Hibernate column order

Is it possible to use a JPA OrderColumn with Hibernate without making the order column nullable or giving it a default?

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

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. My initial idea was a somewhat simple hack where you could set a property that toggles the following feature:. If possible would just retain the order in which the fields were defined in the java class. If this is not possible I suspect the JVM spec does not guarantee any ordering when traversing fields then add a simple ordering annotation that can be used with a comparator to sort the non-id columns prior to generation. 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. The ColumnOrder annotation is actually an addition that allows fine grained control of the order. The main addition would be the SPI that allows automatic ordering based on some logic which a user configures just once.

The OrderBy annotation is not used when OrderColumn is specified.

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.

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. If you now put the bigint column first you save 6 bytes per row. Keep in mind that after a table is created columns cannot be reordered.

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.

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Summary: Required Optional Detail: Element. I would strongly caution that whatever we do annotation-wise that there is a comparable solution for XML mappings. I think we could reuse the Index annotation for this. If users wish to invent a crappy ColumnOrder annotation than they can do that. But yeah, despite my grumble, I ultimately do think this makes sense. Suggestions welcome. Check out this article for more details. Thanks a bunch On 4 Nov. Unordered list. Discussion options. Testing Testing was done using Spring Boot v3. The persistence provider is responsible for updating the ordering upon flushing to the database to reflect any insertion, deletion, or reordering affecting the list. Comment options. My personal aesthetic preference would be something like:.

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Ordering columns might also improve the readability of the data in the tool you use to browse the DB. Table; import org. 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. Other than that, I think there is no need for explicit column ordering. ColumnOrderingStrategy was introduced for this purpose which can be used to order columns. It is a problem indeed. Maybe we should split off the discussion about the static ordering as that is really only interesting for supporting struct types. To extract all employees that can perform a certain service I use: return Service. As to the second problem, it seems to me that it's much more natural to map the struct type to either:. I know in HBM that an application can specify an index name on the property mappings in the primary key; however, I don't believe there is anything that can be passed to indicate uniqueness currently. I'm have no real knowledge of the hibernate internals, but I work on a project where we drive our data model through JPA combined with flyway. Column ordering SPI and annotations support for static ordering Best regards Jens Beta Was this translation helpful?