提示
原文：https://gorm.io/docs/hints.html
GORM provides optimizer/index/comment hints support
GORM提供了优化器/索引/注释提示支持。
原文：https://github.com/go-gorm/hints
优化器提示 Optimizer Hints
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| import "gorm.io/hints"
db.Clauses(hints.New("hint")).Find(&User{})
// SELECT * /*+ hint */ FROM `users`
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索引提示 Index Hints
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| import "gorm.io/hints"
db.Clauses(hints.UseIndex("idx_user_name")).Find(&User{})
// SELECT * FROM `users` USE INDEX (`idx_user_name`)
db.Clauses(hints.ForceIndex("idx_user_name", "idx_user_id").ForJoin()).Find(&User{})
// SELECT * FROM `users` FORCE INDEX FOR JOIN (`idx_user_name`,`idx_user_id`)"
db.Clauses(
hints.ForceIndex("idx_user_name", "idx_user_id").ForOrderBy(),
hints.IgnoreIndex("idx_user_name").ForGroupBy(),
).Find(&User{})
// SELECT * FROM `users` FORCE INDEX FOR ORDER BY (`idx_user_name`,`idx_user_id`) IGNORE INDEX FOR GROUP BY (`idx_user_name`)"
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| import "gorm.io/hints"
db.Clauses(hints.Comment("select", "master")).Find(&User{})
// SELECT /*master*/ * FROM `users`;
db.Clauses(hints.CommentBefore("insert", "node2")).Create(&user)
// /*node2*/ INSERT INTO `users` ...;
db.Clauses(hints.CommentAfter("select", "node2")).Create(&user)
// /*node2*/ INSERT INTO `users` ...;
db.Clauses(hints.CommentAfter("where", "hint")).Find(&User{}, "id = ?", 1)
// SELECT * FROM `users` WHERE id = ? /* hint */
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