Use the List-index attribute of the list set in Hibernate search

This article will introduce you to the List-index attributes and problems of using the list set in Hibernate search. I hope this tutorial will be helpful to you.

Hibernate provides the built-in index () function:

The Code is as follows:	Copy code
Select item, index (item) from Order order join Order. items item where index (item) <5

A problem in hibernate using list set ing

Main Problem: list-index in the ing list in hibernate:
See a configuration file:

The Code is as follows:

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<Class name = "User" table = "l_user"> <Id column = "id" name = "id"/> <Property name = "name" column = "username"/> <List name = "userInfoList" inverse = "true" cascade = "all" lazy = "false"> <Key column = "userid" not-null = "true"/> <List-index column = "userinfoid"/> <One-to-learn class = "UserInfo"/> </List> </Class> <Class name = "UserInfo" table = "l_userinfo"> <Id name = "userinfoid" column = "userinfoid"/> <Property name = "infoType" column = "infotype"/> <Property name = "startDate" column = "startdate" type = "timestamp"/> <Property name = "endDate" column = "enddate" type = "timestamp"/> <Role-to-one name = "includeUser" column = "userid" class = "User"/> </Class>

In the configuration file of the User class, a List is configured to specify its association with UserInfo. There is a key, which is the foreign key of the table associated with the User class in the table corresponding to the specified UserInfo class. UserId is used, and List-index is the content to be configured in an ordered set. Here we configure userinfoid as the primary key of the table corresponding to UserInfo. But there is a problem here: list-index plays a very important role when we get the User object and then get the List of UserInfo associated with it. List-index will start from 0 and then auto-increment. If a User has 100 associated UserInfo objects. Assume that the IDs of these UserInfo instances are from 0 to 99. He will get the 100 associated objects. If the UserInfo IDs are from 0-50 100-149, then there will be problems, when we access UserInfoLIst through a User, hibernate will automatically issue an SQL statement to obtain the UserInfo object associated with the User. But he will get a UserInfoLIst with a size of 150, but not every one of this list is a complete UserInfo object. In addition, the redundant UserInfo objects are null in this list. This will lead to a very serious problem. If our UserInfo has an Id of 10000, the List returned by UserInfo is a list with a size of 10000. But there are many empty objects in it. In addition, we will do a lot of useless work when traversing and accessing the objects in it. Therefore, it is necessary to create another attribute as the list-index of List ing. However, it is very necessary for us to maintain his value and ensure that he is continuous. In this case, it is not advisable to maintain a bidirectional one-to-many relationship using a foreign key. Or we can replace it with set directly.