Android Room编译时警告外键中的列不是索引的一部分。什么意思？

Question

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"CREATE TABLE IF NOT EXISTS `JoinNotesTags` (
    `id` INTEGER PRIMARY KEY AUTOINCREMENT, 
    `noteId` INTEGER, 
    `tagId` INTEGER, 
    FOREIGN KEY(`noteId`) REFERENCES `Note`(`id`) ON UPDATE NO ACTION ON DELETE CASCADE , 
    FOREIGN KEY(`tagId`) REFERENCES `Tag`(`id`) ON UPDATE NO ACTION ON DELETE NO ACTION 
)"

@Entity(
        indices = arrayOf(Index(value = *arrayOf("noteId", "tagId"), unique = true)),
        foreignKeys = arrayOf(
                ForeignKey(
                        entity = Note::class,
                        parentColumns = arrayOf("id"),
                        childColumns = arrayOf("noteId"),
                        onDelete = ForeignKey.CASCADE),
                ForeignKey(
                        entity = Tag::class,
                        parentColumns = arrayOf("id"),
                        childColumns = arrayOf("tagId"))
        )
)

"CREATE UNIQUE INDEX `index_JoinNotesTags_noteId_tagId` 
    ON `JoinNotesTags` (`noteId`, `tagId`)"

那么，我的问题是：这个警告是否只是（仍然是alpha-release）Room库中的一个bug--即编译时分析忽略了tagid是这个复合索引的一部分这一事实？或者我真的有索引问题，我需要解决，以避免全表扫描？

Answer 1

在kotlin代码中：

之前

@ColumnInfo(name = "question_id")
var questionId: Long

之后

@ColumnInfo(name = "question_id", index = true) //just add index = true
var questionId: Long