作者在一次建表时遇到了 1499 报错，经过排查和计算确定出单机建表的最大分区数。

作者：何文超

爱可生南区交付服务部 DBA 团队成员，主要负责 MySQL 故障处理，MySQL 高可用架构改造，OceanBase 相关技术支持。爱好足球，羽毛球。

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背景

ERROR 1499 (HY000): Too many partitions (including subpartitions) were defined

创建表报错，虽然是内部错误，但是错误信息是指：创建了太多了分区。

[root@observer04 ~]# mysql -h10.186.64.125 -P2883 -uroot@wenchao_mysql#hwc_cluster:1682755171 -p"xxxx"  
MySQL [lss]> CREATE TABLE `wms_order` (
  `A1` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A1',
  `A2` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A2',
  `A3` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A3',
  `A4` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A4',
  `A5` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A5',
  `A6` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A6',
  `A7` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A7',
  `A8` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A8',
  `A9` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A9',
  `A10` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'A10'
) DEFAULT CHARSET = utf8mb4 ROW_FORMAT = DYNAMIC COMPRESSION = 'zstd_1.0' REPLICA_NUM = 3 BLOCK_SIZE = 16384 USE_BLOOM_FILTER = FALSE TABLET_SIZE = 134217728 PCTFREE = 0 COMMENT = '物流订单表'
MySQL [lss]> ERROR 1499 (HY000): Too many partitions (including subpartitions) were defined

接下来我们分析一下问题的原因。

排查

2.1 检查参数

1. 检查每个 OBServer 上可以创建最大的分区数量，当前是 500000。

[root@observer04 ~]# mysql -h10.186.64.125 -P2883 -uroot@sys#hwc_cluster:1682755171 -p"xxxx" -A oceanBase

MySQL [oceanBase]> select * from __all_virtual_sys_parameter_stat where name like '%_max_partition_%';
+-------+----------+---------------+----------+-------------------------------+-----------+--------+--------------+---------------------------------------------+-------------+----------+---------------+---------+---------+-------------------+
| zone  | svr_type | svr_ip        | svr_port | name                          | data_type | value  | value_strict | info                                        | need_reboot | section  | visible_level | scope   | source  | edit_level        |
+-------+----------+---------------+----------+-------------------------------+-----------+--------+--------------+---------------------------------------------+-------------+----------+---------------+---------+---------+-------------------+
| zone1 | observer | 10.186.64.122 |     2882 | _max_partition_cnt_per_server | NULL      | 500000 | NULL         | specify max partition count on one observer |        NULL | OBSERVER | NULL          | CLUSTER | DEFAULT | DYNAMIC_EFFECTIVE |
+-------+----------+---------------+----------+-------------------------------+-----------+--------+--------------+---------------------------------------------+-------------+----------+---------------+---------+---------+-------------------+

2. 检查当前分区数量的和，目前并没有超过这个限制（500000）。

MySQL [oceanBase]> select count(*) from v$partition;
+----------+
| count(*) |
+----------+
|   421485 |
+----------+

2.2 检查回收站

1. 检查回收站是否开启？

[root@observer04 ~]# mysql -h10.186.64.125 -P2883 -uroot@wenchao_mysql#hwc_cluster:1682755171 -p"xxxx"

MySQL [lss]> show variables like '%recy%';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| recyclebin    | ON    |
+---------------+-------+
1 row in set (0.01 sec)

2. 检查回收站中是否存在未删除的分区表？

MySQL [lss]> show recyclebin;
+-----------------------------------------+---------------+-------+----------------------------+
| OBJECT_NAME                             | ORIGINAL_NAME | TYPE  | CREATETIME                 |
+-----------------------------------------+---------------+-------+----------------------------+
| __recycle_$_1682755171_1689139725669688 | mytable_1     | TABLE | 2023-07-12 13:28:45.687379 |
| __recycle_$_1682755171_1689139737584112 | mytable_1     | TABLE | 2023-07-12 13:28:57.584660 |
| __recycle_$_1682755171_1689139750594392 | t1            | TABLE | 2023-07-12 13:29:10.594118 |
+-----------------------------------------+---------------+-------+----------------------------+
3 rows in set (0.01 sec)

如果存在，需要和业务侧沟通是否可以清理。回收站的表清理后，发现分区表数量减少，但是创建表依旧报错。

3. 查看回收站中中对象保留天数。

MySQL [lss]> SHOW PARAMETERS LIKE 'recyclebin_object_expire_time'\G;
*************************** 1. row ***************************
      zone: zone1
  svr_type: observer
    svr_ip: 10.186.64.122
  svr_port: 2882
      name: recyclebin_object_expire_time
 data_type: NULL
     value: 0s
      info: recyclebin object expire time, default 0 that means auto purge recyclebin off. Range: [0s, +∞)
   section: ROOT_SERVICE
     scope: CLUSTER
    source: DEFAULT
edit_level: DYNAMIC_EFFECTIVE
1 row in set (0.02 sec)

配置项 recyclebin_object_expire_time 的取值说明如下：

• 当其值为 0s 时，表示关闭自动 Purge 回收站功能。
• 当其值不为 0s 时，表示回收一段时间前进入回收站的 Schema 对象。

2.3 检查租户内存

1. 找到分区数最多的 10 个租户。

[root@observer04 ~]# mysql -h10.186.64.125 -P2883 -uroot@sys#hwc_cluster:1682755171 -p"xxxx"

// 1. 找到分区数最多的 10 个租户
SELECT t2.tenant_name,t2.tenant_id, t1.replica_count
FROM
 (SELECT tenant_id, COUNT(*) AS replica_count
  FROM __all_virtual_partition_info
  GROUP BY tenant_id
  ORDER BY replica_count DESC
  LIMIT 10) t1
JOIN
 (SELECT tenant_id, tenant_name
  FROM __all_tenant) t2
ON t1.tenant_id=t2.tenant_id
ORDER BY replica_count DESC;
+-------------------+-----------+---------------+
| tenant_name       | tenant_id | replica_count |
+-------------------+-----------+---------------+
| wenchao_mysql     |      1100 |        107853 |
| wenchao_01        |      1088 |         99846 |
| wenchao_02        |      1104 |         15873 |
| wenchao_03        |         1 |          3867 |
| wenchao_04        |      1044 |          3270 |
| wenchao_05        |      1066 |          2811 |
| wenchao_06        |      1079 |          2658 |
| wenchao_07        |      1103 |          2103 |
| wenchao_08        |      1057 |          2040 |
| wenchao_09        |      1016 |          1950 |
+-------------------+-----------+---------------+
10 rows in set (0.13 sec)

2. 查找租户有多少表。

select count(*),svr_Ip from __all_virtual_meta_table where tenant_id=1100 and role=1 group by svr_ip;
+----------+-------------+
| count(*) | svr_Ip      |
+----------+-------------+
|   11921  |10.186.64.103|
|   11868  |10.186.64.104|
|   12013  |10.186.64.105|
+----------+-------------+
3 rows in set (0.35 sec)

3. 计算租户需要扩容内存大小。

• 租户当前分区总数 num=107853/副本数
• 租户可用内存上限=(1-memstore_limit_percentage)*租户 unit 的内存大小 =(1-0.8)*24GB=4.8GB
• 单个副本分区所需总内存 partition_mem=128k*(107853/3)+max(1000,(107853/3)/10)*400k=5.75GB

注意：单个副本分区所需总内存 > 租户可用内存上限,租户所需内存超限,需要对租户内存进行扩容。

4. 根据租户内存计算最大分区数量。

• 单机租户允许创建的最大分区数量(max_memory-memstore_limit)/partition_mem_n
• 单机租户允许创建的最大分区数量(24-24*0.8)/(5.75/(107853/3))=4.8/(5.75/(107853/3))=30011
• partition_mem_n：指的是单个分区所需总内存

临时处理方案：扩容租户内存。

根源治理：不可能无限扩内存；给出业务方合理的分区数量限制，建议业务侧合理使用分区表，制定合理的定期清理策略。

总结

根据上述计算得出：单机租户允许创建的最大分区数量为 30011，建议业务侧注意控制分区数量，以免超限，对业务造成影响。