configuration parameter and by default order by coalesce staticOrder, Integer. I'd also like to add some kind of possibility to specify the order of columns through a static ordinal per column, if possible, but that would probably require a few changes to some annotations. Beta Was this translation helpful? Give feedback. I created the topic on discourse , I would love to participate, but I suspect this may be outside my skill level.

Most of the time it does not matter. However, the order of columns in a DB might impact the physical storage of the data. Columns are ordered in the way they were added to the table. The smallint column will be padded to the same size as the bigint column due to a mechanism called alignment padding. This wastes both storage and performance since the additional bytes need to be read and written. Of course, the impact on smaller databases will be negligible. But in big databases, this might be a noticeable difference.

Hibernate column order

Summary: Required Optional Detail: Element. The persistence provider is responsible for maintaining the order upon retrieval and in the database. The persistence provider is responsible for updating the ordering upon flushing to the database to reflect any insertion, deletion, or reordering affecting the list. The OrderColumn annotation is specified on the side of the relationship that references the collection that is to be ordered. The order column is not visible as part of the state of the entity or embeddable class.

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I peeked around in the codebase and it looks doable without too much hassle, but I also understand that you need to keep the codebase clean without too many dirty hacks. ColumnIndex would be a truly inconvenient way to do that. And then there are those who say: this glass is half empty. ColumnOrderingStrategyStandard is the new default used strategy from v6. I agree with the solutions you mention and I think that this is how this should be used ideally. Off the top of my head, ' order by s. But it's terrible: I add a column to my table and in principle I might have to change an annotation on every other field. Column ordering SPI and annotations support for static ordering The default implementation would then order columns as outlined in the description above, which will make many users happy and can be used to solve the PK index selectivity issue Chris has in Envers due to the PK ordering. As to the second problem, it seems to me that it's much more natural to map the struct type to either:. That would be much more elegant than the ColumnOrder for the PK part of this issue in my opinion. Those 2 statements are mostly mutually exclusive ; which is currently not possible But it is - by managing the creation scripts yourself which has generally been the supported approach. Even more important than ordering regular columns would be ordering the columns in the primary key which is currently not possible. Share this. Copy link.

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Doing something potentially-helpful by default is also a fine idea: Exactly, I think it's really important we do not lose sight of the user experience in upgrading. Column ordering SPI and annotations support for static ordering beikov started this conversation in Design Proposals. Table; import org. And also because it looks more like an ordered list. Right, an API is great. Note that the interface HibernatePropertiesCustomizer is a SpringBoot-specific interface that provides the customize method to register the current class as the one to use for ordering the columns. Hibernate v6. Give feedback. Skip to content. Keep in mind that after a table is created columns cannot be reordered. I missed that. Ordering columns by their physical size on the disk might improve the performance and disk space used in your database if you have lots of data. But it's terrible: I add a column to my table and in principle I might have to change an annotation on every other field.