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 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. 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.

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 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. 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.

If you are configuring your hibernate properties in Java code you can use the AvailableSettings.

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?

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 v6.

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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One way to implement our own ColumnOrderingStrategy is to implement the interface ColumnOrderingStrategy and its 4 methods:. Testing Testing was done using Spring Boot v3. And I think this one is actually pretty important. To unsubscribe from this group, send email to play-framewor The order column will be valued when you insert your objects to ensure that when you retrieve them they will be in the same order. Is it possible to use a JPA OrderColumn with Hibernate without making the order column nullable or giving it a default? Unordered list. Summary: Required Optional Detail: Element. I think that our annotations usually work by mapping Java elements to database tables or columns. So I have not changed my opinion that annotating fields of entities with integers is inelegant, verbose, and extremely fragile if I add a field, I need to renumber existing fields. Updated my test case to move the OrderColumn back. 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.

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Unordered list. I actually think matching the column names is great as that would allow a user to provide a name for the PK constraint. Copy link. That would be much more elegant than the ColumnOrder for the PK part of this issue in my opinion. It is a problem indeed. This is my glass? So that's in principle pretty low-impact and very flexible. It sorts columns roughly by this algorithm:. Column; import org. ColumnOrderingStrategyLegacy is essentially a no-op implementation and should resemble the behavior before Hibernate v6. 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. I would strongly caution that whatever we do annotation-wise that there is a comparable solution for XML mappings. Specifying the order of column in an index is what it's there for, don't you think? I mean, the usage example you gave is of the form: "I want columns of these types to go later".