为列出表和索引大小简化Postgres SQL查询？

Question

以下Postgres SQL查询将列出所有模式及其大小和索引大小的所有表.如果表只是一个索引表,它将显示为100%索引.

SELECT schema,
       name,
       pg_size_pretty(CASE WHEN is_index THEN 0 ELSE s      END) AS size,
       pg_size_pretty(CASE WHEN is_index THEN s ELSE st - s END) AS index,
       CASE WHEN st = 0   THEN 0
            WHEN is_index THEN 100
                          ELSE 100 - ((s*100) / st) END || '%' as ratio,
       pg_size_pretty(st) as total
  FROM (SELECT *,
               st = s AS is_index
          FROM (SELECT nspname as schema,
                       relname as name,
                       pg_relation_size(nspname || '.' || relname) as s,
                       pg_total_relation_size(nspname || '.' || relname) as st
                  FROM pg_class
          JOIN pg_namespace ON (relnamespace = pg_namespace.oid)) AS p)                                                           
    AS pp                                                                   
 ORDER BY st DESC LIMIT 30;

它将给出以下结果:

 schema         |          name          |  size   |  index  | ratio |  total
----------------+------------------------+---------+---------+-------+---------
 public         | conf                   | 4072 kB | 4360 kB | 52%   | 8432 kB
 archive        | product_param          | 4048 kB | 3968 kB | 50%   | 8016 kB                                                   
 public         | conf_pkey              | 0 bytes | 4320 kB | 100%  | 4320 kB
 archive        | product_value          | 1568 kB | 1136 kB | 43%   | 2704 kB
 public         | param_mapping          | 1472 kB | 832 kB  | 37%   | 2304 kB
 archive        | supplie_price          | 944 kB  | 896 kB  | 49%   | 1840 kB
 public         | product_param_param_id | 0 bytes | 1552 kB | 100%  | 1552 kB
 archive        | product_param_id       | 0 bytes | 1536 kB | 100%  | 1536 kB

我已经到了一个地方,我看不到所有树木的森林,而且它开始变得有点笨拙.

我想知道其中有什么东西可以简化或冗余吗？如果可以使查询更简单,则列不一定保持不变.

Answer 1

我通过以下查询得到了可比较的结果（具有不同的格式）：

select
    nspname as schema,
    relname as name,
    pg_relation_size(pg_class.oid) as size,
    pg_indexes_size(pg_class.oid) as index,
    pg_total_relation_size(pg_class.oid) as total,
    100 * case when relkind = 'i' then pg_relation_size(pg_class.oid) 
                                  else pg_indexes_size(pg_class.oid) end 
        / pg_total_relation_size(pg_class.oid) as i_ratio
from 
    pg_class
    join pg_namespace on relnamespace = pg_namespace.oid
order by 5 desc