Sonatype Nexus 3中PostgreSQL数据库错误导致API认证及个人令牌查看失败

新创建的本地用户或获得Nexus访问权限的LDAP用户无法登录仓库，也无法查看个人令牌。nexus.log中记录的错误信息如下：

Error updating database.  Cause: org.postgresql.util.PSQLException: ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification
### The error may exist in org/sonatype/nexus/internal/security/apikey/ApiKeyDAO.xml
### The error may involve org.sonatype.nexus.internal.security.apikey.ApiKeyDAO.save-Inline
### The error occurred while setting parameters
### SQL: INSERT INTO api_key (primary_principal, domain, token, principals , created )         VALUES (?,                 ?, ?, ? , ? )     ON CONFLICT (primary_principal, domain, principals) DO UPDATE SET         token = ?, principals = ?,          created = ? ;
### Cause: org.postgresql.util.PSQLException: ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification'; mapped from: org.sonatype.nexus.datastore.api.DataAccessException:
### Error updating database.  Cause: org.postgresql.util.PSQLException: ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification
### The error may exist in org/sonatype/nexus/internal/security/apikey/ApiKeyDAO.xml
### The error may involve org.sonatype.nexus.internal.security.apikey.ApiKeyDAO.save-Inline
### The error occurred while setting parameters

• 停止Nexus服务，避免操作数据库时产生冲突
• 使用PostgreSQL客户端（如psql）连接到Nexus对应的数据库实例
• 切换至Nexus使用的数据库（替换为实际数据库名）：

  \c nexus_database
  

• 为api_key表添加指定的唯一约束：

  ALTER TABLE api_key ADD CONSTRAINT api_key_unique_constraint UNIQUE (primary_principal, domain, principals);
  

• 启动Nexus服务，测试用户登录及个人令牌查看功能，确认问题解决

内容的提问来源于stack exchange，提问作者Gabriella Turek