程序包 org.babyfish.jimmer.sql

注释接口 KeyUniqueConstraint

@Documented @Retention(RUNTIME) @Target(TYPE) public @interface KeyUniqueConstraint
This annotation can affect the behavior of the save command.
  • If an entity class is decorated with this annotation, it means that there is a uniqueness constraint in the database that contains the '@Key' fields and logical deleted flag field, and it is possible (but not absolute) that the SQL level ability to to implement upsert operations.
  • Otherwise, it is up to jimmer to determine whether an inserting or updating should be executed through a SQL-query.

  • 可选元素概要

    可选元素
    修饰符和类型
    可选元素
    说明
    boolean
    isNullNotDistinct
    This argument is designed for Postgres.
    boolean
    noMoreUniqueConstraints
    This argument is designed for MySQL.

  • 元素详细资料

    • noMoreUniqueConstraints

      boolean noMoreUniqueConstraints
      This argument is designed for MySQL.

      If you save an object with an ID proeprty, MySQL's `insert... on duplicate...` operation can complete the upsert operation well, and there is no need configure it.

      However, this argument is useful for saving objects that do not have id property.

      For object without id property, MySQL's `insert... on duplicate...` statement indicates whether an insert or update should be executed based on all other unique fields except the primary key. These uniqueness fields may not belong to one same uniqueness constraint, and may belong to different uniqueness constraints. If the latter is the case, jimmer will give up the ability to use the SQL-level upsert.

      In this case, you can configure this parameter to true to tell jimmer that the current entity has only one unique constraint in the database, thus increasing the probability that jimmer will use the upsert capability at the SQL level

      默认值:
      false

    • isNullNotDistinct

      boolean isNullNotDistinct
      This argument is designed for Postgres.

      Postgres' `insert... on conflict(f1, f2, ..., fn) do ...` statement requires conflicting columns 'f1, f2,... fn' must be members of a uniqueness constraint.

      In most databases, null is treated as a special treat, and null is not equal to itself. Even if there is a uniqueness constraint, null fields can lead to duplicate data. Therefore, if some objects contain null `@key` properties, by default, jimmer will also give up the upsert capability of SQL-level and execute an additional SQL query.

      Fortunately, postgres is very powerful, it allows developers to specify how to handle nullable fields of unique constraint. If you have already set the 'NULLS NOT DISTINCT' option for the unique constraint in database, you can configure this argument to true to increase the probability that jimmer will use the upsert capability at the SQL level

      默认值:
      false