spring - Prevent Hibernate from generating duplicate foreign keys on table?

Question

Our site uses Spring (5.2.8.RELEASE), Hibernate (5.4.19.Final), Tomcat (8.5.x), and SQL Server (2014). Recently, we noticed that the performance is bad in case of deleting a simple record. We found out that it is caused by duplicate foreign keys that were generated by Hibernate. When there is a new table or field, we let Hibernate generate needed new tables or keys (primary key or foreign key) by setting

hibernate.hbm2ddl.auto=update

This is only a one-time deal. After generating new tables or new keys, we prohibit Hibernate from updating any tables or keys by setting

hibernate.hbm2ddl.auto=none

However, hibernate.hbm2ddl.auto=update generates duplicate foreign keys on existing tables. For example, the site allows people to leave comments and upvote/downvote comments. Upvote/downvote table has references to Comment and Account tables, recording which comment was upvoted/downvoted and who did the vote.

Here is the code about the relationship between Vote and Account in Java. In CommentVote.java

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "account")
private Account account;

In Account.java:

@OneToMany(mappedBy = "account", targetEntity = CommentVote.class, 
fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
private List<CommentVote> commentVotes; 

Here is what is shown in SQL Management Studio:

In the above picture, foreign key FK17o46... and FKmgsaf... are duplicates. For example, the foreign keys on the Account field:

If we delete the two duplicate keys and set hibernate.hbm2ddl.auto=update, then the they will be generated again. How can we prevent Hibernate from generating duplicate foreign keys if they already exist on tables while still letting it generating keys only for NEW tables or NEW fields?

question from:https://stackoverflow.com/questions/65871419/prevent-hibernate-from-generating-duplicate-foreign-keys-on-table

Answer 1

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