SHOW STATS_BUCKETS
SHOW STATS_BUCKETS 语句显示常规统计信息中桶的信息。
目前，SHOW STATS_BUCKETS 语句返回以下列：
| 列名 | 说明 |
|---|---|
Db_name | 数据库名 |
Table_name | 表名 |
Partition_name | 分区名 |
Column_name | 取决于 Is_index 值：Is_index 为 0 时显示列名，为 1 时显示索引名 |
Is_index | 是否是索引列 |
Bucket_id | 桶的 ID |
Count | 该桶和之前桶中所有数值的个数 |
Repeats | 最大值的出现次数 |
Lower_bound | 最小值 |
Upper_bound | 最大值 |
Ndv | 桶中不同值的数量。该字段已废弃，其值由于不准确会始终显示为 0。 |
语法图
- ShowStatsBucketsStmt
- ShowLikeOrWhere
ShowStatsBucketsStmt ::=
"SHOW" "STATS_BUCKETS" ShowLikeOrWhere?
ShowLikeOrWhere ::=
"LIKE" SimpleExpr
| "WHERE" Expression
示例
SHOW STATS_BUCKETS WHERE Table_name='t';
+---------+------------+----------------+-------------+----------+-----------+-------+---------+--------------------------+--------------------------+------+
| Db_name | Table_name | Partition_name | Column_name | Is_index | Bucket_id | Count | Repeats | Lower_Bound | Upper_Bound | Ndv |
+---------+------------+----------------+-------------+----------+-----------+-------+---------+--------------------------+--------------------------+------+
| test | t | | a | 0 | 0 | 1 | 1 | 2023-12-27 00:00:00 | 2023-12-27 00:00:00 | 0 |
| test | t | | a | 0 | 1 | 2 | 1 | 2023-12-28 00:00:00 | 2023-12-28 00:00:00 | 0 |
| test | t | | ia | 1 | 0 | 1 | 1 | (NULL, 2) | (NULL, 2) | 0 |
| test | t | | ia | 1 | 1 | 2 | 1 | (NULL, 4) | (NULL, 4) | 0 |
| test | t | | ia | 1 | 2 | 3 | 1 | (2023-12-27 00:00:00, 1) | (2023-12-27 00:00:00, 1) | 0 |
| test | t | | ia | 1 | 3 | 4 | 1 | (2023-12-28 00:00:00, 3) | (2023-12-28 00:00:00, 3) | 0 |
+---------+------------+----------------+-------------+----------+-----------+-------+---------+--------------------------+--------------------------+------+
6 rows in set (0.00 sec)
MySQL 兼容性
该语句是 TiDB 对 MySQL 语法的扩展。