如何用SQL语句来查询表或索引的行存/列存存储方式｜OceanBase 用户问题集锦

一、问题背景

自OceanBase 4.3.0版本起，支持了列存引擎，允许表和索引以行存、纯列存或行列冗余的形式创建，且这些存储方式可以自由组合。除了使用 show create table命令来查看表和索引的存储类型外，也有用户询问如何通过SQL语句来查询表或索引的存储方式。那么，具体该如何操作呢？

二、测试表

说明：这里仅列举了部分组合，还有其他的组合应该也是类似的，不再赘述，欢迎测试，拍砖。

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-- 行存表，行存索引
create table  t1(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t1_c2(c2)) partition by hash(c1) partitions 3;
create table  t2(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t2_c2(c2)) partition by hash(c1) partitions 3 with column group(all columns);
create table  t3(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t3_c2(c2) with column group(all columns)) partition by hash(c1) partitions 3 with column group(all columns);

-- 行存表，纯列存索引
create table  t4(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t4_c2(c2) with column group(each column)) partition by hash(c1) partitions 3;

-- 行存表，行列混合索引
create table  t5(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t5_c2(c2) with column group(each column,all columns)) partition by hash(c1) partitions 3;

-- 纯列存表，行存索引
create table  t6(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t6_c2(c2) with column group(all columns)) partition by hash(c1) partitions 3 with column group(each column);
create table  t7(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t7_c2(c2)) partition by hash(c1) partitions 3 with column group(each column);

-- 行列混合表，行列混合索引
create table  t8(c1 int,c2 int,c3 int,c4 int,c5 int,primary key(c1),key idx_t8_c2(c2) with column group(each column,all columns)) partition by hash(c1) partitions 3 with column group(each column,all columns);

三、摸索

从列存相关的语法上可以看出，引入列存后新增加了 with column group （xxx）的关键字，可以尝试搜一下哪些表的列上涉及了 column_group 相关的字段，从下面的结果看目前并没有标准表或者视图提供这样的信息。

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MySQL [oceanbase]> select distinct table_name from __all_virtual_table 
where table_id in (select distinct table_id from __all_virtual_column 
                   where column_name like '%column_group%');
+--------------------------------------------+
| table_name                                 |
+--------------------------------------------+
| __all_table_history                        |
| __all_column_group                         |
| __all_column_group_history                 |
| __all_column_group_mapping                 |
| __all_column_group_mapping_history         |
| __all_virtual_core_all_table               |
| __all_virtual_table                        |
| __all_virtual_table_history                |
| __all_virtual_column_group                 |
| __all_virtual_column_group_mapping         |
| __all_virtual_column_group_history         |
| __all_virtual_column_group_mapping_history |
+--------------------------------------------+
12 rows in set (0.97 sec)

从 __all_virtual_column_group 表的 column_group_type 字段，凭感觉可以标识。

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MySQL [oceanbase]> desc __all_virtual_column_group;
+-------------------+--------------+------+-----+---------+-------+
| Field             | Type         | Null | Key | Default | Extra |
+-------------------+--------------+------+-----+---------+-------+
| tenant_id         | bigint(20)   | NO   | PRI | NULL    |       |
| table_id          | bigint(20)   | NO   | PRI | NULL    |       |
| column_group_id   | bigint(20)   | NO   | PRI | NULL    |       |
| gmt_create        | timestamp(6) | NO   |     | NULL    |       |
| gmt_modified      | timestamp(6) | NO   |     | NULL    |       |
| column_group_name | varchar(389) | NO   |     |         |       |
| column_group_type | bigint(20)   | NO   |     | NULL    |       |
| block_size        | bigint(20)   | NO   |     | NULL    |       |
| compressor_type   | bigint(20)   | NO   |     | NULL    |       |
| row_store_type    | bigint(20)   | NO   |     | NULL    |       |
+-------------------+--------------+------+-----+---------+-------+
10 rows in set (0.02 sec)

从代码 src/share/schema/ob_schema_struct.h 找到 column_group 类型的枚举值。

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enum ObColumnGroupType : uint8_t
{
  DEFAULT_COLUMN_GROUP = 0,
  ALL_COLUMN_GROUP,
  ROWKEY_COLUMN_GROUP,
  SINGLE_COLUMN_GROUP,
  NORMAL_COLUMN_GROUP,
  MAX_COLUMN_GROUP
};

四、结论

经过测试发现如何标识表或者索引是行存/纯列存/行列冗余的方式存储，这里之所以给 "结论"使用引号扩起来，原因：

1、受限于自己测试的 case 可能不完善，存在错误的情况，欢迎一起测试，交流。

2、随着版本的迭代，针对枚举值可能会有调整/比如增删等，应以实际版本中的枚举值为准。

某个租户下当同一个 table_id 的 column_group_type 包含3 但是不包含1，输出：纯列存表
某个租户下当同一个 table_id 的 column_group_type 包含1 和 3，输出：行列混合表
其他情况均输出：纯行存表

五、查询sql和结果

说明：可以按需调整 tenant_name/database_name

sql_1(混合查询）

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select 
    t1.tenant_name,
    t2.database_name,
    case 
        when t2.table_type = 'user table' then t2.table_name
        when t2.table_type = 'index' then t2.index_name
    end as table_name,
    t2.table_id,
    t2.data_table_id,
    t2.table_type,
    case
        when t2.table_type = 'user table' then
            case
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0 then '纯列存表'
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) > 0 then '行列混合表'
                else '纯行存表'
            end
        when t2.table_type = 'index' then
            case
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0 then '纯列存索引'
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) > 0 then '行列混合索引'
                else '纯行存索引'
            end
    end as storage_type,
    coalesce(t3.table_name, null) as main_table_name
from 
    __all_virtual_column_group cg
join 
    dba_ob_tenants t1 on cg.tenant_id = t1.tenant_id
join 
    cdb_ob_table_locations t2 on cg.tenant_id = t2.tenant_id and cg.table_id = t2.table_id
left join 
    cdb_ob_table_locations t3 on t2.data_table_id = t3.table_id
where 
    t1.tenant_name in ('test1','test7')
    and t2.database_name in ('row_column_db','db100','db600')
    and t2.table_type in ('user table', 'index')
group by 
    t1.tenant_name, t2.database_name, t2.table_name, t2.table_id, t2.data_table_id, t2.table_type, main_table_name
order by t1.tenant_name,t2.database_name, t2.table_name;

sql1_查询结果

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+-------------+---------------+------------+----------+---------------+------------+--------------------+-----------------+
| tenant_name | database_name | table_name | table_id | data_table_id | table_type | storage_type       | main_table_name |
+-------------+---------------+------------+----------+---------------+------------+--------------------+-----------------+
| test1       | row_column_db | t1         |   596454 |          NULL | USER TABLE | 纯行存表           | NULL            |
| test1       | row_column_db | t2         |   596462 |          NULL | USER TABLE | 纯行存表           | NULL            |
| test1       | row_column_db | t3         |   596470 |          NULL | USER TABLE | 纯行存表           | NULL            |
| test1       | row_column_db | t4         |   596478 |          NULL | USER TABLE | 纯行存表           | NULL            |
| test1       | row_column_db | idx_t1_c2  |   596455 |        596454 | INDEX      | 纯行存索引         | t1              |
| test1       | row_column_db | idx_t2_c2  |   596463 |        596462 | INDEX      | 纯行存索引         | t2              |
| test1       | row_column_db | idx_t3_c2  |   596471 |        596470 | INDEX      | 纯行存索引         | t3              |
| test1       | row_column_db | idx_t4_c2  |   596479 |        596478 | INDEX      | 纯列存索引         | t4              |
| test7       | db100         | t8         |   500070 |          NULL | USER TABLE | 行列混合表         | NULL            |
| test7       | db100         | idx_t8_c2  |   500071 |        500070 | INDEX      | 行列混合索引       | t8              |
| test7       | db600         | t5         |   500045 |          NULL | USER TABLE | 纯行存表           | NULL            |
| test7       | db600         | t6         |   500053 |          NULL | USER TABLE | 纯列存表           | NULL            |
| test7       | db600         | t7         |   500061 |          NULL | USER TABLE | 纯列存表           | NULL            |
| test7       | db600         | idx_t5_c2  |   500046 |        500045 | INDEX      | 行列混合索引       | t5              |
| test7       | db600         | idx_t6_c2  |   500054 |        500053 | INDEX      | 纯行存索引         | t6              |
| test7       | db600         | idx_t7_c2  |   500062 |        500061 | INDEX      | 纯行存索引         | t7              |
+-------------+---------------+------------+----------+---------------+------------+--------------------+-----------------+
16 rows in set (3.45 sec)

sql2_查询纯列存的表/索引

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select 
    t1.tenant_name,
    t2.database_name,
    case 
        when t2.table_type = 'user table' then t2.table_name
        when t2.table_type = 'index' then t2.index_name
    end as table_name,
    t2.table_id,
    t2.data_table_id,
    t2.table_type,
    case
        when t2.table_type = 'user table' then
            case
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0 then '纯列存表'
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) > 0 then '行列混合表'
                else '纯行存表'
            end
        when t2.table_type = 'index' then
            case
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0 then '纯列存索引'
                when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                     and sum(case when cg.column_group_type = 1 then 1 else 0 end) > 0 then '行列混合索引'
                else '纯行存索引'
            end
    end as storage_type,
    coalesce(t3.table_name, null) as main_table_name
from 
    __all_virtual_column_group cg
join 
    dba_ob_tenants t1 on cg.tenant_id = t1.tenant_id
join 
    cdb_ob_table_locations t2 on cg.tenant_id = t2.tenant_id and cg.table_id = t2.table_id
left join 
    cdb_ob_table_locations t3 on t2.data_table_id = t3.table_id
where 
    t1.tenant_name in ('test1','test7')
    and t2.database_name in ('row_column_db','db100','db600')
    and t2.table_type in ('user table', 'index')
group by 
    t1.tenant_name, t2.database_name, t2.table_name, t2.table_id, t2.data_table_id, t2.table_type, main_table_name
having
    (t2.table_type = 'user table' and sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0)
    or
    (t2.table_type = 'index' and sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0)
order by 
    t1.tenant_name, t2.database_name, t2.table_name;

sql2_查询结果

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+-------------+---------------+------------+----------+---------------+------------+-----------------+-----------------+
| tenant_name | database_name | table_name | table_id | data_table_id | table_type | storage_type    | main_table_name |
+-------------+---------------+------------+----------+---------------+------------+-----------------+-----------------+
| test1       | row_column_db | idx_t4_c2  |   596479 |        596478 | INDEX      | 纯列存索引      | t4              |
| test7       | db600         | t6         |   500053 |          NULL | USER TABLE | 纯列存表        | NULL            |
| test7       | db600         | t7         |   500061 |          NULL | USER TABLE | 纯列存表        | NULL            |
+-------------+---------------+------------+----------+---------------+------------+-----------------+-----------------+
3 rows in set (3.48 sec)

sql3_查询行列冗余的表/索引

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SELECT 
    tenant_name,
    database_name,
    table_name,
    table_id,
    data_table_id,
    table_type,
    storage_type,
    main_table_name
FROM (
    select 
        t1.tenant_name,
        t2.database_name,
        case 
            when t2.table_type = 'user table' then t2.table_name
            when t2.table_type = 'index' then t2.index_name
        end as table_name,
        t2.table_id,
        t2.data_table_id,
        t2.table_type,
        case
            when t2.table_type = 'user table' then
                case
                    when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                         and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0 then '纯列存表'
                    when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                         and sum(case when cg.column_group_type = 1 then 1 else 0 end) > 0 then '行列混合表'
                    else '纯行存表'
                end
            when t2.table_type = 'index' then
                case
                    when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                         and sum(case when cg.column_group_type = 1 then 1 else 0 end) = 0 then '纯列存索引'
                    when sum(case when cg.column_group_type = 3 then 1 else 0 end) > 0 
                         and sum(case when cg.column_group_type = 1 then 1 else 0 end) > 0 then '行列混合索引'
                    else '纯行存索引'
                end
        end as storage_type,
        coalesce(t3.table_name, null) as main_table_name
    from 
        __all_virtual_column_group cg
    join 
        dba_ob_tenants t1 on cg.tenant_id = t1.tenant_id
    join 
        cdb_ob_table_locations t2 on cg.tenant_id = t2.tenant_id and cg.table_id = t2.table_id
    left join 
        cdb_ob_table_locations t3 on t2.data_table_id = t3.table_id
    where 
        t1.tenant_name in ('test1','test7')
        and t2.database_name in ('row_column_db','db100','db600')
        and t2.table_type in ('user table', 'index')
    group by 
        t1.tenant_name, t2.database_name, t2.table_name, t2.table_id, t2.data_table_id, t2.table_type, main_table_name
) subquery
WHERE 
    storage_type IN ('行列混合表', '行列混合索引')
ORDER BY tenant_name, database_name, table_name;

sql3_查询结果

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+-------------+---------------+------------+----------+---------------+------------+--------------------+-----------------+
| tenant_name | database_name | table_name | table_id | data_table_id | table_type | storage_type       | main_table_name |
+-------------+---------------+------------+----------+---------------+------------+--------------------+-----------------+
| test7       | db100         | idx_t8_c2  |   500071 |        500070 | INDEX      | 行列混合索引       | t8              |
| test7       | db100         | t8         |   500070 |          NULL | USER TABLE | 行列混合表         | NULL            |
| test7       | db600         | idx_t5_c2  |   500046 |        500045 | INDEX      | 行列混合索引       | t5              |
+-------------+---------------+------------+----------+---------------+------------+--------------------+-----------------+
3 rows in set (3.33 sec)