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This is an automated cherry-pick of pingcap#18318
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Signed-off-by: ti-chi-bot <[email protected]>
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63 changes: 63 additions & 0 deletions sql-statements/sql-statement-show-stats-buckets.md
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---
title: SHOW STATS_BUCKETS
summary: TiDB 数据库中 SHOW STATS_BUCKETS 的使用概况。
---

# SHOW STATS_BUCKETS

`SHOW STATS_BUCKETS` 语句显示[常规统计信息](/statistics.md)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``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

```ebnf+diagram
ShowStatsBucketsStmt ::=
"SHOW" "STATS_BUCKETS" ShowLikeOrWhere?
ShowLikeOrWhere ::=
"LIKE" SimpleExpr
| "WHERE" Expression
```

## 示例

```sql
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。

## 另请参阅

* [`ANALYZE`](/sql-statements/sql-statement-analyze-table.md)
* [常规统计信息](/statistics.md)
2 changes: 1 addition & 1 deletion system-variables.md
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Expand Up @@ -966,7 +966,7 @@ MPP 是 TiFlash 引擎提供的分布式计算框架,允许节点之间的数
### `tidb_analyze_distsql_scan_concurrency` <span class="version-mark">从 v7.6.0 版本开始引入</span>
- 作用域:GLOBAL
- 作用域:SESSION | GLOBAL
- 是否持久化到集群:是
- 是否受 Hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value) 控制:否
- 类型:整数型
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